]> git.proxmox.com Git - mirror_ubuntu-jammy-kernel.git/commit - mm/kmemleak.c
mm/kmemleak: avoid scanning potential huge holes
authorLang Yu <lang.yu@amd.com>
Fri, 4 Feb 2022 04:49:37 +0000 (20:49 -0800)
committerPaolo Pisati <paolo.pisati@canonical.com>
Thu, 10 Feb 2022 14:31:30 +0000 (15:31 +0100)
commit02fd61908f9a595776bfa764cac9b17b3de10c5d
tree1b54432595fb04f52193ee7928efe2fc51d345e4
parent0bb5543b5a14f5bb84f1651de1757d9c15deebba
mm/kmemleak: avoid scanning potential huge holes

BugLink: https://bugs.launchpad.net/bugs/1960516
commit c10a0f877fe007021d70f9cada240f42adc2b5db upstream.

When using devm_request_free_mem_region() and devm_memremap_pages() to
add ZONE_DEVICE memory, if requested free mem region's end pfn were
huge(e.g., 0x400000000), the node_end_pfn() will be also huge (see
move_pfn_range_to_zone()).  Thus it creates a huge hole between
node_start_pfn() and node_end_pfn().

We found on some AMD APUs, amdkfd requested such a free mem region and
created a huge hole.  In such a case, following code snippet was just
doing busy test_bit() looping on the huge hole.

  for (pfn = start_pfn; pfn < end_pfn; pfn++) {
struct page *page = pfn_to_online_page(pfn);
if (!page)
continue;
...
  }

So we got a soft lockup:

  watchdog: BUG: soft lockup - CPU#6 stuck for 26s! [bash:1221]
  CPU: 6 PID: 1221 Comm: bash Not tainted 5.15.0-custom #1
  RIP: 0010:pfn_to_online_page+0x5/0xd0
  Call Trace:
    ? kmemleak_scan+0x16a/0x440
    kmemleak_write+0x306/0x3a0
    ? common_file_perm+0x72/0x170
    full_proxy_write+0x5c/0x90
    vfs_write+0xb9/0x260
    ksys_write+0x67/0xe0
    __x64_sys_write+0x1a/0x20
    do_syscall_64+0x3b/0xc0
    entry_SYSCALL_64_after_hwframe+0x44/0xae

I did some tests with the patch.

(1) amdgpu module unloaded

before the patch:

  real    0m0.976s
  user    0m0.000s
  sys     0m0.968s

after the patch:

  real    0m0.981s
  user    0m0.000s
  sys     0m0.973s

(2) amdgpu module loaded

before the patch:

  real    0m35.365s
  user    0m0.000s
  sys     0m35.354s

after the patch:

  real    0m1.049s
  user    0m0.000s
  sys     0m1.042s

Link: https://lkml.kernel.org/r/20211108140029.721144-1-lang.yu@amd.com
Signed-off-by: Lang Yu <lang.yu@amd.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Paolo Pisati <paolo.pisati@canonical.com>
mm/kmemleak.c