From: Vlastimil Babka <vbabka@suse.cz>
To: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@linux.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
kernel-team@android.com, vinmenon@codeaurora.org,
Kees Cook <keescook@chromium.org>,
Matthew Garrett <mjg59@google.com>, Roman Gushchin <guro@fb.com>,
Vlastimil Babka <vbabka@suse.cz>, Jann Horn <jannh@google.com>,
Vijayanand Jitta <vjitta@codeaurora.org>
Subject: [PATCH 6/9] mm, slub: introduce static key for slub_debug()
Date: Wed, 10 Jun 2020 18:31:32 +0200 [thread overview]
Message-ID: <20200610163135.17364-7-vbabka@suse.cz> (raw)
In-Reply-To: <20200610163135.17364-1-vbabka@suse.cz>
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>
---
mm/slub.c | 16 +++++++++++++---
1 file changed, 13 insertions(+), 3 deletions(-)
diff --git a/mm/slub.c b/mm/slub.c
index 8dd2925448ae..24d3e5f832aa 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))
--
2.26.2
next prev parent reply other threads:[~2020-06-10 16:32 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-10 16:31 [PATCH 0/9] slub_debug fixes and improvements Vlastimil Babka
2020-06-10 16:31 ` [PATCH 1/9] mm, slub: extend slub_debug syntax for multiple blocks Vlastimil Babka
2020-06-10 16:31 ` [PATCH 2/9] mm, slub: make some slub_debug related attributes read-only Vlastimil Babka
2020-06-10 16:31 ` [PATCH 3/9] mm, slub: remove runtime allocation order changes Vlastimil Babka
2020-06-10 16:31 ` [PATCH 4/9] mm, slub: make remaining slub_debug related attributes read-only Vlastimil Babka
2020-06-10 16:31 ` [PATCH 5/9] mm, slub: make reclaim_account attribute read-only Vlastimil Babka
2020-06-10 16:31 ` Vlastimil Babka [this message]
2020-06-10 21:59 ` [PATCH 6/9] mm, slub: introduce static key for slub_debug() Roman Gushchin
2020-06-17 17:54 ` Kees Cook
2020-06-10 16:31 ` [PATCH 7/9] mm, slub: introduce kmem_cache_debug_flags() Vlastimil Babka
2020-06-10 22:06 ` Roman Gushchin
2020-06-17 17:56 ` Kees Cook
2020-06-18 8:32 ` Vlastimil Babka
2020-06-18 8:37 ` Vlastimil Babka
2020-06-18 19:54 ` Roman Gushchin
2020-06-18 19:56 ` Kees Cook
2020-06-10 16:31 ` [PATCH 8/9] mm, slub: extend checks guarded by slub_debug static key Vlastimil Babka
2020-06-10 22:09 ` Roman Gushchin
2020-06-10 16:31 ` [PATCH 9/9] mm, slab/slub: move and improve cache_from_obj() Vlastimil Babka
2020-06-10 22:46 ` Roman Gushchin
2020-06-11 9:56 ` Vlastimil Babka
2020-06-11 20:04 ` Roman Gushchin
2020-06-17 17:49 ` Kees Cook
2020-06-18 10:10 ` Vlastimil Babka
2020-06-18 19:59 ` Kees Cook
2020-06-18 20:05 ` Roman Gushchin
2020-06-19 19:02 ` Kees Cook
2020-06-24 7:57 ` Vlastimil Babka
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