| From b6053f7a8300ec89984740a13fbcf0668eb4977f Mon Sep 17 00:00:00 2001 |
| From: Sasha Levin <sashal@kernel.org> |
| Date: Thu, 29 Apr 2021 22:54:42 -0700 |
| Subject: mm, slub: enable slub_debug static key when creating cache with |
| explicit debug flags |
| |
| From: Vlastimil Babka <vbabka@suse.cz> |
| |
| [ Upstream commit 1f0723a4c0df36cbdffc6fac82cd3c5d57e06d66 ] |
| |
| Commit ca0cab65ea2b ("mm, slub: introduce static key for slub_debug()") |
| introduced a static key to optimize the case where no debugging is |
| enabled for any cache. The static key is enabled when slub_debug boot |
| parameter is passed, or CONFIG_SLUB_DEBUG_ON enabled. |
| |
| However, some caches might be created with one or more debugging flags |
| explicitly passed to kmem_cache_create(), and the commit missed this. |
| Thus the debugging functionality would not be actually performed for |
| these caches unless the static key gets enabled by boot param or config. |
| |
| This patch fixes it by checking for debugging flags passed to |
| kmem_cache_create() and enabling the static key accordingly. |
| |
| Note such explicit debugging flags should not be used outside of |
| debugging and testing as they will now enable the static key globally. |
| btrfs_init_cachep() creates a cache with SLAB_RED_ZONE but that's a |
| mistake that's being corrected [1]. rcu_torture_stats() creates a cache |
| with SLAB_STORE_USER, but that is a testing module so it's OK and will |
| start working as intended after this patch. |
| |
| Also note that in case of backports to kernels before v5.12 that don't |
| have 59450bbc12be ("mm, slab, slub: stop taking cpu hotplug lock"), |
| static_branch_enable_cpuslocked() should be used. |
| |
| [1] https://lore.kernel.org/linux-btrfs/20210315141824.26099-1-dsterba@suse.com/ |
| |
| Link: https://lkml.kernel.org/r/20210315153415.24404-1-vbabka@suse.cz |
| Fixes: ca0cab65ea2b ("mm, slub: introduce static key for slub_debug()") |
| Signed-off-by: Vlastimil Babka <vbabka@suse.cz> |
| Reported-by: Oliver Glitta <glittao@gmail.com> |
| Acked-by: David Rientjes <rientjes@google.com> |
| Cc: Christoph Lameter <cl@linux.com> |
| Cc: Pekka Enberg <penberg@kernel.org> |
| Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> |
| Cc: "Paul E. McKenney" <paulmck@kernel.org> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Sasha Levin <sashal@kernel.org> |
| --- |
| mm/slub.c | 9 +++++++++ |
| 1 file changed, 9 insertions(+) |
| |
| diff --git a/mm/slub.c b/mm/slub.c |
| index 3021ce9bf1b3..0fa68cfa648b 100644 |
| --- a/mm/slub.c |
| +++ b/mm/slub.c |
| @@ -3827,6 +3827,15 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order) |
| |
| static int kmem_cache_open(struct kmem_cache *s, slab_flags_t flags) |
| { |
| +#ifdef CONFIG_SLUB_DEBUG |
| + /* |
| + * If no slub_debug was enabled globally, the static key is not yet |
| + * enabled by setup_slub_debug(). Enable it if the cache is being |
| + * created with any of the debugging flags passed explicitly. |
| + */ |
| + if (flags & SLAB_DEBUG_FLAGS) |
| + static_branch_enable(&slub_debug_enabled); |
| +#endif |
| s->flags = kmem_cache_flags(s->size, flags, s->name); |
| #ifdef CONFIG_SLAB_FREELIST_HARDENED |
| s->random = get_random_long(); |
| -- |
| 2.30.2 |
| |