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From: Kees Cook <keescook@chromium.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: 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>,
	linux-mm@kvack.org, linux-kernel@vger.kernel.org,
	kernel-team@android.com, vinmenon@codeaurora.org,
	Matthew Garrett <mjg59@google.com>, Roman Gushchin <guro@fb.com>,
	Jann Horn <jannh@google.com>,
	Vijayanand Jitta <vjitta@codeaurora.org>
Subject: Re: [PATCH 6/9] mm, slub: introduce static key for slub_debug()
Date: Wed, 17 Jun 2020 10:54:07 -0700	[thread overview]
Message-ID: <202006171050.D48F4B7@keescook> (raw)
In-Reply-To: <20200610163135.17364-7-vbabka@suse.cz>

On Wed, Jun 10, 2020 at 06:31:32PM +0200, Vlastimil Babka wrote:
> 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

Yet another potential future user of DEFINE_STATIC_KEY_MAYBE()[1], once
I get it landed. :)

Reviewed-by: Kees Cook <keescook@chromium.org>

[1] https://lore.kernel.org/lkml/20200324203231.64324-2-keescook@chromium.org/

-- 
Kees Cook

  parent reply	other threads:[~2020-06-17 17:54 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 ` [PATCH 6/9] mm, slub: introduce static key for slub_debug() Vlastimil Babka
2020-06-10 21:59   ` Roman Gushchin
2020-06-17 17:54   ` Kees Cook [this message]
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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