Jiang Liu [Wed, 3 Jul 2013 22:04:16 +0000 (15:04 -0700)]
mm/um: prepare for removing num_physpages and simplify mem_init()
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:04:09 +0000 (15:04 -0700)]
mm/ppc: prepare for removing num_physpages and simplify mem_init()
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:57 +0000 (15:03 -0700)]
mm/hexagon: prepare for removing num_physpages and simplify mem_init()
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Richard Kuo <rkuo@codeaurora.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:51 +0000 (15:03 -0700)]
mm/blackfin: prepare for removing num_physpages and simplify mem_init()
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Mike Frysinger <vapier@gentoo.org> Cc: Bob Liu <lliubbo@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:49 +0000 (15:03 -0700)]
mm/ARM64: prepare for removing num_physpages and simplify mem_init()
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:48 +0000 (15:03 -0700)]
mm/ARM: prepare for removing num_physpages and simplify mem_init()
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Russell King <linux@arm.linux.org.uk> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:45 +0000 (15:03 -0700)]
mm/alpha: prepare for removing num_physpages and simplify mem_init()
Prepare for removing num_physpages and simplify mem_init().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Matt Turner <mattst88@gmail.com> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:41 +0000 (15:03 -0700)]
mm: introduce helper function mem_init_print_info() to simplify mem_init()
Introduce helper function mem_init_print_info() to simplify mem_init()
across different architectures, which also unifies the format and
information printed.
Function mem_init_print_info() calculates memory statistics information
without walking each page, so it should be a little faster on some
architectures.
Also introduce another helper get_num_physpages() to kill the global
variable num_physpages.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:40 +0000 (15:03 -0700)]
UML: normalize global variables exported by vmlinux.lds
Normalize global variables exported by vmlinux.lds to conform usage
guidelines from include/asm-generic/sections.h.
1) Use _text to mark the start of the kernel image including the head
text, and _stext to mark the start of the .text section.
2) Export mandatory global variables __bss_stop.
3) Adjust __init_begin and __init_end to avoid acrossing .text and
.data sections.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Jeff Dike <jdike@addtoit.com> Cc: Richard Weinberger <richard@nod.at> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:39 +0000 (15:03 -0700)]
tile: normalize global variables exported by vmlinux.lds
Normalize global variables exported by vmlinux.lds to conform usage
guidelines from include/asm-generic/sections.h.
1) Use _text to mark the start of the kernel image including the head
text, and _stext to mark the start of the .text section.
2) Export mandatory global variables __init_begin and __init_end.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Acked-by: Chris Metcalf <cmetcalf@tilera.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Bjorn Helgaas <bhelgaas@google.com> Cc: "David S. Miller" <davem@davemloft.net> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:36 +0000 (15:03 -0700)]
h8300: normalize global variables exported by vmlinux.lds
Generate mandatory global variables __bss_start/__bss_stop in
file vmlinux.lds.
Also remove one unused declaration of _text.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Cc: Jiang Liu <jiang.liu@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:35 +0000 (15:03 -0700)]
c6x: normalize global variables exported by vmlinux.lds
Normalize global variables exported by vmlinux.lds to conform usage
guidelines from include/asm-generic/sections.h.
Use _text to mark the start of the kernel image including the head text,
and _stext to mark the start of the .text section.
This patch also fixes possible bugs due to current address layout that
[__init_begin, __init_end] is a sub-range of [_stext, _etext] and pages
within range [__init_begin, __init_end] will be freed by free_initmem().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Mark Salter <msalter@redhat.com> Cc: Aurelien Jacquiot <a-jacquiot@ti.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:33 +0000 (15:03 -0700)]
vmlinux.lds: add comments for global variables and clean up useless declarations
The original goal of this patchset is to fix the bug reported by
https://bugzilla.kernel.org/show_bug.cgi?id=53501 Now it has also been
expanded to reduce common code used by memory initializion.
Patch 1-7:
1) add comments for global variables exported by vmlinux.lds
2) normalize global variables exported by vmlinux.lds
Patch 8:
Introduce helper functions mem_init_print_info() and
get_num_physpages()
Patch 9:
Avoid using global variable num_physpages at runtime
Patch 10:
Don't update num_physpages in memory_hotplug.c
Patch 11-40:
Modify arch mm initialization code to:
1) Simplify mem_init() by using mem_init_print_info()
2) Prepare for killing global variable num_physpages
Patch 41:
Kill the global variable num_physpages
With all patches applied, mem_init(), free_initmem(), free_initrd_mem()
could be as simple as below. This patch series has reduced about 1.2K
lines of code in total.
mm: fix the TLB range flushed when __tlb_remove_page() runs out of slots
zap_pte_range loops from @addr to @end. In the middle, if it runs out of
batching slots, TLB entries needs to be flushed for @start to @interim,
NOT @interim to @end.
Since ARC port doesn't use page free batching I can't test it myself but
this seems like the right thing to do.
Observed this when working on a fix for the issue at thread:
http://www.spinics.net/lists/linux-arch/msg21736.html
Signed-off-by: Vineet Gupta <vgupta@synopsys.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: David Rientjes <rientjes@google.com> Cc: Peter Zijlstra <peterz@infradead.org> Acked-by: Catalin Marinas <catalin.marinas@arm.com> Cc: Max Filippov <jcmvbkbc@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:27 +0000 (15:03 -0700)]
mm: report available pages as "MemTotal" for each NUMA node
As reported by https://bugzilla.kernel.org/show_bug.cgi?id=53501,
"MemTotal" from /proc/meminfo means memory pages managed by the buddy
system (managed_pages), but "MemTotal" from /sys/.../node/nodex/meminfo
means physical pages present (present_pages) within the NUMA node.
There's a difference between managed_pages and present_pages due to
bootmem allocator and reserved pages.
And Documentation/filesystems/proc.txt says
MemTotal: Total usable ram (i.e. physical ram minus a few reserved
bits and the kernel binary code)
So change /sys/.../node/nodex/meminfo to report available pages within
the node as "MemTotal".
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Reported-by: <sworddragon2@aol.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:24 +0000 (15:03 -0700)]
mm: concentrate modification of totalram_pages into the mm core
Concentrate code to modify totalram_pages into the mm core, so the arch
memory initialized code doesn't need to take care of it. With these
changes applied, only following functions from mm core modify global
variable totalram_pages: free_bootmem_late(), free_all_bootmem(),
free_all_bootmem_node(), adjust_managed_page_count().
With this patch applied, it will be much more easier for us to keep
totalram_pages and zone->managed_pages in consistence.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Acked-by: David Howells <dhowells@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: <sworddragon2@aol.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michel Lespinasse <walken@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:21 +0000 (15:03 -0700)]
mm: correctly update zone->managed_pages
Enhance adjust_managed_page_count() to adjust totalhigh_pages for
highmem pages. And change code which directly adjusts totalram_pages to
use adjust_managed_page_count() because it adjusts totalram_pages,
totalhigh_pages and zone->managed_pages altogether in a safe way.
Remove inc_totalhigh_pages() and dec_totalhigh_pages() from xen/balloon
driver bacause adjust_managed_page_count() has already adjusted
totalhigh_pages.
This patch also fixes two bugs:
1) enhances virtio_balloon driver to adjust totalhigh_pages when
reserve/unreserve pages.
2) enhance memory_hotplug.c to adjust totalhigh_pages when hot-removing
memory.
We still need to deal with modifications of totalram_pages in file
arch/powerpc/platforms/pseries/cmm.c, but need help from PPC experts.
[akpm@linux-foundation.org: remove ifdef, per Wanpeng Li, virtio_balloon.c cleanup, per Sergei]
[akpm@linux-foundation.org: export adjust_managed_page_count() to modules, for drivers/virtio/virtio_balloon.c] Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: <sworddragon2@aol.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: David Howells <dhowells@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:17 +0000 (15:03 -0700)]
mm: make __free_pages_bootmem() only available at boot time
In order to simpilify management of totalram_pages and
zone->managed_pages, make __free_pages_bootmem() only available at boot
time. With this change applied, __free_pages_bootmem() will only be
used by bootmem.c and nobootmem.c at boot time, so mark it as __init.
Other callers of __free_pages_bootmem() have been converted to use
free_reserved_page(), which handles totalram_pages and
zone->managed_pages in a safer way.
This patch also fix a bug in free_pagetable() for x86_64, which should
increase zone->managed_pages instead of zone->present_pages when freeing
reserved pages.
And now we have managed_pages_count_lock to protect totalram_pages and
zone->managed_pages, so remove the redundant ppb_lock lock in
put_page_bootmem(). This greatly simplifies the locking rules.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Ingo Molnar <mingo@redhat.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan@kernel.org> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: <sworddragon2@aol.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tejun Heo <tj@kernel.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:14 +0000 (15:03 -0700)]
mm: use a dedicated lock to protect totalram_pages and zone->managed_pages
Currently lock_memory_hotplug()/unlock_memory_hotplug() are used to
protect totalram_pages and zone->managed_pages. Other than the memory
hotplug driver, totalram_pages and zone->managed_pages may also be
modified at runtime by other drivers, such as Xen balloon,
virtio_balloon etc. For those cases, memory hotplug lock is a little
too heavy, so introduce a dedicated lock to protect totalram_pages and
zone->managed_pages.
Now we have a simplified locking rules totalram_pages and
zone->managed_pages as:
1) no locking for read accesses because they are unsigned long.
2) no locking for write accesses at boot time in single-threaded context.
3) serialize write accesses at runtime by acquiring the dedicated
managed_page_count_lock.
Also adjust zone->managed_pages when freeing reserved pages into the
buddy system, to keep totalram_pages and zone->managed_pages in
consistence.
[akpm@linux-foundation.org: don't export adjust_managed_page_count to modules (for now)] Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: <sworddragon2@aol.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:03:11 +0000 (15:03 -0700)]
mm: accurately calculate zone->managed_pages for highmem zones
Commit "mm: introduce new field 'managed_pages' to struct zone" assumes
that all highmem pages will be freed into the buddy system by function
mem_init(). But that's not always true, some architectures may reserve
some highmem pages during boot. For example PPC may allocate highmem
pages for giagant HugeTLB pages, and several architectures have code to
check PageReserved flag to exclude highmem pages allocated during boot
when freeing highmem pages into the buddy system.
So treat highmem pages in the same way as normal pages, that is to:
1) reset zone->managed_pages to zero in mem_init().
2) recalculate managed_pages when freeing pages into the buddy system.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Tejun Heo <tj@kernel.org> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Minchan Kim <minchan@kernel.org> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: <sworddragon2@aol.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:02:51 +0000 (15:02 -0700)]
mm: enhance free_reserved_area() to support poisoning memory with zero
Address more review comments from last round of code review.
1) Enhance free_reserved_area() to support poisoning freed memory with
pattern '0'. This could be used to get rid of poison_init_mem()
on ARM64.
2) A previous patch has disabled memory poison for initmem on s390
by mistake, so restore to the original behavior.
3) Remove redundant PAGE_ALIGN() when calling free_reserved_area().
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: <sworddragon2@aol.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michel Lespinasse <walken@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiang Liu [Wed, 3 Jul 2013 22:02:48 +0000 (15:02 -0700)]
mm: change signature of free_reserved_area() to fix building warnings
Change signature of free_reserved_area() according to Russell King's
suggestion to fix following build warnings:
arch/arm/mm/init.c: In function 'mem_init':
arch/arm/mm/init.c:603:2: warning: passing argument 1 of 'free_reserved_area' makes integer from pointer without a cast [enabled by default]
free_reserved_area(__va(PHYS_PFN_OFFSET), swapper_pg_dir, 0, NULL);
^
In file included from include/linux/mman.h:4:0,
from arch/arm/mm/init.c:15:
include/linux/mm.h:1301:22: note: expected 'long unsigned int' but argument is of type 'void *'
extern unsigned long free_reserved_area(unsigned long start, unsigned long end,
mm/page_alloc.c: In function 'free_reserved_area':
>> mm/page_alloc.c:5134:3: warning: passing argument 1 of 'virt_to_phys' makes pointer from integer without a cast [enabled by default]
In file included from arch/mips/include/asm/page.h:49:0,
from include/linux/mmzone.h:20,
from include/linux/gfp.h:4,
from include/linux/mm.h:8,
from mm/page_alloc.c:18:
arch/mips/include/asm/io.h:119:29: note: expected 'const volatile void *' but argument is of type 'long unsigned int'
mm/page_alloc.c: In function 'free_area_init_nodes':
mm/page_alloc.c:5030:34: warning: array subscript is below array bounds [-Warray-bounds]
Also address some minor code review comments.
Signed-off-by: Jiang Liu <jiang.liu@huawei.com> Reported-by: Arnd Bergmann <arnd@arndb.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: "Michael S. Tsirkin" <mst@redhat.com> Cc: <sworddragon2@aol.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: David Howells <dhowells@redhat.com> Cc: Geert Uytterhoeven <geert@linux-m68k.org> Cc: Ingo Molnar <mingo@redhat.com> Cc: Jeremy Fitzhardinge <jeremy@goop.org> Cc: Jianguo Wu <wujianguo@huawei.com> Cc: Joonsoo Kim <js1304@gmail.com> Cc: Kamezawa Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Marek Szyprowski <m.szyprowski@samsung.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Michel Lespinasse <walken@google.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Rusty Russell <rusty@rustcorp.com.au> Cc: Tang Chen <tangchen@cn.fujitsu.com> Cc: Tejun Heo <tj@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Wen Congyang <wency@cn.fujitsu.com> Cc: Will Deacon <will.deacon@arm.com> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com> Cc: Yinghai Lu <yinghai@kernel.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rafael Aquini [Wed, 3 Jul 2013 22:02:46 +0000 (15:02 -0700)]
swap: discard while swapping only if SWAP_FLAG_DISCARD_PAGES
Considering the use cases where the swap device supports discard:
a) and can do it quickly;
b) but it's slow to do in small granularities (or concurrent with other
I/O);
c) but the implementation is so horrendous that you don't even want to
send one down;
And assuming that the sysadmin considers it useful to send the discards down
at all, we would (probably) want the following solutions:
i. do the fine-grained discards for freed swap pages, if device is
capable of doing so optimally;
ii. do single-time (batched) swap area discards, either at swapon
or via something like fstrim (not implemented yet);
iii. allow doing both single-time and fine-grained discards; or
iv. turn it off completely (default behavior)
As implemented today, one can only enable/disable discards for swap, but
one cannot select, for instance, solution (ii) on a swap device like (b)
even though the single-time discard is regarded to be interesting, or
necessary to the workload because it would imply (1), and the device is
not capable of performing it optimally.
This patch addresses the scenario depicted above by introducing a way to
ensure the (probably) wanted solutions (i, ii, iii and iv) can be flexibly
flagged through swapon(8) to allow a sysadmin to select the best suitable
swap discard policy accordingly to system constraints.
This patch introduces SWAP_FLAG_DISCARD_PAGES and SWAP_FLAG_DISCARD_ONCE
new flags to allow more flexibe swap discard policies being flagged
through swapon(8). The default behavior is to keep both single-time, or
batched, area discards (SWAP_FLAG_DISCARD_ONCE) and fine-grained discards
for page-clusters (SWAP_FLAG_DISCARD_PAGES) enabled, in order to keep
consistentcy with older kernel behavior, as well as maintain compatibility
with older swapon(8). However, through the new introduced flags the best
suitable discard policy can be selected accordingly to any given swap
device constraint.
[akpm@linux-foundation.org: tweak comments] Signed-off-by: Rafael Aquini <aquini@redhat.com> Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Hugh Dickins <hughd@google.com> Cc: Shaohua Li <shli@kernel.org> Cc: Karel Zak <kzak@redhat.com> Cc: Jeff Moyer <jmoyer@redhat.com> Cc: Rik van Riel <riel@redhat.com> Cc: Larry Woodman <lwoodman@redhat.com> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the per cpu counter's batch size for memory accounting is
configured as twice the number of cpus in the system. However, for
system with very large memory, it is more appropriate to make it
proportional to the memory size per cpu in the system.
For example, for a x86_64 system with 64 cpus and 128 GB of memory, the
batch size is only 2*64 pages (0.5 MB). So any memory accounting
changes of more than 0.5MB will overflow the per cpu counter into the
global counter. Instead, for the new scheme, the batch size is
configured to be 0.4% of the memory/cpu = 8MB (128 GB/64 /256), which is
more inline with the memory size.
I've done a repeated brk test of 800KB (from will-it-scale test suite)
with 80 concurrent processes on a 4 socket Westmere machine with a total
of 40 cores. Without the patch, about 80% of cpu is spent on spin-lock
contention within the vm_committed_as counter. With the patch, there's
a 73x speedup on the benchmark and the lock contention drops off almost
entirely.
[akpm@linux-foundation.org: fix section mismatch] Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com> Cc: Tejun Heo <tj@kernel.org> Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Wanpeng Li [Wed, 3 Jul 2013 22:02:40 +0000 (15:02 -0700)]
mm/memory-hotplug: fix lowmem count overflow when offline pages
The logic for the memory-remove code fails to correctly account the
Total High Memory when a memory block which contains High Memory is
offlined as shown in the example below. The following patch fixes it.
mm/memory_hotplug.c: change normal message to use pr_debug
During early boot-up, iomem_resource is set up from the boot descriptor
table, such as EFI Memory Table and e820. Later,
acpi_memory_device_add() calls add_memory() for each ACPI memory device
object as it enumerates ACPI namespace. This add_memory() call is
expected to fail in register_memory_resource() at boot since
iomem_resource has been set up from EFI/e820. As a result, add_memory()
returns -EEXIST, which acpi_memory_device_add() handles as the normal
case.
This scheme works fine, but the following error message is logged for
every ACPI memory device object during boot-up.
"System RAM resource %pR cannot be added\n"
This patch changes register_memory_resource() to use pr_debug() for the
message as it shows up under the normal case.
mm/memory-failure.c: fix memory leak in successful soft offlining
After a successful page migration by soft offlining, the source page is
not properly freed and it's never reusable even if we unpoison it
afterward.
This is caused by the race between freeing page and setting PG_hwpoison.
In successful soft offlining, the source page is put (and the refcount
becomes 0) by putback_lru_page() in unmap_and_move(), where it's linked
to pagevec and actual freeing back to buddy is delayed. So if
PG_hwpoison is set for the page before freeing, the freeing does not
functions as expected (in such case freeing aborts in
free_pages_prepare() check.)
This patch tries to make sure to free the source page before setting
PG_hwpoison on it. To avoid reallocating, the page keeps
MIGRATE_ISOLATE until after setting PG_hwpoison.
This patch also removes obsolete comments about "keeping elevated
refcount" because what they say is not true. Unlike memory_failure(),
soft_offline_page() uses no special page isolation code, and the
soft-offlined pages have no elevated.
Chen Gang [Wed, 3 Jul 2013 22:02:36 +0000 (15:02 -0700)]
mm/nommu.c: add additional check for vread() just like vwrite() has done
vwrite() checks for overflow. vread() should do the same thing.
Since vwrite() checks the source buffer address, vread() should check
the destination buffer address.
Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Michel Lespinasse <walken@google.com> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: remove lru parameter from __lru_cache_add and lru_cache_add_lru
Similar to __pagevec_lru_add, this patch removes the LRU parameter from
__lru_cache_add and lru_cache_add_lru as the caller does not control the
exact LRU the page gets added to. lru_cache_add_lru gets renamed to
lru_cache_add the name is silly without the lru parameter. With the
parameter removed, it is required that the caller indicate if they want
the page added to the active or inactive list by setting or clearing
PageActive respectively.
[akpm@linux-foundation.org: Suggested the patch]
[gang.chen@asianux.com: fix used-unintialized warning] Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Chen Gang <gang.chen@asianux.com> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com> Cc: Andrew Perepechko <anserper@ya.ru> Cc: Robin Dong <sanbai@taobao.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Bernd Schubert <bernd.schubert@fastmail.fm> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Rik van Riel <riel@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: remove lru parameter from __pagevec_lru_add and remove parts of pagevec API
Now that the LRU to add a page to is decided at LRU-add time, remove the
misleading lru parameter from __pagevec_lru_add. A consequence of this
is that the pagevec_lru_add_file, pagevec_lru_add_anon and similar
helpers are misleading as the caller no longer has direct control over
what LRU the page is added to. Unused helpers are removed by this patch
and existing users of pagevec_lru_add_file() are converted to use
lru_cache_add_file() directly and use the per-cpu pagevecs instead of
creating their own pagevec.
Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com> Cc: Andrew Perepechko <anserper@ya.ru> Cc: Robin Dong <sanbai@taobao.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Bernd Schubert <bernd.schubert@fastmail.fm> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: activate !PageLRU pages on mark_page_accessed if page is on local pagevec
If a page is on a pagevec then it is !PageLRU and mark_page_accessed()
may fail to move a page to the active list as expected. Now that the
LRU is selected at LRU drain time, mark pages PageActive if they are on
the local pagevec so it gets moved to the correct list at LRU drain
time. Using a debugging patch it was found that for a simple git
checkout based workload that pages were never added to the active file
list in practice but with this patch applied they are.
before after
LRU Add Active File 0 750583
LRU Add Active Anon 26405872702818
LRU Add Inactive File 88336628068353
LRU Add Inactive Anon 207 200
Note that only pages on the local pagevec are considered on purpose. A
!PageLRU page could be in the process of being released, reclaimed,
migrated or on a remote pagevec that is currently being drained.
Marking it PageActive is vunerable to races where PageLRU and Active
bits are checked at the wrong time. Page reclaim will trigger
VM_BUG_ONs but depending on when the race hits, it could also free a
PageActive page to the page allocator and trigger a bad_page warning.
Similarly a potential race exists between a per-cpu drain on a pagevec
list and an activation on a remote CPU.
In this case a PageActive page is added to the inactivate list and later
the inactive/active stats will get skewed. While the PageActive checks
in vmscan could be removed and potentially dealt with, a skew in the
statistics would be very difficult to detect. Hence this patch deals
just with the common case where a page being marked accessed has just
been added to the local pagevec.
Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Jan Kara <jack@suse.cz> Cc: Rik van Riel <riel@redhat.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com> Cc: Andrew Perepechko <anserper@ya.ru> Cc: Robin Dong <sanbai@taobao.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Bernd Schubert <bernd.schubert@fastmail.fm> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: pagevec: defer deciding which LRU to add a page to until pagevec drain time
mark_page_accessed() cannot activate an inactive page that is located on
an inactive LRU pagevec. Hints from filesystems may be ignored as a
result. In preparation for fixing that problem, this patch removes the
per-LRU pagevecs and leaves just one pagevec. The final LRU the page is
added to is deferred until the pagevec is drained.
This means that fewer pagevecs are available and potentially there is
greater contention on the LRU lock. However, this only applies in the
case where there is an almost perfect mix of file, anon, active and
inactive pages being added to the LRU. In practice I expect that we are
adding stream of pages of a particular time and that the changes in
contention will barely be measurable.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Cc: Jan Kara <jack@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com> Cc: Andrew Perepechko <anserper@ya.ru> Cc: Robin Dong <sanbai@taobao.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Bernd Schubert <bernd.schubert@fastmail.fm> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: add tracepoints for LRU activation and insertions
Andrew Perepechko reported a problem whereby pages are being prematurely
evicted as the mark_page_accessed() hint is ignored for pages that are
currently on a pagevec --
http://www.spinics.net/lists/linux-ext4/msg37340.html .
Alexey Lyahkov and Robin Dong have also reported problems recently that
could be due to hot pages reaching the end of the inactive list too
quickly and be reclaimed.
Rather than addressing this on a per-filesystem basis, this series aims
to fix the mark_page_accessed() interface by deferring what LRU a page
is added to pagevec drain time and allowing mark_page_accessed() to call
SetPageActive on a pagevec page.
Patch 1 adds two tracepoints for LRU page activation and insertion. Using
these processes it's possible to build a model of pages in the
LRU that can be processed offline.
Patch 2 defers making the decision on what LRU to add a page to until when
the pagevec is drained.
Patch 3 searches the local pagevec for pages to mark PageActive on
mark_page_accessed. The changelog explains why only the local
pagevec is examined.
Patches 4 and 5 tidy up the API.
postmark, a dd-based test and fs-mark both single and threaded mode were
run but none of them showed any performance degradation or gain as a
result of the patch.
Using patch 1, I built a *very* basic model of the LRU to examine
offline what the average age of different page types on the LRU were in
milliseconds. Of course, capturing the trace distorts the test as it's
written to local disk but it does not matter for the purposes of this
test. The average age of pages in milliseconds were
vanilla deferdrain
Average age mapped anon: 1454 1250
Average age mapped file: 127841 155552
Average age unmapped anon: 85 235
Average age unmapped file: 73633 38884
Average age unmapped buffers: 74054 116155
The LRU activity was mostly files which you'd expect for a dd-based
workload. Note that the average age of buffer pages is increased by the
series and it is expected this is due to the fact that the buffer pages
are now getting added to the active list when drained from the pagevecs.
Note that the average age of the unmapped file data is decreased as they
are still added to the inactive list and are reclaimed before the
buffers.
There is no guarantee this is a universal win for all workloads and it
would be nice if the filesystem people gave some thought as to whether
this decision is generally a win or a loss.
This patch:
Using these tracepoints it is possible to model LRU activity and the
average residency of pages of different types. This can be used to
debug problems related to premature reclaim of pages of particular
types.
Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Jan Kara <jack@suse.cz> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Alexey Lyahkov <alexey.lyashkov@gmail.com> Cc: Andrew Perepechko <anserper@ya.ru> Cc: Robin Dong <sanbai@taobao.com> Cc: Theodore Tso <tytso@mit.edu> Cc: Hugh Dickins <hughd@google.com> Cc: Rik van Riel <riel@redhat.com> Cc: Bernd Schubert <bernd.schubert@fastmail.fm> Cc: David Howells <dhowells@redhat.com> Cc: Trond Myklebust <Trond.Myklebust@netapp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Don't permit writable nor executable mapping even with mprotect()
because this mmap() is aimed at reading crash dump memory. Non-writable
mapping is also requirement of remap_pfn_range() when mapping linear
pages on non-consecutive physical pages; see is_cow_mapping().
Set VM_MIXEDMAP flag to remap memory by remap_pfn_range and by
remap_vmalloc_range_pertial at the same time for a single vma.
do_munmap() can correctly clean partially remapped vma with two
functions in abnormal case. See zap_pte_range(), vm_normal_page() and
their comments for details.
On x86-32 PAE kernels, mmap() supports at most 16TB memory only. This
limitation comes from the fact that the third argument of
remap_pfn_range(), pfn, is of 32-bit length on x86-32: unsigned long.
vmcore: calculate vmcore file size from buffer size and total size of vmcore objects
The previous patches newly added holes before each chunk of memory and
the holes need to be count in vmcore file size. There are two ways to
count file size in such a way:
1) suppose m is a poitner to the last vmcore object in vmcore_list.
Then file size is (m->offset + m->size), or
2) calculate sum of size of buffers for ELF header, program headers,
ELF note segments and objects in vmcore_list.
Although 1) is more direct and simpler than 2), 2) seems better in that
it reflects internal object structure of /proc/vmcore. Thus, this patch
changes get_vmcore_size_elf{64, 32} so that it calculates size in the
way of 2).
As a result, both get_vmcore_size_elf{64, 32} have the same definition.
Merge them as get_vmcore_size.
vmcore: allow user process to remap ELF note segment buffer
Now ELF note segment has been copied in the buffer on vmalloc memory.
To allow user process to remap the ELF note segment buffer with
remap_vmalloc_page, the corresponding VM area object has to have
VM_USERMAP flag set.
[akpm@linux-foundation.org: use the conventional comment layout] Signed-off-by: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com> Acked-by: Vivek Goyal <vgoyal@redhat.com> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp> Cc: Lisa Mitchell <lisa.mitchell@hp.com> Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vmcore: allocate ELF note segment in the 2nd kernel vmalloc memory
The reasons why we don't allocate ELF note segment in the 1st kernel
(old memory) on page boundary is to keep backward compatibility for old
kernels, and that if doing so, we waste not a little memory due to
round-up operation to fit the memory to page boundary since most of the
buffers are in per-cpu area.
ELF notes are per-cpu, so total size of ELF note segments depends on
number of CPUs. The current maximum number of CPUs on x86_64 is 5192,
and there's already system with 4192 CPUs in SGI, where total size
amounts to 1MB. This can be larger in the near future or possibly even
now on another architecture that has larger size of note per a single
cpu. Thus, to avoid the case where memory allocation for large block
fails, we allocate vmcore objects on vmalloc memory.
This patch adds elfnotes_buf and elfnotes_sz variables to keep pointer
to the ELF note segment buffer and its size. There's no longer the
vmcore object that corresponds to the ELF note segment in vmcore_list.
Accordingly, read_vmcore() has new case for ELF note segment and
set_vmcore_list_offsets_elf{64,32}() and other helper functions starts
calculating offset from sum of size of ELF headers and size of ELF note
segment.
We want to allocate ELF note segment buffer on the 2nd kernel in vmalloc
space and remap it to user-space in order to reduce the risk that memory
allocation fails on system with huge number of CPUs and so with huge ELF
note segment that exceeds 11-order block size.
Although there's already remap_vmalloc_range for the purpose of
remapping vmalloc memory to user-space, we need to specify user-space
range via vma.
Mmap on /proc/vmcore needs to remap range across multiple objects, so
the interface that requires vma to cover full range is problematic.
This patch introduces remap_vmalloc_range_partial that receives user-space
range as a pair of base address and size and can be used for mmap on
/proc/vmcore case.
remap_vmalloc_range is rewritten using remap_vmalloc_range_partial.
Currently, __find_vmap_area searches for the kernel VM area starting at
a given address. This patch changes this behavior so that it searches
for the kernel VM area to which the address belongs. This change is
needed by remap_vmalloc_range_partial to be introduced in later patch
that receives any position of kernel VM area as target address.
This patch changes the condition (addr > va->va_start) to the equivalent
(addr >= va->va_end) by taking advantage of the fact that each kernel VM
area is non-overlapping.
vmcore: treat memory chunks referenced by PT_LOAD program header entries in page-size boundary in vmcore_list
Treat memory chunks referenced by PT_LOAD program header entries in
page-size boundary in vmcore_list. Formally, for each range [start,
end], we set up the corresponding vmcore object in vmcore_list to
[rounddown(start, PAGE_SIZE), roundup(end, PAGE_SIZE)].
This change affects layout of /proc/vmcore. The gaps generated by the
rearrangement are newly made visible to applications as holes.
Concretely, they are two ranges [rounddown(start, PAGE_SIZE), start] and
[end, roundup(end, PAGE_SIZE)].
Suppose variable m points at a vmcore object in vmcore_list, and
variable phdr points at the program header of PT_LOAD type the variable
m corresponds to. Then, pictorially:
vmcore: allocate buffer for ELF headers on page-size alignment
Allocate ELF headers on page-size boundary using __get_free_pages()
instead of kmalloc().
Later patch will merge PT_NOTE entries into a single unique one and
decrease the buffer size actually used. Keep original buffer size in
variable elfcorebuf_sz_orig to kfree the buffer later and actually used
buffer size with rounded up to page-size boundary in variable
elfcorebuf_sz separately.
The size of part of the ELF buffer exported from /proc/vmcore is
elfcorebuf_sz.
The merged, removed PT_NOTE entries, i.e. the range [elfcorebuf_sz,
elfcorebuf_sz_orig], is filled with 0.
Use size of the ELF headers as an initial offset value in
set_vmcore_list_offsets_elf{64,32} and
process_ptload_program_headers_elf{64,32} in order to indicate that the
offset includes the holes towards the page boundary.
As a result, both set_vmcore_list_offsets_elf{64,32} have the same
definition. Merge them as set_vmcore_list_offsets.
Rewrite part of read_vmcore() that reads objects in vmcore_list in the
same way as part reading ELF headers, by which some duplicated and
redundant codes are removed.
fs: nfs: inform the VM about pages being committed or unstable
VM page reclaim uses dirty and writeback page states to determine if
flushers are cleaning pages too slowly and that page reclaim should
stall waiting on flushers to catch up. Page state in NFS is a bit more
complex and a clean page can be unreclaimable due to being unstable
which is effectively "dirty" from the perspective of the VM from reclaim
context. Similarly, if the inode is currently being committed then it's
similar to being under writeback.
This patch adds a is_dirty_writeback() handled for NFS that checks if a
pages backing inode is being committed and should be accounted as
writeback and if a page has private state indicating that it is
effectively dirty.
mm: vmscan: take page buffers dirty and locked state into account
Page reclaim keeps track of dirty and under writeback pages and uses it
to determine if wait_iff_congested() should stall or if kswapd should
begin writing back pages. This fails to account for buffer pages that
can be under writeback but not PageWriteback which is the case for
filesystems like ext3 ordered mode. Furthermore, PageDirty buffer pages
can have all the buffers clean and writepage does no IO so it should not
be accounted as congested.
This patch adds an address_space operation that filesystems may
optionally use to check if a page is really dirty or really under
writeback. An implementation is provided for for buffer_heads is added
and used for block operations and ext3 in ordered mode. By default the
page flags are obeyed.
Credit goes to Jan Kara for identifying that the page flags alone are
not sufficient for ext3 and sanity checking a number of ideas on how the
problem could be addressed.
mm: vmscan: treat pages marked for immediate reclaim as zone congestion
Currently a zone will only be marked congested if the underlying BDI is
congested but if dirty pages are spread across zones it is possible that
an individual zone is full of dirty pages without being congested. The
impact is that zone gets scanned very quickly potentially reclaiming
really clean pages. This patch treats pages marked for immediate
reclaim as congested for the purposes of marking a zone ZONE_CONGESTED
and stalling in wait_iff_congested.
mm: vmscan: move direct reclaim wait_iff_congested into shrink_list
shrink_inactive_list makes decisions on whether to stall based on the
number of dirty pages encountered. The wait_iff_congested() call in
shrink_page_list does no such thing and it's arbitrary.
This patch moves the decision on whether to set ZONE_CONGESTED and the
wait_iff_congested call into shrink_page_list. This keeps all the
decisions on whether to stall or not in the one place.
In shrink_page_list a decision may be made to stall and flag a zone as
ZONE_WRITEBACK so that if a large number of unqueued dirty pages are
encountered later then the reclaimer will stall. Set ZONE_WRITEBACK
before potentially going to sleep so it is noticed sooner.
mm: vmscan: stall page reclaim after a list of pages have been processed
Commit "mm: vmscan: Block kswapd if it is encountering pages under
writeback" blocks page reclaim if it encounters pages under writeback
marked for immediate reclaim. It blocks while pages are still isolated
from the LRU which is unnecessary. This patch defers the blocking until
after the isolated pages have been processed and tidies up some of the
comments.
mm: vmscan: stall page reclaim and writeback pages based on dirty/writepage pages encountered
Further testing of the "Reduce system disruption due to kswapd"
discovered a few problems. First and foremost, it's possible for pages
under writeback to be freed which will lead to badness. Second, as
pages were not being swapped the file LRU was being scanned faster and
clean file pages were being reclaimed. In some cases this results in
increased read IO to re-read data from disk. Third, more pages were
being written from kswapd context which can adversly affect IO
performance. Lastly, it was observed that PageDirty pages are not
necessarily dirty on all filesystems (buffers can be clean while
PageDirty is set and ->writepage generates no IO) and not all
filesystems set PageWriteback when the page is being written (e.g.
ext3). This disconnect confuses the reclaim stalling logic. This
follow-up series is aimed at these problems.
The tests were based on three kernels
vanilla: kernel 3.9 as that is what the current mmotm uses as a baseline
mmotm-20130522 is mmotm as of 22nd May with "Reduce system disruption due to
kswapd" applied on top as per what should be in Andrew's tree
right now
lessdisrupt-v7r10 is this follow-up series on top of the mmotm kernel
The first test used memcached+memcachetest while some background IO was
in progress as implemented by the parallel IO tests implement in MM
Tests. memcachetest benchmarks how many operations/second memcached can
service. It starts with no background IO on a freshly created ext4
filesystem and then re-runs the test with larger amounts of IO in the
background to roughly simulate a large copy in progress. The
expectation is that the IO should have little or no impact on
memcachetest which is running entirely in memory.
memcachetest is the transactions/second reported by memcachetest. In
the vanilla kernel note that performance drops from around
23K/sec to just over 4K/second when there is 2385M of IO going
on in the background. With current mmotm, there is no collapse
in performance and with this follow-up series there is little
change.
swaptotal is the total amount of swap traffic. With mmotm and the follow-up
series, the total amount of swapping is much reduced.
1. Swap outs are almost eliminated. Swap ins are 0 indicating that the
pages swapped were really unused anonymous pages. Related to that,
major faults are much reduced.
2. kswapd efficiency was impacted by the initial series but with these
follow-up patches, the efficiency is now at 66% indicating that far
fewer pages were skipped during scanning due to dirty or writeback
pages.
3. kswapd velocity is reduced indicating that fewer pages are being scanned
with the follow-up series as kswapd now stalls when the tail of the
LRU queue is full of unqueued dirty pages. The stall gives flushers a
chance to catch-up so kswapd can reclaim clean pages when it wakes
4. In light of Zlatko's recent reports about zone scanning imbalances,
mmtests now reports scanning velocity on a per-zone basis. With mainline,
you can see that the scanning activity is dominated by the Normal
zone with over 45 times more scanning in Normal than the DMA32 zone.
With the series currently in mmotm, the ratio is slightly better but it
is still the case that the bulk of scanning is in the highest zone. With
this follow-up series, the ratio of scanning between the Normal and
DMA32 zone is roughly equal.
5. As Dave Chinner observed, the current patches in mmotm increased the
number of pages written from kswapd context which is expected to adversly
impact IO performance. With the follow-up patches, far fewer pages are
written from kswapd context than the mainline kernel
6. With the series in mmotm, fewer inodes were reclaimed by kswapd. With
the follow-up series, there is less slab shrinking activity and no inodes
were reclaimed.
7. Note that "Sectors Read" is drastically reduced implying that the source
data being used for the IO is not being aggressively discarded due to
page reclaim skipping over dirty pages and reclaiming clean pages. Note
that the reducion in reads could also be due to inode data not being
re-read from disk after a slab shrink.
3.9.0 3.9.0 3.9.0
vanillamm1-mmotm-20130522mm1-lessdisrupt-v7r10
Mean sda-avgqz 166.99 32.09 33.44
Mean sda-await 853.64 192.76 185.43
Mean sda-r_await 6.31 9.24 5.97
Mean sda-w_await 2992.81 202.65 192.43
Max sda-avgqz 1409.91 718.75 698.98
Max sda-await 6665.74 3538.00 3124.23
Max sda-r_await 58.96 111.95 58.00
Max sda-w_await 28458.94 3977.29 3148.61
In light of the changes in writes from reclaim context, the number of
reads and Dave Chinner's concerns about IO performance I took a closer
look at the IO stats for the test disk. Few observations
1. The average queue size is reduced by the initial series and roughly
the same with this follow up.
2. Average wait times for writes are reduced and as the IO
is completing faster it at least implies that the gain is because
flushers are writing the files efficiently instead of page reclaim
getting in the way.
3. The reduction in maximum write latency is staggering. 28 seconds down
to 3 seconds.
Jan Kara asked how NFS is affected by all of this. Unstable pages can
be taken into account as one of the patches in the series shows but it
is still the case that filesystems with unusual handling of dirty or
writeback could still be treated better.
Tests like postmark, fsmark and largedd showed up nothing useful. On my test
setup, pages are simply not being written back from reclaim context with or
without the patches and there are no changes in performance. My test setup
probably is just not strong enough network-wise to be really interesting.
I ran a longer-lived memcached test with IO going to NFS instead of a local disk
1. Performance does not collapse due to IO which is good. IO is also completing
faster. Note with mmotm, IO completes in a third of the time and faster again
with this series applied
2. Swapping is reduced, although not eliminated. The figures for the follow-up
look bad but it does vary a bit as the stalling is not perfect for nfs
or filesystems like ext3 with unusual handling of dirty and writeback
pages
3. There are swapins, particularly with larger amounts of IO indicating
that active pages are being reclaimed. However, the number of much
reduced.
I guess the main takeaway again is the much reduced page writes
from reclaim context and reduced reads.
3.9.0 3.9.0 3.9.0
vanillamm1-mmotm-20130522mm1-lessdisrupt-v7r10
Mean sda-avgqz 23.58 0.35 0.44
Mean sda-await 133.47 15.72 15.46
Mean sda-r_await 4.72 4.69 3.95
Mean sda-w_await 507.69 28.40 33.68
Max sda-avgqz 680.60 12.25 23.14
Max sda-await 3958.89 221.83 286.22
Max sda-r_await 63.86 61.23 67.29
Max sda-w_await 11710.38 883.57 1767.28
And as before, write wait times are much reduced.
This patch:
The patch "mm: vmscan: Have kswapd writeback pages based on dirty pages
encountered, not priority" decides whether to writeback pages from reclaim
context based on the number of dirty pages encountered. This situation is
flagged too easily and flushers are not given the chance to catch up
resulting in more pages being written from reclaim context and potentially
impacting IO performance. The check for PageWriteback is also misplaced
as it happens within a PageDirty check which is nonsense as the dirty may
have been cleared for IO. The accounting is updated very late and pages
that are already under writeback, were reactivated, could not unmapped or
could not be released are all missed. Similarly, a page is considered
congested for reasons other than being congested and pages that cannot be
written out in the correct context are skipped. Finally, it considers
stalling and writing back filesystem pages due to encountering dirty
anonymous pages at the tail of the LRU which is dumb.
This patch causes kswapd to begin writing filesystem pages from reclaim
context only if page reclaim found that all filesystem pages at the tail
of the LRU were unqueued dirty pages. Before it starts writing filesystem
pages, it will stall to give flushers a chance to catch up. The decision
on whether wait_iff_congested is also now determined by dirty filesystem
pages only. Congested pages are based on whether the underlying BDI is
congested regardless of the context of the reclaiming process.
mm: vmscan: move logic from balance_pgdat() to kswapd_shrink_zone()
balance_pgdat() is very long and some of the logic can and should be
internal to kswapd_shrink_zone(). Move it so the flow of
balance_pgdat() is marginally easier to follow.
mm: vmscan: check if kswapd should writepage once per pgdat scan
Currently kswapd checks if it should start writepage as it shrinks each
zone without taking into consideration if the zone is balanced or not.
This is not wrong as such but it does not make much sense either. This
patch checks once per pgdat scan if kswapd should be writing pages.
mm: vmscan: block kswapd if it is encountering pages under writeback
Historically, kswapd used to congestion_wait() at higher priorities if
it was not making forward progress. This made no sense as the failure
to make progress could be completely independent of IO. It was later
replaced by wait_iff_congested() and removed entirely by commit 258401a6
(mm: don't wait on congested zones in balance_pgdat()) as it was
duplicating logic in shrink_inactive_list().
This is problematic. If kswapd encounters many pages under writeback
and it continues to scan until it reaches the high watermark then it
will quickly skip over the pages under writeback and reclaim clean young
pages or push applications out to swap.
The use of wait_iff_congested() is not suited to kswapd as it will only
stall if the underlying BDI is really congested or a direct reclaimer
was unable to write to the underlying BDI. kswapd bypasses the BDI
congestion as it sets PF_SWAPWRITE but even if this was taken into
account then it would cause direct reclaimers to stall on writeback
which is not desirable.
This patch sets a ZONE_WRITEBACK flag if direct reclaim or kswapd is
encountering too many pages under writeback. If this flag is set and
kswapd encounters a PageReclaim page under writeback then it'll assume
that the LRU lists are being recycled too quickly before IO can complete
and block waiting for some IO to complete.
mm: vmscan: have kswapd writeback pages based on dirty pages encountered, not priority
Currently kswapd queues dirty pages for writeback if scanning at an
elevated priority but the priority kswapd scans at is not related to the
number of unqueued dirty encountered. Since commit "mm: vmscan: Flatten
kswapd priority loop", the priority is related to the size of the LRU
and the zone watermark which is no indication as to whether kswapd
should write pages or not.
This patch tracks if an excessive number of unqueued dirty pages are
being encountered at the end of the LRU. If so, it indicates that dirty
pages are being recycled before flusher threads can clean them and flags
the zone so that kswapd will start writing pages until the zone is
balanced.
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