Linus Torvalds [Thu, 1 Feb 2018 18:00:28 +0000 (10:00 -0800)]
Merge tag 'driver-core-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core
Pull driver core updates from Greg KH:
"Here is the set of "big" driver core patches for 4.16-rc1.
The majority of the work here is in the firmware subsystem, with
reworks to try to attempt to make the code easier to handle in the
long run, but no functional change. There's also some tree-wide sysfs
attribute fixups with lots of acks from the various subsystem
maintainers, as well as a handful of other normal fixes and changes.
And finally, some license cleanups for the driver core and sysfs code.
All have been in linux-next for a while with no reported issues"
* tag 'driver-core-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (48 commits)
device property: Define type of PROPERTY_ENRTY_*() macros
device property: Reuse property_entry_free_data()
device property: Move property_entry_free_data() upper
firmware: Fix up docs referring to FIRMWARE_IN_KERNEL
firmware: Drop FIRMWARE_IN_KERNEL Kconfig option
USB: serial: keyspan: Drop firmware Kconfig options
sysfs: remove DEBUG defines
sysfs: use SPDX identifiers
drivers: base: add coredump driver ops
sysfs: add attribute specification for /sysfs/devices/.../coredump
test_firmware: fix missing unlock on error in config_num_requests_store()
test_firmware: make local symbol test_fw_config static
sysfs: turn WARN() into pr_warn()
firmware: Fix a typo in fallback-mechanisms.rst
treewide: Use DEVICE_ATTR_WO
treewide: Use DEVICE_ATTR_RO
treewide: Use DEVICE_ATTR_RW
sysfs.h: Use octal permissions
component: add debugfs support
bus: simple-pm-bus: convert bool SIMPLE_PM_BUS to tristate
...
Linus Torvalds [Thu, 1 Feb 2018 17:51:57 +0000 (09:51 -0800)]
Merge tag 'staging-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging
Pull staging/IIO updates from Greg KH:
"Here is the big Staging and IIO driver patches for 4.16-rc1.
There is the normal amount of new IIO drivers added, like all
releases.
The networking IPX and the ncpfs filesystem are moved into the staging
tree, as they are on their way out of the kernel due to lack of use
anymore.
The visorbus subsystem finall has started moving out of the staging
tree to the "real" part of the kernel, and the most and fsl-mc
codebases are almost ready to move out, that will probably happen for
4.17-rc1 if all goes well.
Other than that, there is a bunch of license header cleanups in the
tree, along with the normal amount of coding style churn that we all
know and love for this codebase. I also got frustrated at the
Meltdown/Spectre mess and took it out on the dgnc tty driver, deleting
huge chunks of it that were never even being used.
Full details of everything is in the shortlog.
All of these patches have been in linux-next for a while with no
reported issues"
* tag 'staging-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging: (627 commits)
staging: rtlwifi: remove redundant initialization of 'cfg_cmd'
staging: rtl8723bs: remove a couple of redundant initializations
staging: comedi: reformat lines to 80 chars or less
staging: lustre: separate a connection destroy from free struct kib_conn
Staging: rtl8723bs: Use !x instead of NULL comparison
Staging: rtl8723bs: Remove dead code
Staging: rtl8723bs: Change names to conform to the kernel code
staging: ccree: Fix missing blank line after declaration
staging: rtl8188eu: remove redundant initialization of 'pwrcfgcmd'
staging: rtlwifi: remove unused RTLHALMAC_ST and RTLPHYDM_ST
staging: fbtft: remove unused FB_TFT_SSD1325 kconfig
staging: comedi: dt2811: remove redundant initialization of 'ns'
staging: wilc1000: fix alignments to match open parenthesis
staging: wilc1000: removed unnecessary defined enums typedef
staging: wilc1000: remove unnecessary use of parentheses
staging: rtl8192u: remove redundant initialization of 'timeout'
staging: sm750fb: fix CamelCase for dispSet var
staging: lustre: lnet/selftest: fix compile error on UP build
staging: rtl8723bs: hal_com_phycfg: Remove unneeded semicolons
staging: rts5208: Fix "seg_no" calculation in reset_ms_card()
...
Linus Torvalds [Thu, 1 Feb 2018 17:46:00 +0000 (09:46 -0800)]
Merge tag 'tty-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty
Pull tty/staging driver updates from Greg KH:
"Here is the big tty/serial driver update for 4.16-rc1.
The usual number of various serial driver fixes and updates to try to
get them to work with crazy hardware configurations (seriously, how
many different ways are hardware engineers going to come up with to
hook up a simple UART?)
There is also some serdev bugfixes and updates, as well as a
smattering of other small fixes in here.
All have been in the linux-next tree for a while, with no reported
issues"
* tag 'tty-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty: (65 commits)
tty: serial: exar: Relocate sleep wake-up handling
tty: fix data race between tty_init_dev and flush of buf
serial: imx: fix endless loop during suspend
serial: core: mark port as initialized after successful IRQ change
serdev: only match serdev devices
serdev: do not generate modaliases for controllers
serial: mxs-auart: don't use GPIOF_* with gpiod_get_direction
serial: 8250_dw: Revert "Improve clock rate setting"
MAINTAINERS: Add myself as designated reviewer for 8250_dw
gpio: serial: max310x: Support open-drain configuration for GPIOs
serdev: Fix serdev_uevent failure on ACPI enumerated serdev-controllers
serial: 8250_ingenic: Parse earlycon options
serial: 8250_ingenic: Add support for the JZ4770 SoC
serial: core: Make uart_parse_options take const char* argument
serial: 8250_of: fix return code when probe function fails to get reset
serial: imx: Only wakeup via RTSDEN bit if the system has RTS/CTS
serial: 8250_uniphier: fix error return code in uniphier_uart_probe()
tty: n_gsm: Allow ADM response in addition to UA for control dlci
tty: omap-serial: Fix initial on-boot RTS GPIO level
tty: serial: jsm: Add one check against NULL pointer dereference
...
Linus Torvalds [Thu, 1 Feb 2018 17:40:49 +0000 (09:40 -0800)]
Merge tag 'usb-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb
Pull USB/PHY updates from Greg KH:
"Here is the big USB and PHY driver update for 4.16-rc1.
Along with the normally expected XHCI, MUSB, and Gadget driver
patches, there are some PHY driver fixes, license cleanups, sysfs
attribute cleanups, usbip changes, and a raft of other smaller fixes
and additions.
Full details are in the shortlog.
All of these have been in the linux-next tree for a long time with no
reported issues"
* tag 'usb-4.16-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/usb: (137 commits)
USB: serial: pl2303: new device id for Chilitag
USB: misc: fix up some remaining DEVICE_ATTR() usages
USB: musb: fix up one odd DEVICE_ATTR() usage
USB: atm: fix up some remaining DEVICE_ATTR() usage
USB: move many drivers to use DEVICE_ATTR_WO
USB: move many drivers to use DEVICE_ATTR_RO
USB: move many drivers to use DEVICE_ATTR_RW
USB: misc: chaoskey: Use true and false for boolean values
USB: storage: remove old wording about how to submit a change
USB: storage: remove invalid URL from drivers
usb: ehci-omap: don't complain on -EPROBE_DEFER when no PHY found
usbip: list: don't list devices attached to vhci_hcd
usbip: prevent bind loops on devices attached to vhci_hcd
USB: serial: remove redundant initializations of 'mos_parport'
usb/gadget: Fix "high bandwidth" check in usb_gadget_ep_match_desc()
usb: gadget: compress return logic into one line
usbip: vhci_hcd: update 'status' file header and format
USB: serial: simple: add Motorola Tetra driver
CDC-ACM: apply quirk for card reader
usb: option: Add support for FS040U modem
...
Pull sparc updates from David Miller:
"Of note is the addition of a driver for the Data Analytics
Accelerator, and some small cleanups"
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-next:
oradax: Fix return value check in dax_attach()
sparc: vDSO: remove an extra tab
sparc64: drop unneeded compat include
sparc64: Oracle DAX driver
sparc64: Oracle DAX infrastructure
Linus Torvalds [Thu, 1 Feb 2018 17:31:04 +0000 (09:31 -0800)]
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux
Pull s390 updates from Martin Schwidefsky:
"Bug fixes, small improvements and one notable change: the system call
table and the unistd.h header are now generated automatically with a
shell script from a text file"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390/decompressor: discard __ksymtab and .eh_frame sections
s390: fix handling of -1 in set{,fs}[gu]id16 syscalls
s390/tools: generate header files in arch/s390/include/generated/
s390/syscalls: use generated syscall_table.h and unistd.h header files
s390/syscalls: add Makefile to generate system call header files
s390/syscalls: add syscalltbl script
s390/syscalls: add system call table
s390/decompressor: swap .text and .rodata.compressed sections
s390/sclp: fix .data section specification
s390/ipl: avoid usage of __section(.data)
s390/head: replace hard coded values with constants
s390/disassembler: add generated gen_opcode_table tool to .gitignore
s390: remove bogus system call table entries
s390/kprobes: remove duplicate includes
s390/dasd: Remove dead return code checks
s390/dasd: Simplify code
s390/vdso: revise CFI annotations of vDSO functions
s390/kernel: emit CFI data in .debug_frame and discard .eh_frame sections
Linus Torvalds [Thu, 1 Feb 2018 03:25:25 +0000 (19:25 -0800)]
Merge tag 'docs-4.16' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"Documentation updates for 4.16.
New stuff includes refcount_t documentation, errseq documentation,
kernel-doc support for nested structure definitions, the removal of
lots of crufty kernel-doc support for unused formats, SPDX tag
documentation, the beginnings of a manual for subsystem maintainers,
and lots of fixes and updates.
As usual, some of the changesets reach outside of Documentation/ to
effect kerneldoc comment fixes. It also adds the new LICENSES
directory, of which Thomas promises I do not need to be the
maintainer"
* tag 'docs-4.16' of git://git.lwn.net/linux: (65 commits)
linux-next: docs-rst: Fix typos in kfigure.py
linux-next: DOC: HWPOISON: Fix path to debugfs in hwpoison.txt
Documentation: Fix misconversion of #if
docs: add index entry for networking/msg_zerocopy
Documentation: security/credentials.rst: explain need to sort group_list
LICENSES: Add MPL-1.1 license
LICENSES: Add the GPL 1.0 license
LICENSES: Add Linux syscall note exception
LICENSES: Add the MIT license
LICENSES: Add the BSD-3-clause "Clear" license
LICENSES: Add the BSD 3-clause "New" or "Revised" License
LICENSES: Add the BSD 2-clause "Simplified" license
LICENSES: Add the LGPL-2.1 license
LICENSES: Add the LGPL 2.0 license
LICENSES: Add the GPL 2.0 license
Documentation: Add license-rules.rst to describe how to properly identify file licenses
scripts: kernel_doc: better handle show warnings logic
fs/*/Kconfig: drop links to 404-compliant http://acl.bestbits.at
doc: md: Fix a file name to md-fault.c in fault-injection.txt
errseq: Add to documentation tree
...
Linus Torvalds [Thu, 1 Feb 2018 03:21:14 +0000 (19:21 -0800)]
Merge branch 'work.vmci' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vmci iov_iter updates from Al Viro:
"Get rid of "is it an iovec or an entire array?" flags in vmxi - just
use iov_iter. Simplifies the living hell out of that code..."
* 'work.vmci' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
vmci: the same on the send side...
vmci: simplify qp_dequeue_locked()
vmci: get rid of qp_memcpy_from_queue()
vmci: fix buf_size in case of iovec-based accesses
Linus Torvalds [Thu, 1 Feb 2018 03:18:12 +0000 (19:18 -0800)]
Merge branch 'work.whack-a-mole' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull asm/uaccess.h whack-a-mole from Al Viro:
"It's linux/uaccess.h, damnit... Oh, well - eventually they'll stop
cropping up..."
* 'work.whack-a-mole' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
asm-prototypes.h: use linux/uaccess.h, not asm/uaccess.h
riscv: use linux/uaccess.h, not asm/uaccess.h...
ppc: for put_user() pull linux/uaccess.h, not asm/uaccess.h
Linus Torvalds [Thu, 1 Feb 2018 02:46:22 +0000 (18:46 -0800)]
Merge branch 'akpm' (patches from Andrew)
Merge updates from Andrew Morton:
- misc fixes
- ocfs2 updates
- most of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (118 commits)
mm: remove PG_highmem description
tools, vm: new option to specify kpageflags file
mm/swap.c: make functions and their kernel-doc agree
mm, memory_hotplug: fix memmap initialization
mm: correct comments regarding do_fault_around()
mm: numa: do not trap faults on shared data section pages.
hugetlb, mbind: fall back to default policy if vma is NULL
hugetlb, mempolicy: fix the mbind hugetlb migration
mm, hugetlb: further simplify hugetlb allocation API
mm, hugetlb: get rid of surplus page accounting tricks
mm, hugetlb: do not rely on overcommit limit during migration
mm, hugetlb: integrate giga hugetlb more naturally to the allocation path
mm, hugetlb: unify core page allocation accounting and initialization
mm/memcontrol.c: try harder to decrease [memory,memsw].limit_in_bytes
mm/memcontrol.c: make local symbol static
mm/hmm: fix uninitialized use of 'entry' in hmm_vma_walk_pmd()
include/linux/mmzone.h: fix explanation of lower bits in the SPARSEMEM mem_map pointer
mm/compaction.c: fix comment for try_to_compact_pages()
mm/page_ext.c: make page_ext_init a noop when CONFIG_PAGE_EXTENSION but nothing uses it
zsmalloc: use U suffix for negative literals being shifted
...
David Rientjes [Thu, 1 Feb 2018 00:21:23 +0000 (16:21 -0800)]
tools, vm: new option to specify kpageflags file
page-types currently hardcodes /proc/kpageflags as the file to parse.
This works when using the tool to examine the state of pageflags on the
same system, but does not allow storing a snapshot of pageflags at a
given time to debug issues nor on a different system.
This allows the user to specify a saved version of kpageflags with a new
page-types -F option.
Randy Dunlap [Thu, 1 Feb 2018 00:21:19 +0000 (16:21 -0800)]
mm/swap.c: make functions and their kernel-doc agree
Fix some basic kernel-doc notation in mm/swap.c:
- for function lru_cache_add_anon(), make its kernel-doc function name
match its function name and change colon to hyphen following the
function name
- for function pagevec_lookup_entries(), change the function parameter
name from nr_pages to nr_entries since that is more descriptive of
what the parameter actually is and then it matches the kernel-doc
comments also
Fix function kernel-doc to match the change in commit 67fd707f4681:
- drop the kernel-doc notation for @nr_pages from
pagevec_lookup_range() and correct the function description for that
change
Link: http://lkml.kernel.org/r/3b42ee3e-04a9-a6ca-6be4-f00752a114fe@infradead.org Fixes: 67fd707f4681 ("mm: remove nr_pages argument from pagevec_lookup_{,range}_tag()") Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Jan Kara <jack@suse.cz> Cc: Matthew Wilcox <willy@infradead.org> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:21:14 +0000 (16:21 -0800)]
mm, memory_hotplug: fix memmap initialization
Bharata has noticed that onlining a newly added memory doesn't increase
the total memory, pointing to commit f7f99100d8d9 ("mm: stop zeroing
memory during allocation in vmemmap") as a culprit. This commit has
changed the way how the memory for memmaps is initialized and moves it
from the allocation time to the initialization time. This works
properly for the early memmap init path.
It doesn't work for the memory hotplug though because we need to mark
page as reserved when the sparsemem section is created and later
initialize it completely during onlining. memmap_init_zone is called in
the early stage of onlining. With the current code it calls
__init_single_page and as such it clears up the whole stage and
therefore online_pages_range skips those pages.
Fix this by skipping mm_zero_struct_page in __init_single_page for
memory hotplug path. This is quite uggly but unifying both early init
and memory hotplug init paths is a large project. Make sure we plug the
regression at least.
Link: http://lkml.kernel.org/r/20180130101141.GW21609@dhcp22.suse.cz Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Tested-by: Bharata B Rao <bharata@linux.vnet.ibm.com> Reviewed-by: Pavel Tatashin <pasha.tatashin@oracle.com> Cc: Steven Sistare <steven.sistare@oracle.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Bob Picco <bob.picco@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are multiple comments surrounding do_fault_around that memtion
fault_around_pages() and fault_around_mask(), two routines that do not
exist. These comments should be reworded to reference
fault_around_bytes, the value which is used to determine how much
do_fault_around() will attempt to read when processing a fault.
These comments should have been updated when fault_around_pages() and
fault_around_mask() were removed in commit aecd6f44266c ("mm: close race
between do_fault_around() and fault_around_bytes_set()").
Fixes: aecd6f44266c1 ("mm: close race between do_fault_around() and fault_around_bytes_set()") Link: http://lkml.kernel.org/r/302D0B14-C7E9-44C6-8BED-033F9ACBD030@oracle.com Signed-off-by: William Kucharski <william.kucharski@oracle.com> Reviewed-by: Larry Bassel <larry.bassel@oracle.com> Cc: Michal Hocko <mhocko@suse.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Henry Willard [Thu, 1 Feb 2018 00:21:07 +0000 (16:21 -0800)]
mm: numa: do not trap faults on shared data section pages.
Workloads consisting of a large number of processes running the same
program with a very large shared data segment may experience performance
problems when numa balancing attempts to migrate the shared cow pages.
This manifests itself with many processes or tasks in
TASK_UNINTERRUPTIBLE state waiting for the shared pages to be migrated.
The program listed below simulates the conditions with these results
when run with 288 processes on a 144 core/8 socket machine.
Average throughput Average throughput Average throughput
with numa_balancing=0 with numa_balancing=1 with numa_balancing=1
without the patch with the patch
--------------------- --------------------- --------------------- 211878220215342107979
Complex production environments show less variability and fewer poorly
performing outliers accompanied with a smaller number of processes
waiting on NUMA page migration with this patch applied. In some cases,
%iowait drops from 16%-26% to 0.
// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2017 Oracle and/or its affiliates. All rights reserved.
*/
#include <sys/time.h>
#include <stdio.h>
#include <wait.h>
#include <sys/mman.h>
This patch changes change_pte_range() to skip shared copy-on-write pages
when called from change_prot_numa().
NOTE: change_prot_numa() is nominally called from task_numa_work() and
queue_pages_test_walk(). task_numa_work() is the auto NUMA balancing
path, and queue_pages_test_walk() is part of explicit NUMA policy
management. However, queue_pages_test_walk() only calls
change_prot_numa() when MPOL_MF_LAZY is specified and currently that is
not allowed, so change_prot_numa() is only called from auto NUMA
balancing.
In the case of explicit NUMA policy management, shared pages are not
migrated unless MPOL_MF_MOVE_ALL is specified, and MPOL_MF_MOVE_ALL
depends on CAP_SYS_NICE. Currently, there is no way to pass information
about MPOL_MF_MOVE_ALL to change_pte_range. This will have to be fixed
if MPOL_MF_LAZY is enabled and MPOL_MF_MOVE_ALL is to be honored in lazy
migration mode.
task_numa_work() skips the read-only VMAs of programs and shared
libraries.
Link: http://lkml.kernel.org/r/1516751617-7369-1-git-send-email-henry.willard@oracle.com Signed-off-by: Henry Willard <henry.willard@oracle.com> Reviewed-by: Håkon Bugge <haakon.bugge@oracle.com> Reviewed-by: Steve Sistare <steven.sistare@oracle.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: "Jérôme Glisse" <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:21:03 +0000 (16:21 -0800)]
hugetlb, mbind: fall back to default policy if vma is NULL
Dan Carpenter has noticed that mbind migration callback (new_page) can
get a NULL vma pointer and choke on it inside alloc_huge_page_vma which
relies on the VMA to get the hstate. We used to BUG_ON this case but
the BUG_+ON has been removed recently by "hugetlb, mempolicy: fix the
mbind hugetlb migration".
The proper way to handle this is to get the hstate from the migrated
page and rely on huge_node (resp. get_vma_policy) do the right thing
with null VMA. We are currently falling back to the default mempolicy
in that case which is in line what THP path is doing here.
Link: http://lkml.kernel.org/r/20180110104712.GR1732@dhcp22.suse.cz Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:21:00 +0000 (16:21 -0800)]
hugetlb, mempolicy: fix the mbind hugetlb migration
do_mbind migration code relies on alloc_huge_page_noerr for hugetlb
pages. alloc_huge_page_noerr uses alloc_huge_page which is a highlevel
allocation function which has to take care of reserves, overcommit or
hugetlb cgroup accounting. None of that is really required for the page
migration because the new page is only temporal and either will replace
the original page or it will be dropped. This is essentially as for
other migration call paths and there shouldn't be any reason to handle
mbind in a special way.
The current implementation is even suboptimal because the migration
might fail just because the hugetlb cgroup limit is reached, or the
overcommit is saturated.
Fix this by making mbind like other hugetlb migration paths. Add a new
migration helper alloc_huge_page_vma as a wrapper around
alloc_huge_page_nodemask with additional mempolicy handling.
alloc_huge_page_noerr has no more users and it can go.
Link: http://lkml.kernel.org/r/20180103093213.26329-7-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:20:56 +0000 (16:20 -0800)]
mm, hugetlb: further simplify hugetlb allocation API
Hugetlb allocator has several layer of allocation functions depending
and the purpose of the allocation. There are two allocators depending
on whether the page can be allocated from the page allocator or we need
a contiguous allocator. This is currently opencoded in
alloc_fresh_huge_page which is the only path that might allocate giga
pages which require the later allocator. Create alloc_fresh_huge_page
which hides this implementation detail and use it in all callers which
hardcoded the buddy allocator path (__hugetlb_alloc_buddy_huge_page).
This shouldn't introduce any funtional change because both migration and
surplus allocators exlude giga pages explicitly.
While we are at it let's do some renaming. The current scheme is not
consistent and overly painfull to read and understand. Get rid of
prefix underscores from most functions. There is no real reason to make
names longer.
* alloc_fresh_huge_page is the new layer to abstract underlying
allocator
* __hugetlb_alloc_buddy_huge_page becomes shorter and neater
alloc_buddy_huge_page.
* Former alloc_fresh_huge_page becomes alloc_pool_huge_page because we put
the new page directly to the pool
* alloc_surplus_huge_page can drop the opencoded prep_new_huge_page code
as it uses alloc_fresh_huge_page now
* others lose their excessive prefix underscores to make names shorter
[dan.carpenter@oracle.com: fix double unlock bug in alloc_surplus_huge_page()] Link: http://lkml.kernel.org/r/20180109200559.g3iz5kvbdrz7yydp@mwanda Link: http://lkml.kernel.org/r/20180103093213.26329-6-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:20:52 +0000 (16:20 -0800)]
mm, hugetlb: get rid of surplus page accounting tricks
alloc_surplus_huge_page increases the pool size and the number of
surplus pages opportunistically to prevent from races with the pool size
change. See commit d1c3fb1f8f29 ("hugetlb: introduce
nr_overcommit_hugepages sysctl") for more details.
The resulting code is unnecessarily hairy, cause code duplication and
doesn't allow to share the allocation paths. Moreover pool size changes
tend to be very seldom so optimizing for them is not really reasonable.
Simplify the code and allow to allocate a fresh surplus page as long as
we are under the overcommit limit and then recheck the condition after
the allocation and drop the new page if the situation has changed. This
should provide a reasonable guarantee that an abrupt allocation requests
will not go way off the limit.
If we consider races with the pool shrinking and enlarging then we
should be reasonably safe as well. In the first case we are off by one
in the worst case and the second case should work OK because the page is
not yet visible. We can waste CPU cycles for the allocation but that
should be acceptable for a relatively rare condition.
Link: http://lkml.kernel.org/r/20180103093213.26329-5-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:20:48 +0000 (16:20 -0800)]
mm, hugetlb: do not rely on overcommit limit during migration
hugepage migration relies on __alloc_buddy_huge_page to get a new page.
This has 2 main disadvantages.
1) it doesn't allow to migrate any huge page if the pool is used
completely which is not an exceptional case as the pool is static and
unused memory is just wasted.
2) it leads to a weird semantic when migration between two numa nodes
might increase the pool size of the destination NUMA node while the
page is in use. The issue is caused by per NUMA node surplus pages
tracking (see free_huge_page).
Address both issues by changing the way how we allocate and account
pages allocated for migration. Those should temporal by definition. So
we mark them that way (we will abuse page flags in the 3rd page) and
update free_huge_page to free such pages to the page allocator. Page
migration path then just transfers the temporal status from the new page
to the old one which will be freed on the last reference. The global
surplus count will never change during this path but we still have to be
careful when migrating a per-node suprlus page. This is now handled in
move_hugetlb_state which is called from the migration path and it copies
the hugetlb specific page state and fixes up the accounting when needed
Rename __alloc_buddy_huge_page to __alloc_surplus_huge_page to better
reflect its purpose. The new allocation routine for the migration path
is __alloc_migrate_huge_page.
The user visible effect of this patch is that migrated pages are really
temporal and they travel between NUMA nodes as per the migration
request:
Before migration
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:1
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0
After
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/nr_hugepages:0
/sys/devices/system/node/node0/hugepages/hugepages-2048kB/surplus_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/free_hugepages:0
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/nr_hugepages:1
/sys/devices/system/node/node1/hugepages/hugepages-2048kB/surplus_hugepages:0
with the previous implementation, both nodes would have nr_hugepages:1
until the page is freed.
Link: http://lkml.kernel.org/r/20180103093213.26329-4-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:20:44 +0000 (16:20 -0800)]
mm, hugetlb: integrate giga hugetlb more naturally to the allocation path
Gigantic hugetlb pages were ingrown to the hugetlb code as an alien
specie with a lot of special casing. The allocation path is not an
exception. Unnecessarily so to be honest. It is true that the
underlying allocator is different but that is an implementation detail.
This patch unifies the hugetlb allocation path that a prepares fresh
pool pages. alloc_fresh_gigantic_page basically copies
alloc_fresh_huge_page logic so we can move everything there. This will
simplify set_max_huge_pages which doesn't have to care about what kind
of huge page we allocate.
Link: http://lkml.kernel.org/r/20180103093213.26329-3-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:20:41 +0000 (16:20 -0800)]
mm, hugetlb: unify core page allocation accounting and initialization
Patch series "mm, hugetlb: allocation API and migration improvements"
Motivation:
this is a follow up for [3] for the allocation API and [4] for the
hugetlb migration. It wasn't really easy to split those into two
separate patch series as they share some code.
My primary motivation to touch this code is to make the gigantic pages
migration working. The giga pages allocation code is just too fragile
and hacked into the hugetlb code now. This series tries to move giga
pages closer to the first class citizen. We are not there yet but
having 5 patches is quite a lot already and it will already make the
code much easier to follow. I will come with other changes on top after
this sees some review.
The first two patches should be trivial to review. The third patch
changes the way how we migrate huge pages. Newly allocated pages are a
subject of the overcommit check and they participate surplus accounting
which is quite unfortunate as the changelog explains. This patch
doesn't change anything wrt. giga pages.
Patch #4 removes the surplus accounting hack from
__alloc_surplus_huge_page. I hope I didn't miss anything there and a
deeper review is really due there.
Patch #5 finally unifies allocation paths and giga pages shouldn't be
any special anymore. There is also some renaming going on as well.
This patch (of 6):
hugetlb allocator has two entry points to the page allocator
- alloc_fresh_huge_page_node
- __hugetlb_alloc_buddy_huge_page
The two differ very subtly in two aspects. The first one doesn't care
about HTLB_BUDDY_* stats and it doesn't initialize the huge page.
prep_new_huge_page is not used because it not only initializes hugetlb
specific stuff but because it also put_page and releases the page to the
hugetlb pool which is not what is required in some contexts. This makes
things more complicated than necessary.
Simplify things by a) removing the page allocator entry point duplicity
and only keep __hugetlb_alloc_buddy_huge_page and b) make
prep_new_huge_page more reusable by removing the put_page which moves
the page to the allocator pool. All current callers are updated to call
put_page explicitly. Later patches will add new callers which won't
need it.
This patch shouldn't introduce any functional change.
Link: http://lkml.kernel.org/r/20180103093213.26329-2-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andrea Reale <ar@linux.vnet.ibm.com> Cc: Anshuman Khandual <khandual@linux.vnet.ibm.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Andrey Ryabinin [Thu, 1 Feb 2018 00:20:37 +0000 (16:20 -0800)]
mm/memcontrol.c: try harder to decrease [memory,memsw].limit_in_bytes
mem_cgroup_resize_[memsw]_limit() tries to free only 32
(SWAP_CLUSTER_MAX) pages on each iteration. This makes it practically
impossible to decrease limit of memory cgroup. Tasks could easily
allocate back 32 pages, so we can't reduce memory usage, and once
retry_count reaches zero we return -EBUSY.
Easy to reproduce the problem by running the following commands:
Instead of relying on retry_count, keep retrying the reclaim until the
desired limit is reached or fail if the reclaim doesn't make any
progress or a signal is pending.
Link: http://lkml.kernel.org/r/20180119132544.19569-1-aryabinin@virtuozzo.com Signed-off-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Acked-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Shakeel Butt <shakeelb@google.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Vladimir Davydov <vdavydov.dev@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ralph Campbell [Thu, 1 Feb 2018 00:20:30 +0000 (16:20 -0800)]
mm/hmm: fix uninitialized use of 'entry' in hmm_vma_walk_pmd()
The variable 'entry' is used before being initialized in
hmm_vma_walk_pmd().
No bad effect (beside performance hit) so !non_swap_entry(0) evaluate to
true which trigger a fault as if CPU was trying to access migrated
memory and migrate memory back from device memory to regular memory.
This function (hmm_vma_walk_pmd()) is called when a device driver tries
to populate its own page table. For migrated memory it should not
happen as the device driver should already have populated its page table
correctly during the migration.
Only case I can think of is multi-GPU where a second GPU triggers
migration back to regular memory. Again this would just result in a
performance hit, nothing bad would happen.
Link: http://lkml.kernel.org/r/20180122185759.26286-1-jglisse@redhat.com Signed-off-by: Ralph Campbell <rcampbell@nvidia.com> Signed-off-by: Jérôme Glisse <jglisse@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Petr Tesarik [Thu, 1 Feb 2018 00:20:26 +0000 (16:20 -0800)]
include/linux/mmzone.h: fix explanation of lower bits in the SPARSEMEM mem_map pointer
The comment is confusing. On the one hand, it refers to 32-bit
alignment (struct page alignment on 32-bit platforms), but this would
only guarantee that the 2 lowest bits must be zero. On the other hand,
it claims that at least 3 bits are available, and 3 bits are actually
used.
This is not broken, because there is a stronger alignment guarantee,
just less obvious. Let's fix the comment to make it clear how many bits
are available and why.
Although memmap arrays are allocated in various places, the resulting
pointer is encoded eventually, so I am adding a BUG_ON() here to enforce
at runtime that all expected bits are indeed available.
I have also added a BUILD_BUG_ON to check that PFN_SECTION_SHIFT is
sufficient, because this part of the calculation can be easily checked
at build time.
[ptesarik@suse.com: v2] Link: http://lkml.kernel.org/r/20180125100516.589ea6af@ezekiel.suse.cz Link: http://lkml.kernel.org/r/20180119080908.3a662e6f@ezekiel.suse.cz Signed-off-by: Petr Tesarik <ptesarik@suse.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Kemi Wang <kemi.wang@intel.com> Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yang Shi [Thu, 1 Feb 2018 00:20:23 +0000 (16:20 -0800)]
mm/compaction.c: fix comment for try_to_compact_pages()
"mode" argument is not used by try_to_compact_pages() and sub functions
anymore, it has been replaced by "prio". Fix the comment to explain the
use of "prio" argument.
Link: http://lkml.kernel.org/r/1515801336-20611-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
but for it to work, CONFIG_DEBUG_PAGEALLOC must be enabled first. If
someone has CONFIG_PAGE_EXTENSION, but has none of its users, eg:
(CONFIG_PAGE_OWNER, CONFIG_DEBUG_PAGEALLOC, CONFIG_IDLE_PAGE_TRACKING),
we can shrink page_ext_init() to a simple retq.
On the other hand, it might does not even make sense, since if someone
enables CONFIG_PAGE_EXTENSION, I would expect him to enable also at
least one of its users.
Link: http://lkml.kernel.org/r/20180105130235.GA21241@techadventures.net Signed-off-by: Oscar Salvador <osalvador@techadventures.net> Cc: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Jaewon Kim <jaewon31.kim@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yu Zhao [Thu, 1 Feb 2018 00:20:02 +0000 (16:20 -0800)]
memcg: refactor mem_cgroup_resize_limit()
mem_cgroup_resize_limit() and mem_cgroup_resize_memsw_limit() have
identical logics. Refactor code so we don't need to keep two pieces of
code that does same thing.
Link: http://lkml.kernel.org/r/20180108224238.14583-1-yuzhao@google.com Signed-off-by: Yu Zhao <yuzhao@google.com> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
shidao.ytt [Thu, 1 Feb 2018 00:19:55 +0000 (16:19 -0800)]
mm/fadvise: discard partial page if endbyte is also EOF
During our recent testing with fadvise(FADV_DONTNEED), we find that if
given offset/length is not page-aligned, the last page will not be
discarded. The tool we use is vmtouch (https://hoytech.com/vmtouch/),
we map a 10KB-sized file into memory and then try to run this tool to
evict the whole file mapping, but the last single page always remains
staying in the memory:
After digging a little bit into this problem, we find it seems not a
regression. Not discarding partial page is likely to be on purpose
according to commit 441c228f817f ("mm: fadvise: document the
fadvise(FADV_DONTNEED) behaviour for partial pages") written by Mel
Gorman. He explained why partial pages should be preserved instead of
being discarded when using fadvise(FADV_DONTNEED).
However, the interesting part is that the actual code did NOT work as
the same as it was described, the partial page was still discarded
anyway, due to a calculation mistake of `end_index' passed to
invalidate_mapping_pages(). This mistake has not been fixed until
recently, that's why we fail to reproduce our problem in old kernels.
The fix is done in commit 18aba41cbf ("mm/fadvise.c: do not discard
partial pages with POSIX_FADV_DONTNEED") by Oleg Drokin.
Back to the original testing, our problem becomes that there is a
special case that, if the page-unaligned `endbyte' is also the end of
file, it is not necessary at all to preserve the last partial page, as
we all know no one else will use the rest of it. It should be safe
enough if we just discard the whole page. So we add an EOF check in
this patch.
We also find a poosbile real world issue in mainline kernel. Assume
such scenario: A userspace backup application want to backup a huge
amount of small files (<4k) at once, the developer might (I guess) want
to use fadvise(FADV_DONTNEED) to save memory. However, FADV_DONTNEED
won't really happen since the only page mapped is a partial page, and
kernel will preserve it. Our patch also fixes this problem, since we
know the endbyte is EOF, so we discard it.
Here is a simple reproducer to reproduce and verify each scenario we
described above:
Mel Gorman [Thu, 1 Feb 2018 00:19:52 +0000 (16:19 -0800)]
mm: pin address_space before dereferencing it while isolating an LRU page
Minchan Kim asked the following question -- what locks protects
address_space destroying when race happens between inode trauncation and
__isolate_lru_page? Jan Kara clarified by describing the race as follows
CPU1 CPU2
truncate(inode) __isolate_lru_page()
...
truncate_inode_page(mapping, page);
delete_from_page_cache(page)
spin_lock_irqsave(&mapping->tree_lock, flags);
__delete_from_page_cache(page, NULL)
page_cache_tree_delete(..)
... mapping = page_mapping(page);
page->mapping = NULL;
...
spin_unlock_irqrestore(&mapping->tree_lock, flags);
page_cache_free_page(mapping, page)
put_page(page)
if (put_page_testzero(page)) -> false
- inode now has no pages and can be freed including embedded address_space
if (mapping && !mapping->a_ops->migratepage)
- we've dereferenced mapping which is potentially already free.
The race is theoretically possible but unlikely. Before the
delete_from_page_cache, truncate_cleanup_page is called so the page is
likely to be !PageDirty or PageWriteback which gets skipped by the only
caller that checks the mappping in __isolate_lru_page. Even if the race
occurs, a substantial amount of work has to happen during a tiny window
with no preemption but it could potentially be done using a virtual
machine to artifically slow one CPU or halt it during the critical
window.
This patch should eliminate the race with truncation by try-locking the
page before derefencing mapping and aborting if the lock was not
acquired. There was a suggestion from Huang Ying to use RCU as a
side-effect to prevent mapping being freed. However, I do not like the
solution as it's an unconventional means of preserving a mapping and
it's not a context where rcu_read_lock is obviously protecting rcu data.
Link: http://lkml.kernel.org/r/20180104102512.2qos3h5vqzeisrek@techsingularity.net Fixes: c82449352854 ("mm: compaction: make isolate_lru_page() filter-aware again") Signed-off-by: Mel Gorman <mgorman@techsingularity.net> Acked-by: Minchan Kim <minchan@kernel.org> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Jan Kara <jack@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Eric Biggers [Thu, 1 Feb 2018 00:19:48 +0000 (16:19 -0800)]
userfaultfd: convert to use anon_inode_getfd()
Nothing actually calls userfaultfd_file_create() besides the
userfaultfd() system call itself. So simplify things by folding it into
the system call and using anon_inode_getfd() instead of
anon_inode_getfile(). Do the same in resolve_userfault_fork() as well.
This removes over 50 lines with no change in functionality.
Link: http://lkml.kernel.org/r/20171229212403.22800-1-ebiggers3@gmail.com Signed-off-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Implements memfd sealing, similar to shmem:
- WRITE: deny fallocate(PUNCH_HOLE). mmap() write is denied in
memfd_add_seals(). write() doesn't exist for hugetlbfs.
- SHRINK: added similar check as shmem_setattr()
- GROW: added similar check as shmem_setattr() & shmem_fallocate()
Except write() operation that doesn't exist with hugetlbfs, that should
make sealing as close as it can be to shmem support.
Link: http://lkml.kernel.org/r/20171107122800.25517-5-marcandre.lureau@redhat.com Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hugetlbfs inode information will need to be accessed by code in
mm/shmem.c for file sealing operations. Move inode information
definition from .c file to header for needed access.
Link: http://lkml.kernel.org/r/20171107122800.25517-4-marcandre.lureau@redhat.com Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "memfd: add sealing to hugetlb-backed memory", v3.
Recently, Mike Kravetz added hugetlbfs support to memfd. However, he
didn't add sealing support. One of the reasons to use memfd is to have
shared memory sealing when doing IPC or sharing memory with another
process with some extra safety. qemu uses shared memory & hugetables
with vhost-user (used by dpdk), so it is reasonable to use memfd now
instead for convenience and security reasons.
This patch (of 9):
The functions are called through shmem_fcntl() only. And no danger in
removing the EXPORTs as the routines only work with shmem file structs.
Link: http://lkml.kernel.org/r/20171107122800.25517-2-marcandre.lureau@redhat.com Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: David Herrmann <dh.herrmann@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Matthew Wilcox [Thu, 1 Feb 2018 00:19:02 +0000 (16:19 -0800)]
mm: store compound_dtor / compound_order as bytes
Neither of these values get even close to 256; compound_dtor is
currently at a maximum of 3, and compound_order can't be over 64. No
machine has inefficient access to bytes since EV5, and while those are
still supported, we don't optimise for them any more. This does not
shrink struct page, but it removes an ifdef and frees up 2-6 bytes for
future use.
Matthew Wilcox [Thu, 1 Feb 2018 00:18:58 +0000 (16:18 -0800)]
mm: introduce _slub_counter_t
Instead of putting the ifdef in the middle of the definition of struct
page, pull it forward to the rest of the ifdeffery around the SLUB
cmpxchg_double optimisation.
Link: http://lkml.kernel.org/r/20171220155552.15884-6-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Christoph Lameter <cl@linux.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Matthew Wilcox [Thu, 1 Feb 2018 00:18:55 +0000 (16:18 -0800)]
mm: improve comment on page->mapping
The comment on page->mapping is terse, and out of date (it does not
mention the possibility of PAGE_MAPPING_MOVABLE). Instead, point the
interested reader to page-flags.h where there is a much better comment.
Link: http://lkml.kernel.org/r/20171220155552.15884-5-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
which is 32 bytes on 64-bit, but 20 bytes on 32-bit. Nobody is trying to
use the fact that it's double-word aligned today, so just remove the
misleading claims.
Link: http://lkml.kernel.org/r/20171220155552.15884-4-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Matthew Wilcox [Thu, 1 Feb 2018 00:18:47 +0000 (16:18 -0800)]
mm: de-indent struct page
I found the struct { union { struct { union { struct { } } } } } layout
rather confusing. Fortunately, there is an easier way to write this.
The innermost union is of four things which are the size of an int, so
the ones which are used by slab/slob/slub can be pulled up two levels to
be in the outermost union with 'counters'. That leaves us with struct {
union { struct { atomic_t; atomic_t; } } } which has the same layout,
but is easier to read.
Output from the current git version of pahole, diffed with -uw to ignore
the whitespace changes from the indentation:
Matthew Wilcox [Thu, 1 Feb 2018 00:18:44 +0000 (16:18 -0800)]
mm: align struct page more aesthetically
Patch series "Restructure struct page", v2.
This series does not attempt any grand restructuring. Instead, it cures
the worst of the indentitis, fixes the documentation and reduces the
ifdeffery. The only layout change is compound_dtor and compound_order
are each reduced to one byte.
This patch (of 8):
Instead of an ifdef block at the end of the struct, which needed its own
comment, define _struct_page_alignment up at the top where it fits
nicely with the existing comment.
Link: http://lkml.kernel.org/r/20171220155552.15884-2-willy@infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Christoph Lameter <cl@linux.com> Cc: Randy Dunlap <rdunlap@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Structure zs_pool has special flag to indicate success of shrinker
initialization. unregister_shrinker() has improved and can detect by
itself whether actual deinitialization should be performed or not, so
extra flag becomes redundant.
David Rientjes [Thu, 1 Feb 2018 00:18:36 +0000 (16:18 -0800)]
mm, oom: avoid reaping only for mm's with blockable invalidate callbacks
This uses the new annotation to determine if an mm has mmu notifiers
with blockable invalidate range callbacks to avoid oom reaping.
Otherwise, the callbacks are used around unmap_page_range().
Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1712141330120.74052@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Christian König <christian.koenig@amd.com> Cc: Dimitri Sivanich <sivanich@hpe.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: David Airlie <airlied@linux.ie> Cc: Joerg Roedel <joro@8bytes.org> Cc: Doug Ledford <dledford@redhat.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Mike Marciniszyn <mike.marciniszyn@intel.com> Cc: Sean Hefty <sean.hefty@intel.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
David Rientjes [Thu, 1 Feb 2018 00:18:32 +0000 (16:18 -0800)]
mm, mmu_notifier: annotate mmu notifiers with blockable invalidate callbacks
Commit 4d4bbd8526a8 ("mm, oom_reaper: skip mm structs with mmu
notifiers") prevented the oom reaper from unmapping private anonymous
memory with the oom reaper when the oom victim mm had mmu notifiers
registered.
The rationale is that doing mmu_notifier_invalidate_range_{start,end}()
around the unmap_page_range(), which is needed, can block and the oom
killer will stall forever waiting for the victim to exit, which may not
be possible without reaping.
That concern is real, but only true for mmu notifiers that have
blockable invalidate_range_{start,end}() callbacks. This patch adds a
"flags" field to mmu notifier ops that can set a bit to indicate that
these callbacks do not block.
The implementation is steered toward an expensive slowpath, such as
after the oom reaper has grabbed mm->mmap_sem of a still alive oom
victim.
[rientjes@google.com: mmu_notifier_invalidate_range_end() can also call the invalidate_range() must not block, fix comment] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1801091339570.240101@chino.kir.corp.google.com
[akpm@linux-foundation.org: make mm_has_blockable_invalidate_notifiers() return bool, use rwsem_is_locked()] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1712141329500.74052@chino.kir.corp.google.com Signed-off-by: David Rientjes <rientjes@google.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Paolo Bonzini <pbonzini@redhat.com> Acked-by: Christian König <christian.koenig@amd.com> Acked-by: Dimitri Sivanich <sivanich@hpe.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Oded Gabbay <oded.gabbay@gmail.com> Cc: Alex Deucher <alexander.deucher@amd.com> Cc: David Airlie <airlied@linux.ie> Cc: Joerg Roedel <joro@8bytes.org> Cc: Doug Ledford <dledford@redhat.com> Cc: Jani Nikula <jani.nikula@linux.intel.com> Cc: Mike Marciniszyn <mike.marciniszyn@intel.com> Cc: Sean Hefty <sean.hefty@intel.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Jérôme Glisse <jglisse@redhat.com> Cc: Radim Krčmář <rkrcmar@redhat.com> Signed-off-by: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yang Shi [Thu, 1 Feb 2018 00:18:28 +0000 (16:18 -0800)]
mm: thp: use down_read_trylock() in khugepaged to avoid long block
In the current design, khugepaged needs to acquire mmap_sem before
scanning an mm. But in some corner cases, khugepaged may scan a process
which is modifying its memory mapping, so khugepaged blocks in
uninterruptible state. But the process might hold the mmap_sem for a
long time when modifying a huge memory space and it may trigger the
below khugepaged hung issue:
So it sounds pointless to just block khugepaged waiting for the
semaphore so replace down_read() with down_read_trylock() to move to
scan the next mm quickly instead of just blocking on the semaphore so
that other processes can get more chances to install THP. Then
khugepaged can come back to scan the skipped mm when it has finished the
current round full_scan.
And it appears that the change can improve khugepaged efficiency a
little bit.
Below is the test result when running LTP on a 24 cores 4GB memory 2
nodes NUMA VM:
Instead of marking the pmd ready for split, invalidate the pmd. This
should take care of powerpc requirement. Only side effect is that we
mark the pmd invalid early. This can result in us blocking access to
the page a bit longer if we race against a thp split.
[kirill.shutemov@linux.intel.com: rebased, dirty THP once] Link: http://lkml.kernel.org/r/20171213105756.69879-13-kirill.shutemov@linux.intel.com Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Daney <david.daney@cavium.com> Cc: David Miller <davem@davemloft.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nitin Gupta <nitin.m.gupta@oracle.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: do not lose dirty and accessed bits in pmdp_invalidate()
Vlastimil noted that pmdp_invalidate() is not atomic and we can lose
dirty and access bits if CPU sets them after pmdp dereference, but
before set_pmd_at().
The patch change pmdp_invalidate() to make the entry non-present
atomically and return previous value of the entry. This value can be
used to check if CPU set dirty/accessed bits under us.
The race window is very small and I haven't seen any reports that can be
attributed to the bug. For this reason, I don't think backporting to
stable trees needed.
Link: http://lkml.kernel.org/r/20171213105756.69879-11-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Reported-by: Vlastimil Babka <vbabka@suse.cz> Cc: Hugh Dickins <hughd@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Daney <david.daney@cavium.com> Cc: David Miller <davem@davemloft.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Nitin Gupta <nitin.m.gupta@oracle.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We need an atomic way to setup pmd page table entry, avoiding races with
CPU setting dirty/accessed bits. This is required to implement
pmdp_invalidate() that doesn't lose these bits.
On PAE we can avoid expensive cmpxchg8b for cases when new page table
entry is not present. If it's present, fallback to cpmxchg loop.
[akpm@linux-foundation.org: add missing `do' to do-while loop] Link: http://lkml.kernel.org/r/20171213105756.69879-10-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nitin Gupta [Thu, 1 Feb 2018 00:18:09 +0000 (16:18 -0800)]
sparc64: update pmdp_invalidate() to return old pmd value
It's required to avoid losing dirty and accessed bits.
[akpm@linux-foundation.org: add a `do' to the do-while loop] Link: http://lkml.kernel.org/r/20171213105756.69879-9-kirill.shutemov@linux.intel.com Signed-off-by: Nitin Gupta <nitin.m.gupta@oracle.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: David Miller <davem@davemloft.net> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Catalin Marinas [Thu, 1 Feb 2018 00:17:55 +0000 (16:17 -0800)]
arm64: provide pmdp_establish() helper
We need an atomic way to setup pmd page table entry, avoiding races with
CPU setting dirty/accessed bits. This is required to implement
pmdp_invalidate() that doesn't lose these bits.
Link: http://lkml.kernel.org/r/20171213105756.69879-5-kirill.shutemov@linux.intel.com Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Patch series "Do not lose dirty bit on THP pages", v4.
Vlastimil noted that pmdp_invalidate() is not atomic and we can lose
dirty and access bits if CPU sets them after pmdp dereference, but
before set_pmd_at().
The bug can lead to data loss, but the race window is tiny and I haven't
seen any reports that suggested that it happens in reality. So I don't
think it worth sending it to stable.
Unfortunately, there's no way to address the issue in a generic way. We
need to fix all architectures that support THP one-by-one.
All architectures that have THP supported have to provide atomic
pmdp_invalidate() that returns previous value.
If generic implementation of pmdp_invalidate() is used, architecture
needs to provide atomic pmdp_estabish().
pmdp_estabish() is not used out-side generic implementation of
pmdp_invalidate() so far, but I think this can change in the future.
This patch (of 12):
This is an implementation of pmdp_establish() that is only suitable for
an architecture that doesn't have hardware dirty/accessed bits. In this
case we can't race with CPU which sets these bits and non-atomic
approach is fine.
Link: http://lkml.kernel.org/r/20171213105756.69879-2-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Daney <david.daney@cavium.com> Cc: David Miller <davem@davemloft.net> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Nitin Gupta <nitin.m.gupta@oracle.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vineet Gupta <vgupta@synopsys.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Matthew Wilcox [Thu, 1 Feb 2018 00:17:40 +0000 (16:17 -0800)]
mm: get 7% more pages in a pagevec
We don't have to use an entire 'long' for the number of elements in the
pagevec; we know it's a number between 0 and 14 (now 15). So we can
store it in a char, and then the bool packs next to it and we still have
two or six bytes of padding for more elements in the header. That gives
us space to cram in an extra page.
Link: http://lkml.kernel.org/r/20171206022521.GM26021@bombadil.infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Matthew Wilcox [Thu, 1 Feb 2018 00:17:36 +0000 (16:17 -0800)]
mm: add unmap_mapping_pages()
Several users of unmap_mapping_range() would prefer to express their
range in pages rather than bytes. Unfortuately, on a 32-bit kernel, you
have to remember to cast your page number to a 64-bit type before
shifting it, and four places in the current tree didn't remember to do
that. That's a sign of a bad interface.
Conveniently, unmap_mapping_range() actually converts from bytes into
pages, so hoist the guts of unmap_mapping_range() into a new function
unmap_mapping_pages() and convert the callers which want to use pages.
Link: http://lkml.kernel.org/r/20171206142627.GD32044@bombadil.infradead.org Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com> Reported-by: "zhangyi (F)" <yi.zhang@huawei.com> Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Huang Ying [Thu, 1 Feb 2018 00:17:32 +0000 (16:17 -0800)]
mm, userfaultfd, THP: avoid waiting when PMD under THP migration
If THP migration is enabled, for a VMA handled by userfaultfd, consider
the following situation,
do_page_fault()
__do_huge_pmd_anonymous_page()
handle_userfault()
userfault_msg()
/* a huge page is allocated and mapped at fault address */
/* the huge page is under migration, leaves migration entry
in page table */
userfaultfd_must_wait()
/* return true because !pmd_present() */
/* may wait in loop until fatal signal */
That is, it may be possible for userfaultfd_must_wait() encounters a PMD
entry which is !pmd_none() && !pmd_present(). In the current
implementation, we will wait for such PMD entries, which may cause
unnecessary waiting, and potential soft lockup.
This is fixed via avoiding to wait when !pmd_none() && !pmd_present(),
only wait when pmd_none().
This may be not a problem in practice, because userfaultfd_must_wait()
is always called with mm->mmap_sem read-locked. mremap() will
write-lock mm->mmap_sem. And UFFDIO_COPY doesn't support to copy THP
mapping. But the change introduced still makes the code more correct,
and makes the PMD and PTE code more consistent.
Link: http://lkml.kernel.org/r/20171207011752.3292-1-ying.huang@intel.com Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Cc: Mike Rapoport <rppt@linux.vnet.ibm.com> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Alexander Viro <viro@zeniv.linux.org.UK> Cc: Zi Yan <zi.yan@cs.rutgers.edu> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Oscar Salvador [Thu, 1 Feb 2018 00:17:25 +0000 (16:17 -0800)]
mm: memory_hotplug: remove second __nr_to_section in register_page_bootmem_info_section()
In register_page_bootmem_info_section() we call __nr_to_section() in
order to get the mem_section struct at the beginning of the function.
Since we already got it, there is no need for a second call to
__nr_to_section().
Link: http://lkml.kernel.org/r/20171207102914.GA12396@techadventures.net Signed-off-by: Oscar Salvador <osalvador@techadventures.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
VmExe and VmLib documented as text segment and shared library code size.
Now their sum will be always equal to mm->exec_vm which sums size of
executable and not writable and not stack areas.
I've seen this for huge (>2Gb) statically linked binary which has whole
world inside. For it start_code .. end_code range also covers one of
rodata sections. Probably this is bug in customized linker, elf loader
or both.
Anyway CONFIG_CHECKPOINT_RESTORE allows to change these pointers, thus
we cannot trust them without validation.
Link: http://lkml.kernel.org/r/150728955451.743749.11276392315459539583.stgit@buzz Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Acked-by: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Oscar Salvador [Thu, 1 Feb 2018 00:17:14 +0000 (16:17 -0800)]
mm/memory_hotplug.c: remove unnecesary check from register_page_bootmem_info_section()
When we call register_page_bootmem_info_section() having
CONFIG_SPARSEMEM_VMEMMAP enabled, we check if the pfn is valid.
This check is redundant as we already checked this in
register_page_bootmem_info_node() before calling
register_page_bootmem_info_section(), so let's get rid of it.
Link: http://lkml.kernel.org/r/20171205143422.GA31458@techadventures.net Signed-off-by: Oscar Salvador <osalvador@techadventures.net> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Michal Hocko [Thu, 1 Feb 2018 00:17:10 +0000 (16:17 -0800)]
mm, hugetlb: remove hugepages_treat_as_movable sysctl
hugepages_treat_as_movable has been introduced by 396faf0303d2 ("Allow
huge page allocations to use GFP_HIGH_MOVABLE") to allow hugetlb
allocations from ZONE_MOVABLE even when hugetlb pages were not
migrateable. The purpose of the movable zone was different at the time.
It aimed at reducing memory fragmentation and hugetlb pages being long
lived and large werre not contributing to the fragmentation so it was
acceptable to use the zone back then.
Things have changed though and the primary purpose of the zone became
migratability guarantee. If we allow non migrateable hugetlb pages to
be in ZONE_MOVABLE memory hotplug might fail to offline the memory.
Remove the knob and only rely on hugepage_migration_supported to allow
movable zones.
Mel said:
: Primarily it was aimed at allowing the hugetlb pool to safely shrink with
: the ability to grow it again. The use case was for batched jobs, some of
: which needed huge pages and others that did not but didn't want the memory
: useless pinned in the huge pages pool.
:
: I suspect that more users rely on THP than hugetlbfs for flexible use of
: huge pages with fallback options so I think that removing the option
: should be ok.
Link: http://lkml.kernel.org/r/20171003072619.8654-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Reported-by: Alexandru Moise <00moses.alexander00@gmail.com> Acked-by: Mel Gorman <mgorman@suse.de> Cc: Alexandru Moise <00moses.alexander00@gmail.com> Cc: Mike Kravetz <mike.kravetz@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jan Kara [Thu, 1 Feb 2018 00:17:06 +0000 (16:17 -0800)]
mm: remove unused pgdat_reclaimable_pages()
Remove unused function pgdat_reclaimable_pages() and
node_page_state_snapshot() which becomes unused as well.
Link: http://lkml.kernel.org/r/20171122094416.26019-1-jack@suse.cz Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
selftests/vm: move 128TB mmap boundary test to generic directory
Architectures like PPC64 support mmap hint address based large address
space selection. This test can be run on those architectures too. Move
the test from the x86 selftests to selftest/vm so that other
architectures can use it too.
We also add a few new test scenarios in this patch. We do test a few
boundary conditions before we do a high address mmap. PPC64 uses the
address limit to validate the address in the fault path. We had bugs in
this area w.r.t SLB fault handling before we updated the addess limit.
We also touch the allocated space to make sure we don't have any bugs in
the fault handling path.
Minchan Kim [Thu, 1 Feb 2018 00:16:55 +0000 (16:16 -0800)]
mm: do not stall register_shrinker()
Shakeel Butt reported he has observed in production systems that the job
loader gets stuck for 10s of seconds while doing a mount operation. It
turns out that it was stuck in register_shrinker() because some
unrelated job was under memory pressure and was spending time in
shrink_slab(). Machines have a lot of shrinkers registered and jobs
under memory pressure have to traverse all of those memcg-aware
shrinkers and affect unrelated jobs which want to register their own
shrinkers.
To solve the issue, this patch simply bails out slab shrinking if it is
found that someone wants to register a shrinker in parallel. A downside
is it could cause unfair shrinking between shrinkers. However, it
should be rare and we can add compilcated logic if we find it's not
enough.
Jiankang Chen [Thu, 1 Feb 2018 00:16:52 +0000 (16:16 -0800)]
mm/page_alloc.c: fix comment in __get_free_pages()
__get_free_pages() will return a virtual address, but it is not just a
32-bit address, for example on a 64-bit system. And this comment really
confuses new readers of mm.
Link: http://lkml.kernel.org/r/1511780964-64864-1-git-send-email-chenjiankang1@huawei.com Signed-off-by: Jiankang Chen <chenjiankang1@huawei.com> Reported-by: Hanjun Guo <guohanjun@huawei.com> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Yisheng Xie <xieyisheng1@huawei.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Johannes Weiner [Thu, 1 Feb 2018 00:16:45 +0000 (16:16 -0800)]
mm: memcontrol: fix excessive complexity in memory.stat reporting
We've seen memory.stat reads in top-level cgroups take up to fourteen
seconds during a userspace bug that created tens of thousands of ghost
cgroups pinned by lingering page cache.
Even with a more reasonable number of cgroups, aggregating memory.stat
is unnecessarily heavy. The complexity is this:
nr_cgroups * nr_stat_items * nr_possible_cpus
where the stat items are ~70 at this point. With 128 cgroups and 128
CPUs - decent, not enormous setups - reading the top-level memory.stat
has to aggregate over a million per-cpu counters. This doesn't scale.
Instead of spreading the source of truth across all CPUs, use the
per-cpu counters merely to batch updates to shared atomic counters.
This is the same as the per-cpu stocks we use for charging memory to the
shared atomic page_counters, and also the way the global vmstat counters
are implemented.
Vmstat has elaborate spilling thresholds that depend on the number of
CPUs, amount of memory, and memory pressure - carefully balancing the
cost of counter updates with the amount of per-cpu error. That's
because the vmstat counters are system-wide, but also used for decisions
inside the kernel (e.g. NR_FREE_PAGES in the allocator). Neither is
true for the memory controller.
Use the same static batch size we already use for page_counter updates
during charging. The per-cpu error in the stats will be 128k, which is
an acceptable ratio of cores to memory accounting granularity.
Johannes Weiner [Thu, 1 Feb 2018 00:16:41 +0000 (16:16 -0800)]
mm: memcontrol: implement lruvec stat functions on top of each other
The implementation of the lruvec stat functions and their variants for
accounting through a page, or accounting from a preemptible context, are
mostly identical and needlessly repetitive.
Implement the lruvec_page functions by looking up the page's lruvec and
then using the lruvec function.
Implement the functions for preemptible contexts by disabling preemption
before calling the atomic context functions.
Link: http://lkml.kernel.org/r/20171103153336.24044-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Vladimir Davydov <vdavydov.dev@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yang Shi [Thu, 1 Feb 2018 00:16:34 +0000 (16:16 -0800)]
mm/filemap.c: remove include of hardirq.h
in_atomic() has been moved to include/linux/preempt.h, and the filemap.c
doesn't use in_atomic() directly at all, so it sounds unnecessary to
include hardirq.h.
Pavel Tatashin [Thu, 1 Feb 2018 00:16:30 +0000 (16:16 -0800)]
mm: split deferred_init_range into initializing and freeing parts
In deferred_init_range() we initialize struct pages, and also free them
to buddy allocator. We do it in separate loops, because buddy page is
computed ahead, so we do not want to access a struct page that has not
been initialized yet.
There is still, however, a corner case where it is potentially possible
to access uninitialized struct page: this is when buddy page is from the
next memblock range.
This patch fixes this problem by splitting deferred_init_range() into
two functions: one to initialize struct pages, and another to free them.
In addition, this patch brings the following improvements:
- Get rid of __def_free() helper function. And simplifies loop logic by
adding a new pfn validity check function: deferred_pfn_valid().
- Reduces number of variables that we track. So, there is a higher
chance that we will avoid using stack to store/load variables inside
hot loops.
- Enables future multi-threading of these functions: do initialization
in multiple threads, wait for all threads to finish, do freeing part
in multithreading.
Tested on x86 with 1T of memory to make sure no regressions are
introduced.
[akpm@linux-foundation.org: fix spello in comment] Link: http://lkml.kernel.org/r/20171107150446.32055-2-pasha.tatashin@oracle.com Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Steven Sistare <steven.sistare@oracle.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Josef Bacik [Thu, 1 Feb 2018 00:16:26 +0000 (16:16 -0800)]
mm: use sc->priority for slab shrink targets
Previously we were using the ratio of the number of lru pages scanned to
the number of eligible lru pages to determine the number of slab objects
to scan. The problem with this is that these two things have nothing to
do with each other, so in slab heavy work loads where there is little to
no page cache we can end up with the pages scanned being a very low
number. This means that we reclaim next to no slab pages and waste a
lot of time reclaiming small amounts of space.
Consider the following scenario, where we have the following values and
the rest of the memory usage is in slab
Active: 58840 kB
Inactive: 46860 kB
Every time we do a get_scan_count() we do this
scan = size >> sc->priority
where sc->priority starts at DEF_PRIORITY, which is 12. The first loop
through reclaim would result in a scan target of 2 pages to 11715 total
inactive pages, and 3 pages to 14710 total active pages. This is a
really really small target for a system that is entirely slab pages.
And this is super optimistic, this assumes we even get to scan these
pages. We don't increment sc->nr_scanned unless we 1) isolate the page,
which assumes it's not in use, and 2) can lock the page. Under pressure
these numbers could probably go down, I'm sure there's some random pages
from daemons that aren't actually in use, so the targets get even
smaller.
Instead use sc->priority in the same way we use it to determine scan
amounts for the lru's. This generally equates to pages. Consider the
following
but we don't know the number of slab pages each shrinker controls, only
the objects. However say that theoretically we knew how many pages a
shrinker controlled, we'd still have to convert this to objects, which
would look like the following
We don't need to know exactly how many pages each shrinker represents,
it's objects are all the information we need. Making this change allows
us to place an appropriate amount of pressure on the shrinker pools for
their relative size.
Link: http://lkml.kernel.org/r/1510780549-6812-1-git-send-email-josef@toxicpanda.com Signed-off-by: Josef Bacik <jbacik@fb.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Dave Chinner <david@fromorbit.com> Acked-by: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Michal Hocko <mhocko@kernel.org> Cc: Christoph Lameter <cl@linux.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: David Rientjes <rientjes@google.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Roman Gushchin [Thu, 1 Feb 2018 00:16:22 +0000 (16:16 -0800)]
mm: show total hugetlb memory consumption in /proc/meminfo
Currently we display some hugepage statistics (total, free, etc) in
/proc/meminfo, but only for default hugepage size (e.g. 2Mb).
If hugepages of different sizes are used (like 2Mb and 1Gb on x86-64),
/proc/meminfo output can be confusing, as non-default sized hugepages
are not reflected at all, and there are no signs that they are existing
and consuming system memory.
To solve this problem, let's display the total amount of memory,
consumed by hugetlb pages of all sized (both free and used). Let's call
it "Hugetlb", and display size in kB to match generic /proc/meminfo
style.
Michal Hocko [Thu, 1 Feb 2018 00:16:19 +0000 (16:16 -0800)]
mm: drop hotplug lock from lru_add_drain_all()
Pulling cpu hotplug locks inside the mm core function like
lru_add_drain_all just asks for problems and the recent lockdep splat
[1] just proves this. While the usage in that particular case might be
wrong we should avoid the locking as lru_add_drain_all() is used in many
places. It seems that this is not all that hard to achieve actually.
We have done the same thing for drain_all_pages which is analogous by
commit a459eeb7b852 ("mm, page_alloc: do not depend on cpu hotplug locks
inside the allocator"). All we have to care about is to handle
- the work item might be executed on a different cpu in worker from
unbound pool so it doesn't run on pinned on the cpu
- we have to make sure that we do not race with page_alloc_cpu_dead
calling lru_add_drain_cpu
the first part is already handled because the worker calls lru_add_drain
which disables preemption when calling lru_add_drain_cpu on the local
cpu it is draining. The later is true because page_alloc_cpu_dead is
called on the controlling CPU after the hotplugged CPU vanished
completely.
[add a cpu hotplug locking interaction as per tglx] Link: http://lkml.kernel.org/r/20171116120535.23765-1-mhocko@kernel.org Signed-off-by: Michal Hocko <mhocko@suse.com> Acked-by: Thomas Gleixner <tglx@linutronix.de> Cc: Tejun Heo <tj@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Yisheng Xie [Thu, 1 Feb 2018 00:16:15 +0000 (16:16 -0800)]
mm/mempolicy: add nodes_empty check in SYSC_migrate_pages
As in manpage of migrate_pages, the errno should be set to EINVAL when
none of the node IDs specified by new_nodes are on-line and allowed by
the process's current cpuset context, or none of the specified nodes
contain memory. However, when test by following case:
The ret will be 0 and no errno is set. As the new_nodes is empty, we
should expect EINVAL as documented.
To fix the case like above, this patch check whether target nodes AND
current task_nodes is empty, and then check whether AND
node_states[N_MEMORY] is empty.
Link: http://lkml.kernel.org/r/1510882624-44342-4-git-send-email-xieyisheng1@huawei.com Signed-off-by: Yisheng Xie <xieyisheng1@huawei.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> Cc: Andi Kleen <ak@linux.intel.com> Cc: Chris Salls <salls@cs.ucsb.edu> Cc: Christopher Lameter <cl@linux.com> Cc: David Rientjes <rientjes@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Tan Xiaojun <tanxiaojun@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The new nodes specifies one or more node IDs that are greater than the
maximum supported node ID, however, the errno is not set to EINVAL as
expected.
As man pages of set_mempolicy[1], mbind[2], and migrate_pages[3]
mentioned, when nodemask specifies one or more node IDs that are greater
than the maximum supported node ID, the errno should set to EINVAL.
However, get_nodes only check whether the part of bits
[BITS_PER_LONG*BITS_TO_LONGS(MAX_NUMNODES), maxnode) is zero or not, and
remain [MAX_NUMNODES, BITS_PER_LONG*BITS_TO_LONGS(MAX_NUMNODES)
unchecked.
This patch is to check the bits of [MAX_NUMNODES, maxnode) in get_nodes
to let migrate_pages set the errno to EINVAL when nodemask specifies one
or more node IDs that are greater than the maximum supported node ID,
which follows the manpage's guide.
Pavel Tatashin [Thu, 1 Feb 2018 00:16:02 +0000 (16:16 -0800)]
mm: relax deferred struct page requirements
There is no need to have ARCH_SUPPORTS_DEFERRED_STRUCT_PAGE_INIT, as all
the page initialization code is in common code.
Also, there is no need to depend on MEMORY_HOTPLUG, as initialization
code does not really use hotplug memory functionality. So, we can
remove this requirement as well.
This patch allows to use deferred struct page initialization on all
platforms with memblock allocator.
Tested on x86, arm64, and sparc. Also, verified that code compiles on
PPC with CONFIG_MEMORY_HOTPLUG disabled.
Link: http://lkml.kernel.org/r/20171117014601.31606-1-pasha.tatashin@oracle.com Signed-off-by: Pavel Tatashin <pasha.tatashin@oracle.com> Acked-by: Heiko Carstens <heiko.carstens@de.ibm.com> [s390] Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com> Acked-by: Michael Ellerman <mpe@ellerman.id.au> Acked-by: Michal Hocko <mhocko@suse.com> Cc: Steven Sistare <steven.sistare@oracle.com> Cc: Daniel Jordan <daniel.m.jordan@oracle.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Reza Arbab <arbab@linux.vnet.ibm.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Mel Gorman <mgorman@techsingularity.net> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Zswap is a cache which compresses the pages that are being swapped out
and stores them into a dynamically allocated RAM-based memory pool.
Experiments have shown that around 10-20% of pages stored in zswap are
same-filled pages (i.e. contents of the page are all same), but these
pages are handled as normal pages by compressing and allocating memory
in the pool.
This patch adds a check in zswap_frontswap_store() to identify
same-filled page before compression of the page. If the page is a
same-filled page, set zswap_entry.length to zero, save the same-filled
value and skip the compression of the page and alloction of memory in
zpool. In zswap_frontswap_load(), check if value of zswap_entry.length
is zero corresponding to the page to be loaded. If zswap_entry.length
is zero, fill the page with same-filled value. This saves the
decompression time during load.
On a ARM Quad Core 32-bit device with 1.5GB RAM by launching and
relaunching different applications, out of ~64000 pages stored in zswap,
~11000 pages were same-value filled pages (including zero-filled pages)
and ~9000 pages were zero-filled pages.
An average of 17% of pages(including zero-filled pages) in zswap are
same-value filled pages and 14% pages are zero-filled pages. An average
of 3% of pages are same-filled non-zero pages.
The below table shows the execution time profiling with the patch.
Baseline With patch % Improvement
-----------------------------------------------------------------
*Zswap Store Time 26.5ms 18ms 32%
(of same value pages)
*Zswap Load Time
(of same value pages) 25.5ms 13ms 49%
-----------------------------------------------------------------
On Ubuntu PC with 2GB RAM, while executing kernel build and other test
scripts and running multimedia applications, out of 360000 pages stored
in zswap 78000(~22%) of pages were found to be same-value filled pages
(including zero-filled pages) and 64000(~17%) are zero-filled pages. So
an average of %5 of pages are same-filled non-zero pages.
The below table shows the execution time profiling with the patch.
Baseline With patch % Improvement
-----------------------------------------------------------------
*Zswap Store Time 91ms 74ms 19%
(of same value pages)
*Zswap Load Time 50ms 7.5ms 85%
(of same value pages)
-----------------------------------------------------------------
*The execution times may vary with test device used.
Dan said:
: I did test this patch out this week, and I added some instrumentation to
: check the performance impact, and tested with a small program to try to
: check the best and worst cases.
:
: When doing a lot of swap where all (or almost all) pages are same-value, I
: found this patch does save both time and space, significantly. The exact
: improvement in time and space depends on which compressor is being used,
: but roughly agrees with the numbers you listed.
:
: In the worst case situation, where all (or almost all) pages have the
: same-value *except* the final long (meaning, zswap will check each long on
: the entire page but then still have to pass the page to the compressor),
: the same-value check is around 10-15% of the total time spent in
: zswap_frontswap_store(). That's a not-insignificant amount of time, but
: it's not huge. Considering that most systems will probably be swapping
: pages that aren't similar to the worst case (although I don't have any
: data to know that), I'd say the improvement is worth the possible
: worst-case performance impact.
[srividya.dr@samsung.com: add memset_l instead of for loop] Link: http://lkml.kernel.org/r/20171018104832epcms5p1b2232e2236258de3d03d1344dde9fce0@epcms5p1 Signed-off-by: Srividya Desireddy <srividya.dr@samsung.com> Acked-by: Dan Streetman <ddstreet@ieee.org> Cc: Seth Jennings <sjenning@redhat.com> Cc: Pekka Enberg <penberg@kernel.org> Cc: Dinakar Reddy Pathireddy <dinakar.p@samsung.com> Cc: SHARAN ALLUR <sharan.allur@samsung.com> Cc: RAJIB BASU <rajib.basu@samsung.com> Cc: JUHUN KIM <juhunkim@samsung.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Timofey Titovets <nefelim4ag@gmail.com> Cc: Andi Kleen <ak@linux.intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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