diff options
| author | Vlastimil Babka | 2020-08-06 23:18:51 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2020-08-07 11:33:22 -0700 |
| commit | ca0cab65ea2b8c1527dc48c8dfd38ae055f5f241 (patch) | |
| tree | 83b70975ae67204d8c10617eb80790e5aa2cd600 | |
| parent | 8f58119ac49c03c5a0879353661c586b0436c250 (diff) | |
mm, slub: introduce static key for slub_debug()
One advantage of CONFIG_SLUB_DEBUG is that a generic distro kernel can be
built with the option enabled, but it's inactive until simply enabled on
boot, without rebuilding the kernel. With a static key, we can further
eliminate the overhead of checking whether a cache has a particular debug
flag enabled if we know that there are no such caches (slub_debug was not
enabled during boot). We use the same mechanism also for e.g.
page_owner, debug_pagealloc or kmemcg functionality.
This patch introduces the static key and makes the general check for
per-cache debug flags kmem_cache_debug() use it. This benefits several
call sites, including (slow path but still rather frequent) __slab_free().
The next patches will add more uses.
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Kees Cook <keescook@chromium.org>
Acked-by: Roman Gushchin <guro@fb.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Jann Horn <jannh@google.com>
Cc: Vijayanand Jitta <vjitta@codeaurora.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Pekka Enberg <penberg@kernel.org>
Link: http://lkml.kernel.org/r/20200610163135.17364-7-vbabka@suse.cz
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/slub.c | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/mm/slub.c b/mm/slub.c index 617cf1fff128..8adab4c5296d 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -114,13 +114,21 @@ * the fast path and disables lockless freelists. */ +#ifdef CONFIG_SLUB_DEBUG +#ifdef CONFIG_SLUB_DEBUG_ON +DEFINE_STATIC_KEY_TRUE(slub_debug_enabled); +#else +DEFINE_STATIC_KEY_FALSE(slub_debug_enabled); +#endif +#endif + static inline int kmem_cache_debug(struct kmem_cache *s) { #ifdef CONFIG_SLUB_DEBUG - return unlikely(s->flags & SLAB_DEBUG_FLAGS); -#else - return 0; + if (static_branch_unlikely(&slub_debug_enabled)) + return s->flags & SLAB_DEBUG_FLAGS; #endif + return 0; } void *fixup_red_left(struct kmem_cache *s, void *p) @@ -1389,6 +1397,8 @@ static int __init setup_slub_debug(char *str) slub_debug_string = saved_str; } out: + if (slub_debug != 0 || slub_debug_string) + static_branch_enable(&slub_debug_enabled); if ((static_branch_unlikely(&init_on_alloc) || static_branch_unlikely(&init_on_free)) && (slub_debug & SLAB_POISON)) |