Messages in this thread Patch in this message | | | Subject | Re: [Slub allocator] There are chances that kmem_cache_cpu->freelist gets lost if the process happens to be rescheduled to a differenet cpu before the local_irq_save() completes in __slab_alloc() | From | Eric Dumazet <> | Date | Mon, 12 Dec 2011 18:39:18 +0100 |
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Le lundi 12 décembre 2011 à 09:50 -0600, Christoph Lameter a écrit :
> Correct. Issue was introduced in 2.6.39. > > Acked-by: Christoph Lameter <cl@linux.com> >
Indeed, I reproduced the leak with hackbench and lot of threads.
Thanks
[PATCH] slub: fix a possible memleak in __slab_alloc()
Zhihua Che reported a possible memleak in slub allocator on CONFIG_PREEMPT=y builds.
It is possible current thread migrates right before disabling irqs in __slab_alloc(). We must check again c->freelist, and perform a normal allocation instead of scratching c->freelist.
Many thanks to Zhihua Che for spotting this bug, introduced in 2.6.39
Reported-by: zhihua che <zhihua.che@gmail.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> Acked-by: Christoph Lameter <cl@linux.com> CC: Pekka Enberg <penberg@cs.helsinki.fi> CC: stable@vger.kernel.org --- mm/slub.c | 6 ++++++ 1 file changed, 6 insertions(+)
diff --git a/mm/slub.c b/mm/slub.c index ed3334d..923d238 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -2166,6 +2166,12 @@ redo: goto new_slab; } +#ifdef CONFIG_PREEMPT + object = c->freelist; + if (object) + goto load_freelist; +#endif + stat(s, ALLOC_SLOWPATH); do {
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