The patch titled
Subject: fork: copy mm's vm usage counters under mmap_sem
has been added to the -mm tree. Its filename is
fork-copy-mms-vm-usage-counters-under-mmap_sem.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fork-copy-mms-vm-usage-counters-under-mmap_sem.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fork-copy-mms-vm-usage-counters-under-mmap_sem.patch
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------------------------------------------------------
From: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Subject: fork: copy mm's vm usage counters under mmap_sem
If a forking process has a thread calling (un)mmap (silly but still),
the child process may have some of its mm's vm usage counters (total_vm
and friends) screwed up, because currently they are copied from oldmm
w/o holding any locks (memcpy in dup_mm).
This patch moves the counters initialization to dup_mmap() to be called
under oldmm->mmap_sem, which eliminates any possibility of race.
Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/fork.c | 5 +++++
1 file changed, 5 insertions(+)
diff -puN kernel/fork.c~fork-copy-mms-vm-usage-counters-under-mmap_sem kernel/fork.c
--- a/kernel/fork.c~fork-copy-mms-vm-usage-counters-under-mmap_sem
+++ a/kernel/fork.c
@@ -365,6 +365,11 @@ static int dup_mmap(struct mm_struct *mm
*/
down_write_nested(&mm->mmap_sem, SINGLE_DEPTH_NESTING);
+ mm->total_vm = oldmm->total_vm;
+ mm->shared_vm = oldmm->shared_vm;
+ mm->exec_vm = oldmm->exec_vm;
+ mm->stack_vm = oldmm->stack_vm;
+
rb_link = &mm->mm_rb.rb_node;
rb_parent = NULL;
pprev = &mm->mmap;
_
Patches currently in -mm which might be from vdavydov@xxxxxxxxxxxxx are
slab-fix-oops-when-reading-proc-slab_allocators.patch
slab-fix-oops-when-reading-proc-slab_allocators-v2.patch
mm-slabh-wrap-the-whole-file-with-guarding-macro.patch
memcg-cleanup-memcg_cache_params-refcnt-usage.patch
memcg-destroy-kmem-caches-when-last-slab-is-freed.patch
memcg-mark-caches-that-belong-to-offline-memcgs-as-dead.patch
slub-dont-fail-kmem_cache_shrink-if-slab-placement-optimization-fails.patch
slub-make-slab_free-non-preemptable.patch
memcg-wait-for-kfrees-to-finish-before-destroying-cache.patch
slub-make-dead-memcg-caches-discard-free-slabs-immediately.patch
slab-do-not-keep-free-objects-slabs-on-dead-memcg-caches.patch
mm-memcontrol-fold-mem_cgroup_do_charge.patch
mm-memcontrol-rearrange-charging-fast-path.patch
mm-memcontrol-reclaim-at-least-once-for-__gfp_noretry.patch
mm-huge_memory-use-gfp_transhuge-when-charging-huge-pages.patch
mm-memcontrol-retry-reclaim-for-oom-disabled-and-__gfp_nofail-charges.patch
mm-memcontrol-remove-explicit-oom-parameter-in-charge-path.patch
mm-memcontrol-simplify-move-precharge-function.patch
mm-memcontrol-catch-root-bypass-in-move-precharge.patch
mm-memcontrol-use-root_mem_cgroup-res_counter.patch
mm-memcontrol-remove-ordering-between-pc-mem_cgroup-and-pagecgroupused.patch
mm-memcontrol-do-not-acquire-page_cgroup-lock-for-kmem-pages.patch
mm-memcontrol-rewrite-charge-api.patch
mm-memcontrol-rewrite-charge-api-fix.patch
mm-memcontrol-rewrite-uncharge-api.patch
mm-memcontrol-rewrite-uncharge-api-fix.patch
fork-exec-cleanup-mm-initialization.patch
fork-reset-mm-pinned_vm.patch
fork-copy-mms-vm-usage-counters-under-mmap_sem.patch
linux-next.patch
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