The patch titled
Subject: slub: fix __kmem_cache_empty for !CONFIG_SLUB_DEBUG
has been added to the -mm tree. Its filename is
slub-fix-__kmem_cache_empty-for-config_slub_debug.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/slub-fix-__kmem_cache_empty-for-config_slub_debug.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/slub-fix-__kmem_cache_empty-for-config_slub_debug.patch
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------------------------------------------------------
From: Shakeel Butt <shakeelb@xxxxxxxxxx>
Subject: slub: fix __kmem_cache_empty for !CONFIG_SLUB_DEBUG
f9e13c0a5a33 ("slab, slub: skip unnecessary kasan_cache_shutdown()")
causes crashes when using slub, as described at
http://lkml.kernel.org/r/CAHmME9rtoPwxUSnktxzKso14iuVCWT7BE_-_8PAC=pGw1iJnQg@xxxxxxxxxxxxxx
For !CONFIG_SLUB_DEBUG, SLUB does not maintain the number of slabs
allocated per node for a kmem_cache. Thus, slabs_node() in
__kmem_cache_empty() will always return 0. So, in such situation, it is
required to check per-cpu slabs to make sure if a kmem_cache is empty or
not.
Please note that __kmem_cache_shutdown() and __kmem_cache_shrink() are not
affected by !CONFIG_SLUB_DEBUG as they call flush_all() to clear per-cpu
slabs.
Link: http://lkml.kernel.org/r/20180619213352.71740-1-shakeelb@xxxxxxxxxx
Link: http://lkml.kernel.org/r/CAHmME9rtoPwxUSnktxzKso14iuVCWT7BE_-_8PAC=pGw1iJnQg@xxxxxxxxxxxxxx
Fixes: f9e13c0a5a33 ("slab, slub: skip unnecessary kasan_cache_shutdown()")
Signed-off-by: Shakeel Butt <shakeelb@xxxxxxxxxx>
Reported-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Tested-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
Cc: Christoph Lameter <cl@xxxxxxxxx>
Cc: Pekka Enberg <penberg@xxxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/slub.c | 16 +++++++++++++++-
1 file changed, 15 insertions(+), 1 deletion(-)
diff -puN mm/slub.c~slub-fix-__kmem_cache_empty-for-config_slub_debug mm/slub.c
--- a/mm/slub.c~slub-fix-__kmem_cache_empty-for-config_slub_debug
+++ a/mm/slub.c
@@ -3673,9 +3673,23 @@ static void free_partial(struct kmem_cac
bool __kmem_cache_empty(struct kmem_cache *s)
{
- int node;
+ int cpu, node;
struct kmem_cache_node *n;
+ /*
+ * slabs_node will always be 0 for !CONFIG_SLUB_DEBUG. So, manually
+ * check slabs for all cpus.
+ */
+ if (!IS_ENABLED(CONFIG_SLUB_DEBUG)) {
+ for_each_online_cpu(cpu) {
+ struct kmem_cache_cpu *c;
+
+ c = per_cpu_ptr(s->cpu_slab, cpu);
+ if (c->page || slub_percpu_partial(c))
+ return false;
+ }
+ }
+
for_each_kmem_cache_node(s, node, n)
if (n->nr_partial || slabs_node(s, node))
return false;
_
Patches currently in -mm which might be from shakeelb@xxxxxxxxxx are
slub-fix-__kmem_cache_empty-for-config_slub_debug.patch
