mm, slub: consider rest of partial list if acquire_slab() fails

iv/linux

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: 7ced371971 ("slub: Acquire_slab() avoid loop")
Signed-off-by: Jann Horn <jannh@google.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This commit is contained in:

Jann Horn

2021-01-12 15:49:04 -08:00

committed by

Linus Torvalds

parent e609571b5f

commit 8ff60eb052

1 changed files with 1 additions and 1 deletions

									
										2

mm/slub.c
									
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				@ -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) {

mm, slub: consider rest of partial list if acquire_slab() fails

2 mm/slub.c Unescape Escape View File

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mm/slub.c

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