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Jan Stancek b6a9b7f6b1 mm: prevent mmap_cache race in find_vma() 
find_vma() can be called by multiple threads with read lock
held on mm->mmap_sem and any of them can update mm->mmap_cache.
Prevent compiler from re-fetching mm->mmap_cache, because other
readers could update it in the meantime:

               thread 1                             thread 2
                                        |
  find_vma()                            |  find_vma()
    struct vm_area_struct *vma = NULL;  |
    vma = mm->mmap_cache;               |
    if (!(vma && vma->vm_end > addr     |
        && vma->vm_start <= addr)) {    |
                                        |    mm->mmap_cache = vma;
    return vma;                         |
     ^^ compiler may optimize this      |
        local variable out and re-read  |
        mm->mmap_cache                  |

This issue can be reproduced with gcc-4.8.0-1 on s390x by running
mallocstress testcase from LTP, which triggers:

  kernel BUG at mm/rmap.c:1088!
    Call Trace:
     ([<000003d100c57000>] 0x3d100c57000)
      [<000000000023a1c0>] do_wp_page+0x2fc/0xa88
      [<000000000023baae>] handle_pte_fault+0x41a/0xac8
      [<000000000023d832>] handle_mm_fault+0x17a/0x268
      [<000000000060507a>] do_protection_exception+0x1e2/0x394
      [<0000000000603a04>] pgm_check_handler+0x138/0x13c
      [<000003fffcf1f07a>] 0x3fffcf1f07a
    Last Breaking-Event-Address:
      [<000000000024755e>] page_add_new_anon_rmap+0xc2/0x168

Thanks to Jakub Jelinek for his insight on gcc and helping to
track this down.

Signed-off-by: Jan Stancek <jstancek@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-04-04 11:46:28 -07:00
..
backing-dev.c bdi: allow block devices to say that they require stable page writes 2013-02-21 17:22:19 -08:00
balloon_compaction.c mm: introduce a common interface for balloon pages mobility 2012-12-11 17:22:26 -08:00
bootmem.c mm: Add alloc_bootmem_low_pages_nopanic() 2013-01-29 19:32:59 -08:00
bounce.c block: optionally snapshot page contents to provide stable pages during write 2013-02-21 17:22:20 -08:00
cleancache.c fs: encode_fh: return FILEID_INVALID if invalid fid_type 2013-02-26 02:46:10 -05:00
compaction.c mm: add & use zone_end_pfn() and zone_spans_pfn() 2013-02-23 17:50:20 -08:00
debug-pagealloc.c
dmapool.c dmapool: make DMAPOOL_DEBUG detect corruption of free marker 2012-12-11 17:22:24 -08:00
fadvise.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
failslab.c
filemap.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
filemap_xip.c mm: move all mmu notifier invocations to be done outside the PT lock 2012-10-09 16:22:58 +09:00
fremap.c Revert "mm: introduce VM_POPULATE flag to better deal with racy userspace programs" 2013-03-28 17:45:51 -07:00
frontswap.c
highmem.c Some nice cleanups, and even a patch my wife did as a "live" demo for 2012-12-20 08:37:05 -08:00
huge_memory.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
hugetlb.c mm/hugetlb: fix total hugetlbfs pages count when using memory overcommit accouting 2013-03-22 16:41:20 -07:00
hugetlb_cgroup.c mm/hugetlb: create hugetlb cgroup file in hugetlb_init 2012-12-18 15:02:15 -08:00
hwpoison-inject.c
init-mm.c
internal.h mm: accelerate munlock() treatment of THP pages 2013-02-27 19:10:09 -08:00
interval_tree.c
Kconfig Select VIRT_TO_BUS directly where needed 2013-03-12 11:16:40 -07:00
Kconfig.debug
kmemcheck.c
kmemleak-test.c
kmemleak.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
ksm.c ksm: fix m68k build: only NUMA needs pfn_to_nid 2013-03-08 15:05:34 -08:00
maccess.c
madvise.c mm: make madvise(MADV_WILLNEED) support swap file prefetch 2013-02-23 17:50:10 -08:00
Makefile mm: introduce a common interface for balloon pages mobility 2012-12-11 17:22:26 -08:00
memblock.c x86, ACPI, mm: Revert movablemem_map support 2013-03-02 09:34:39 -08:00
memcontrol.c memcg: initialize kmem-cache destroying work earlier 2013-03-08 15:05:34 -08:00
memory-failure.c HWPOISON: change order of error_states[]'s elements 2013-02-23 17:50:22 -08:00
memory.c The sweeping change is to make add_taint() explicitly indicate whether to disable 2013-02-25 15:41:43 -08:00
memory_hotplug.c mm/hotplug: only free wait_table if it's allocated by vmalloc 2013-03-22 16:41:20 -07:00
mempolicy.c mm/mempolicy.c: fix sp_node_init() argument ordering 2013-03-08 15:05:34 -08:00
mempool.c
migrate.c mm: remove offlining arg to migrate_pages 2013-02-23 17:50:19 -08:00
mincore.c swap: make each swap partition have one address_space 2013-02-23 17:50:17 -08:00
mlock.c Revert "mm: introduce VM_POPULATE flag to better deal with racy userspace programs" 2013-03-28 17:45:51 -07:00
mm_init.c mm: init: report on last-nid information stored in page->flags 2013-02-23 17:50:18 -08:00
mmap.c mm: prevent mmap_cache race in find_vma() 2013-04-04 11:46:28 -07:00
mmu_context.c
mmu_notifier.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
mmzone.c mm: rename page struct field helpers 2013-02-23 17:50:18 -08:00
mprotect.c mm/mprotect.c: coding-style cleanups 2012-12-18 15:02:15 -08:00
mremap.c mm/rmap: rename anon_vma_unlock() => anon_vma_unlock_write() 2013-02-23 17:50:17 -08:00
msync.c
nobootmem.c mm: Add alloc_bootmem_low_pages_nopanic() 2013-01-29 19:32:59 -08:00
nommu.c mm: prevent mmap_cache race in find_vma() 2013-04-04 11:46:28 -07:00
oom_kill.c memcg, oom: provide more precise dump info while memcg oom happening 2013-02-23 17:50:08 -08:00
page-writeback.c 2 writeback fixes 2013-02-28 13:21:44 -08:00
page_alloc.c x86, ACPI, mm: Revert movablemem_map support 2013-03-02 09:34:39 -08:00
page_cgroup.c memcontrol: use N_MEMORY instead N_HIGH_MEMORY 2012-12-12 17:38:32 -08:00
page_io.c
page_isolation.c mm: fix zone_watermark_ok_safe() accounting of isolated pages 2013-01-04 16:11:46 -08:00
pagewalk.c thp: change split_huge_page_pmd() interface 2012-12-12 17:38:31 -08:00
percpu-km.c
percpu-vm.c
percpu.c mm, percpu: Make sure percpu_alloc early parameter has an argument 2012-12-02 06:23:04 -08:00
pgtable-generic.c mm: Only flush the TLB when clearing an accessible pte 2012-12-11 14:28:34 +00:00
process_vm_access.c Fix: compat_rw_copy_check_uvector() misuse in aio, readv, writev, and security keys 2013-03-12 11:05:45 -07:00
quicklist.c
readahead.c
rmap.c mm/rmap: rename anon_vma_unlock() => anon_vma_unlock_write() 2013-02-23 17:50:17 -08:00
shmem.c fix nommu breakage in shmem.c 2013-03-01 23:50:45 -05:00
slab.c taint: add explicit flag to show whether lock dep is still OK. 2013-01-21 17:17:57 +10:30
slab.h slab: propagate tunable values 2012-12-18 15:02:14 -08:00
slab_common.c slab: propagate tunable values 2012-12-18 15:02:14 -08:00
slob.c mm: rename page struct field helpers 2013-02-23 17:50:18 -08:00
slub.c The sweeping change is to make add_taint() explicitly indicate whether to disable 2013-02-25 15:41:43 -08:00
sparse-vmemmap.c
sparse.c memory-failure: use num_poisoned_pages instead of mce_bad_pages 2013-02-23 17:50:15 -08:00
swap.c swap: make each swap partition have one address_space 2013-02-23 17:50:17 -08:00
swap_state.c swap: add per-partition lock for swapfile 2013-02-23 17:50:17 -08:00
swapfile.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-02-26 20:16:07 -08:00
truncate.c mm: drop vmtruncate 2012-12-20 18:46:29 -05:00
util.c swap: make each swap partition have one address_space 2013-02-23 17:50:17 -08:00
vmalloc.c mm: use NUMA_NO_NODE 2013-02-23 17:50:21 -08:00
vmscan.c vmscan: change type of vm_total_pages to unsigned long 2013-02-23 17:50:22 -08:00
vmstat.c mm: add & use zone_end_pfn() and zone_spans_pfn() 2013-02-23 17:50:20 -08:00