diff options
| author | Vlastimil Babka <vbabka@suse.cz> | 2014-03-03 15:38:27 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-03-04 07:55:48 -0800 |
| commit | 9050d7eba40b3d79551668f54e68fd6f51945ef3 (patch) | |
| tree | 6d772855aeb487b138c2812b3e7860d8df708ec3 /mm | |
| parent | 4fb1a86fb5e4209a7d4426d4e586c58e9edc74ac (diff) | |
mm: include VM_MIXEDMAP flag in the VM_SPECIAL list to avoid m(un)locking
Daniel Borkmann reported a VM_BUG_ON assertion failing:
------------[ cut here ]------------
kernel BUG at mm/mlock.c:528!
invalid opcode: 0000 [#1] SMP
Modules linked in: ccm arc4 iwldvm [...]
video
CPU: 3 PID: 2266 Comm: netsniff-ng Not tainted 3.14.0-rc2+ #8
Hardware name: LENOVO 2429BP3/2429BP3, BIOS G4ET37WW (1.12 ) 05/29/2012
task: ffff8801f87f9820 ti: ffff88002cb44000 task.ti: ffff88002cb44000
RIP: 0010:[<ffffffff81171ad0>] [<ffffffff81171ad0>] munlock_vma_pages_range+0x2e0/0x2f0
Call Trace:
do_munmap+0x18f/0x3b0
vm_munmap+0x41/0x60
SyS_munmap+0x22/0x30
system_call_fastpath+0x1a/0x1f
RIP munlock_vma_pages_range+0x2e0/0x2f0
---[ end trace a0088dcf07ae10f2 ]---
because munlock_vma_pages_range() thinks it's unexpectedly in the middle
of a THP page. This can be reproduced with default config since 3.11
kernels. A reproducer can be found in the kernel's selftest directory
for networking by running ./psock_tpacket.
The problem is that an order=2 compound page (allocated by
alloc_one_pg_vec_page() is part of the munlocked VM_MIXEDMAP vma (mapped
by packet_mmap()) and mistaken for a THP page and assumed to be order=9.
The checks for THP in munlock came with commit ff6a6da60b89 ("mm:
accelerate munlock() treatment of THP pages"), i.e. since 3.9, but did
not trigger a bug. It just makes munlock_vma_pages_range() skip such
compound pages until the next 512-pages-aligned page, when it encounters
a head page. This is however not a problem for vma's where mlocking has
no effect anyway, but it can distort the accounting.
Since commit 7225522bb429 ("mm: munlock: batch non-THP page isolation
and munlock+putback using pagevec") this can trigger a VM_BUG_ON in
PageTransHuge() check.
This patch fixes the issue by adding VM_MIXEDMAP flag to VM_SPECIAL, a
list of flags that make vma's non-mlockable and non-mergeable. The
reasoning is that VM_MIXEDMAP vma's are similar to VM_PFNMAP, which is
already on the VM_SPECIAL list, and both are intended for non-LRU pages
where mlocking makes no sense anyway. Related Lkml discussion can be
found in [2].
[1] tools/testing/selftests/net/psock_tpacket
[2] https://lkml.org/lkml/2014/1/10/427
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Reported-by: Daniel Borkmann <dborkman@redhat.com>
Tested-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Thomas Hellstrom <thellstrom@vmware.com>
Cc: John David Anglin <dave.anglin@bell.net>
Cc: HATAYAMA Daisuke <d.hatayama@jp.fujitsu.com>
Cc: Konstantin Khlebnikov <khlebnikov@openvz.org>
Cc: Carsten Otte <cotte@de.ibm.com>
Cc: Jared Hulbert <jaredeh@gmail.com>
Tested-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org> [3.11.x+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/huge_memory.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/huge_memory.c b/mm/huge_memory.c index 4df39b1bde91..1546655a2d78 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -1961,7 +1961,7 @@ out: return ret; } -#define VM_NO_THP (VM_SPECIAL|VM_MIXEDMAP|VM_HUGETLB|VM_SHARED|VM_MAYSHARE) +#define VM_NO_THP (VM_SPECIAL | VM_HUGETLB | VM_SHARED | VM_MAYSHARE) int hugepage_madvise(struct vm_area_struct *vma, unsigned long *vm_flags, int advice) |