The patch titled
Subject: perf: fix perf bug in fork()
has been added to the -mm tree. Its filename is
perf-fix-perf-bug-in-fork.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/perf-fix-perf-bug-in-fork.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/perf-fix-perf-bug-in-fork.patch
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The -mm tree is included into linux-next and is updated
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------------------------------------------------------
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Subject: perf: fix perf bug in fork()
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@xxxxxxxxxx>
Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Reported-by: Sylvain 'ythier' Hitier <sylvain.hitier@xxxxxxxxx>
Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/events/core.c | 4 +++-
kernel/fork.c | 5 +++--
2 files changed, 6 insertions(+), 3 deletions(-)
diff -puN kernel/events/core.c~perf-fix-perf-bug-in-fork kernel/events/core.c
--- a/kernel/events/core.c~perf-fix-perf-bug-in-fork
+++ a/kernel/events/core.c
@@ -7948,8 +7948,10 @@ int perf_event_init_task(struct task_str
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;
diff -puN kernel/fork.c~perf-fix-perf-bug-in-fork kernel/fork.c
--- a/kernel/fork.c~perf-fix-perf-bug-in-fork
+++ a/kernel/fork.c
@@ -1360,7 +1360,7 @@ static struct task_struct *copy_process(
goto bad_fork_cleanup_policy;
retval = audit_alloc(p);
if (retval)
- goto bad_fork_cleanup_policy;
+ goto bad_fork_cleanup_perf;
/* copy all the process information */
shm_init_task(p);
retval = copy_semundo(clone_flags, p);
@@ -1566,8 +1566,9 @@ bad_fork_cleanup_semundo:
exit_sem(p);
bad_fork_cleanup_audit:
audit_free(p);
-bad_fork_cleanup_policy:
+bad_fork_cleanup_perf:
perf_event_free_task(p);
+bad_fork_cleanup_policy:
#ifdef CONFIG_NUMA
mpol_put(p->mempolicy);
bad_fork_cleanup_threadgroup_lock:
_
Patches currently in -mm which might be from peterz@xxxxxxxxxxxxx are
mm-memcontrol-do-not-iterate-uninitialized-memcgs.patch
perf-fix-perf-bug-in-fork.patch
mempolicy-change-alloc_pages_vma-to-use-mpol_cond_put.patch
mempolicy-change-get_task_policy-to-return-default_policy-rather-than-null.patch
mempolicy-sanitize-the-usage-of-get_task_policy.patch
mempolicy-remove-the-task-arg-of-vma_policy_mof-and-simplify-it.patch
mempolicy-introduce-__get_vma_policy-export-get_task_policy.patch
mempolicy-fix-show_numa_map-vs-exec-do_set_mempolicy-race.patch
mempolicy-kill-do_set_mempolicy-down_writemm-mmap_sem.patch
mempolicy-unexport-get_vma_policy-and-remove-its-task-arg.patch
vmstat-on-demand-vmstat-workers-v8.patch
vmstat-on-demand-vmstat-workers-v8-do-not-open-code-alloc_cpumask_var.patch
printk-git-rid-of-message-for-printk_deferred.patch
lib-remove-prio_heap.patch
x86-optimize-resource-lookups-for-ioremap.patch
x86-optimize-resource-lookups-for-ioremap-fix.patch
x86-use-optimized-ioresource-lookup-in-ioremap-function.patch
linux-next.patch
mm-replace-remap_file_pages-syscall-with-emulation.patch
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