From 8ff60eb052eeba95cfb3efe16b08c9199f8121cf Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Tue, 12 Jan 2021 15:49:04 -0800 Subject: [PATCH] mm, slub: consider rest of partial list if acquire_slab() fails acquire_slab() fails if there is contention on the freelist of the page (probably because some other CPU is concurrently freeing an object from the page). In that case, it might make sense to look for a different page (since there might be more remote frees to the page from other CPUs, and we don't want contention on struct page). However, the current code accidentally stops looking at the partial list completely in that case. Especially on kernels without CONFIG_NUMA set, this means that get_partial() fails and new_slab_objects() falls back to new_slab(), allocating new pages. This could lead to an unnecessary increase in memory fragmentation. Link: https://lkml.kernel.org/r/20201228130853.1871516-1-jannh@google.com Fixes: 7ced37197196 ("slub: Acquire_slab() avoid loop") Signed-off-by: Jann Horn Acked-by: David Rientjes Acked-by: Joonsoo Kim Cc: Christoph Lameter Cc: Pekka Enberg Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slub.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/slub.c b/mm/slub.c index dc5b42e..d9e4e10 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1973,7 +1973,7 @@ static void *get_partial_node(struct kmem_cache *s, struct kmem_cache_node *n, t = acquire_slab(s, n, page, object == NULL, &objects); if (!t) - break; + continue; /* cmpxchg raced */ available += objects; if (!object) { -- 2.7.4