Messages in this thread Patch in this message | | | From | Paul Gortmaker <> | Subject | [34-longterm 095/209] perf_events: Fix perf_counter_mmap() hook in mprotect() | Date | Thu, 14 Apr 2011 13:42:05 -0400 |
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From: Pekka Enberg <penberg@kernel.org>
===================================================================== | This is a commit scheduled for the next v2.6.34 longterm release. | | If you see a problem with using this for longterm, please comment.| =====================================================================
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 mprotect_fixup().
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 executable.
Reported-by: Dave Jones <davej@redhat.com> Analyzed-by: Linus Torvalds <torvalds@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu> Reviewed-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Pekka Enberg <penberg@kernel.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> --- mm/mprotect.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/mm/mprotect.c b/mm/mprotect.c index 2d1bf7c..4c51338 100644 --- 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; fail: @@ -299,7 +300,6 @@ SYSCALL_DEFINE3(mprotect, unsigned long, start, size_t, len, error = mprotect_fixup(vma, &prev, nstart, tmp, newflags); if (error) goto out; - perf_event_mmap(vma); nstart = tmp; if (nstart < prev->vm_end) -- 1.7.4.4
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