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perf: fix perf bug in fork()

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Oleg noticed that a cleanup by Sylvain actually uncovered a bug; by
calling perf_event_free_task() when failing sched_fork() we will not yet
have done the memset() on ->perf_event_ctxp[] and will therefore try and
'free' the inherited contexts, which are still in use by the parent
process.  This is bad..

Suggested-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Sylvain 'ythier' Hitier <sylvain.hitier@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Peter Zijlstra
2014-10-02 16:17:02 -07:00
committed by Linus Torvalds
parent cba5b1c6e2
commit 6c72e3501d
2 changed files with 6 additions and 3 deletions
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4
kernel/events/core.c
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@@ -7948,8 +7948,10 @@ int perf_event_init_task(struct task_struct *child)
for_each_task_context_nr(ctxn) {
ret = perf_event_init_context(child, ctxn);
if (ret)
if (ret) {
perf_event_free_task(child);
return ret;
}
}
return 0;