Peter Zijlstra 535fad87e8 perf: Fix perf mmap bugs ... commit 26cb63ad11 upstream. Vince reported a problem found by his perf specific trinity fuzzer. Al noticed 2 problems with perf's mmap(): - it has issues against fork() since we use vma->vm_mm for accounting. - it has an rb refcount leak on double mmap(). We fix the issues against fork() by using VM_DONTCOPY; I don't think there's code out there that uses this; we didn't hear about weird accounting problems/crashes. If we do need this to work, the previously proposed VM_PINNED could make this work. Aside from the rb reference leak spotted by Al, Vince's example prog was indeed doing a double mmap() through the use of perf_event_set_output(). This exposes another problem, since we now have 2 events with one buffer, the accounting gets screwy because we account per event. Fix this by making the buffer responsible for its own accounting. [Backporting for 3.4-stable. VM_RESERVED flag was replaced with pair 'VM_DONTEXPAND | VM_DONTDUMP' in 314e51b9 since 3.7.0-rc1, and 314e51b9 comes from a big patchset, we didn't backport the patchset, so I restored 'VM_DNOTEXPAND | VM_DONTDUMP' as before: - vma->vm_flags |= VM_DONTCOPY | VM_DONTEXPAND | VM_DONTDUMP; + vma->vm_flags |= VM_DONTCOPY | VM_RESERVED; -- zliu] Reported-by: Vince Weaver <vincent.weaver@maine.edu> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Paul Mackerras <paulus@samba.org> Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net> Link: http://lkml.kernel.org/r/20130528085548.GA12193@twins.programming.kicks-ass.net Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Zhouping Liu <zliu@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>		2013-07-03 10:59:06 -07:00
..
callchain.c	perf: Don't call release_callchain_buffers() if allocation fails	2012-01-21 09:33:41 +01:00
core.c	perf: Fix perf mmap bugs	2013-07-03 10:59:06 -07:00
hw_breakpoint.c	hw_breakpoint: Use cpu_possible_mask in {reserve,release}_bp_slot()	2013-07-03 10:59:01 -07:00
internal.h	perf: Fix perf mmap bugs	2013-07-03 10:59:06 -07:00
Makefile	perf: Carve out callchain functionality	2011-11-14 13:31:26 +01:00
ring_buffer.c	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/trivial	2012-01-08 13:21:22 -08:00