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Subject[239/289] perf_events: Fix perf_counter_mmap() hook in mprotect()
2.6.36-stable review patch.  If anyone has any objections, please let us know.

From: Pekka Enberg <>

commit 63bfd7384b119409685a17d5c58f0b56e5dc03da upstream.

As pointed out by Linus, commit dab5855 ("perf_counter: Add mmap event hooks to
mprotect()") is fundamentally wrong as mprotect_fixup() can free 'vma' due to
merging. Fix the problem by moving perf_event_mmap() hook to

Note: there's another successful return path from mprotect_fixup() if old
flags equal to new flags. We don't, however, need to call
perf_event_mmap() there because 'perf' already knows the VMA is

Reported-by: Dave Jones <>
Analyzed-by: Linus Torvalds <>
Cc: Ingo Molnar <>
Reviewed-by: Peter Zijlstra <>
Signed-off-by: Pekka Enberg <>
Signed-off-by: Linus Torvalds <>
Signed-off-by: Greg Kroah-Hartman <>

mm/mprotect.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -211,6 +211,7 @@ success:
mmu_notifier_invalidate_range_end(mm, start, end);
vm_stat_account(mm, oldflags, vma->vm_file, -nrpages);
vm_stat_account(mm, newflags, vma->vm_file, nrpages);
+ perf_event_mmap(vma);
return 0;

@@ -299,7 +300,6 @@ SYSCALL_DEFINE3(mprotect, unsigned long,
error = mprotect_fixup(vma, &prev, nstart, tmp, newflags);
if (error)
goto out;
- perf_event_mmap(vma);
nstart = tmp;

if (nstart < prev->vm_end)

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