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slub: move discard_slab out of node lock 

Lockdep reports there is potential deadlock for slub node list_lock.
discard_slab() is called with the lock hold in unfreeze_partials(),
which could trigger a slab allocation, which could hold the lock again.

discard_slab() doesn't need hold the lock actually, if the slab is
already removed from partial list.

Acked-by: Christoph Lameter <cl@linux.com>
Reported-and-tested-by: Yong Zhang <yong.zhang0@gmail.com>
Reported-and-tested-by: Julie Sullivan <kernelmail.jms@gmail.com>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
hifive-unleashed-5.1
Shaohua Li 2011-11-14 13:34:13 +08:00 committed by Pekka Enberg
parent f64ae042d9
commit 9ada19342b
1 changed files with 12 additions and 4 deletions
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16
mm/slub.c
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@ -1862,7 +1862,7 @@ static void unfreeze_partials(struct kmem_cache *s)
{
struct kmem_cache_node *n = NULL;
struct kmem_cache_cpu *c = this_cpu_ptr(s->cpu_slab);
struct page *page;
struct page *page, *discard_page = NULL;
while ((page = c->partial)) {
enum slab_modes { M_PARTIAL, M_FREE };
@ -1916,14 +1916,22 @@ static void unfreeze_partials(struct kmem_cache *s)
"unfreezing slab"));
if (m == M_FREE) {
stat(s, DEACTIVATE_EMPTY);
discard_slab(s, page);
stat(s, FREE_SLAB);
page->next = discard_page;
discard_page = page;
}
}
if (n)
spin_unlock(&n->list_lock);
while (discard_page) {
page = discard_page;
discard_page = discard_page->next;
stat(s, DEACTIVATE_EMPTY);
discard_slab(s, page);
stat(s, FREE_SLAB);
}
}
/*