On 5/12/21 5:35 PM, Vlastimil Babka wrote: > On 5/12/21 4:50 PM, Greg Kroah-Hartman wrote: >> 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. Geez, and this part was also missed. Also why I chose not to Cc stable in the first place. >> [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> > > Uh, rather not release this to stable without the followup fix: > https://lore.kernel.org/linux-mm/20210504120019.26791-1-vbabka@suse.cz/ > >> --- >> mm/slub.c | 9 +++++++++ >> 1 file changed, 9 insertions(+) >> >> diff --git a/mm/slub.c b/mm/slub.c >> index 05a501b67cd5..e4f7978d43c2 100644 >> --- a/mm/slub.c >> +++ b/mm/slub.c >> @@ -3779,6 +3779,15 @@ 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(); >> >
diff --git a/mm/slub.c b/mm/slub.c index 05a501b67cd5..e4f7978d43c2 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3779,6 +3779,15 @@ 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();