From 9ada19342b2441f290f0043ed7c562682c8c4ede Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Mon, 14 Nov 2011 13:34:13 +0800 Subject: 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 Reported-and-tested-by: Yong Zhang Reported-and-tested-by: Julie Sullivan Signed-off-by: Shaohua Li Signed-off-by: Pekka Enberg --- mm/slub.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/mm/slub.c b/mm/slub.c index 60e16c43f88..00efbb56a26 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -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); + } } /* -- cgit v1.2.3-70-g09d2