| From | Andi Kleen <> | Subject | [PATCH] [180/223] perf_events: Fix perf_counter_mmap() hook in mprotect() | Date | Mon, 13 Dec 2010 00:48:05 +0100 (CET) |
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2.6.35-longterm review patch. If anyone has any objections, please let me know.
------------------ From: Pekka Enberg <penberg@kernel.org>
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> Signed-off-by: Andi Kleen <ak@linux.intel.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: Greg Kroah-Hartman <gregkh@suse.de>
--- mm/mprotect.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
Index: linux/mm/mprotect.c =================================================================== --- linux.orig/mm/mprotect.c +++ linux/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, 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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