From: Vlastimil Babka <vbabka@suse.cz>
To: Imran Khan <imran.f.khan@oracle.com>,
glider@google.com, elver@google.com, dvyukov@google.com,
cl@linux.com, penberg@kernel.org, rientjes@google.com,
iamjoonsoo.kim@lge.com, akpm@linux-foundation.org,
roman.gushchin@linux.dev, 42.hyeyoo@gmail.com
Cc: linux-kernel@vger.kernel.org, kasan-dev@googlegroups.com,
linux-mm@kvack.org
Subject: Re: [PATCH v2] Introduce sysfs interface to disable kfence for selected slabs.
Date: Fri, 12 Aug 2022 12:28:53 +0200 [thread overview]
Message-ID: <c60897e7-fa5d-a1a9-09a6-c80cfe4b5fd5@suse.cz> (raw)
In-Reply-To: <20220811085938.2506536-1-imran.f.khan@oracle.com>
On 8/11/22 10:59, Imran Khan wrote:
> By default kfence allocation can happen for any slab object, whose size
> is up to PAGE_SIZE, as long as that allocation is the first allocation
> after expiration of kfence sample interval. But in certain debugging
> scenarios we may be interested in debugging corruptions involving
> some specific slub objects like dentry or ext4_* etc. In such cases
> limiting kfence for allocations involving only specific slub objects
> will increase the probablity of catching the issue since kfence pool
> will not be consumed by other slab objects.
>
> This patch introduces a sysfs interface '/sys/kernel/slab/<name>/skip_kfence'
> to disable kfence for specific slabs. Having the interface work in this
> way does not impact current/default behavior of kfence and allows us to
> use kfence for specific slabs (when needed) as well. The decision to
> skip/use kfence is taken depending on whether kmem_cache.flags has
> (newly introduced) SLAB_SKIP_KFENCE flag set or not.
>
> Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Nit below:
> ---
>
> Changes since v1:
> - Remove RFC tag
>
> include/linux/slab.h | 6 ++++++
> mm/kfence/core.c | 7 +++++++
> mm/slub.c | 27 +++++++++++++++++++++++++++
> 3 files changed, 40 insertions(+)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 0fefdf528e0d..947d912fd08c 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -119,6 +119,12 @@
> */
> #define SLAB_NO_USER_FLAGS ((slab_flags_t __force)0x10000000U)
>
> +#ifdef CONFIG_KFENCE
> +#define SLAB_SKIP_KFENCE ((slab_flags_t __force)0x20000000U)
> +#else
> +#define SLAB_SKIP_KFENCE 0
> +#endif
The whitespace here (spaces) differs from other flags above (tabs).
prev parent reply other threads:[~2022-08-12 10:28 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-11 8:59 [PATCH v2] Introduce sysfs interface to disable kfence for selected slabs Imran Khan
2022-08-11 9:31 ` vbabka
2022-08-11 9:52 ` Marco Elver
2022-08-11 10:07 ` vbabka
2022-08-11 13:21 ` Marco Elver
2022-08-11 15:10 ` Imran Khan
2022-08-12 9:11 ` Marco Elver
2022-08-11 10:40 ` Hyeonggon Yoo
2022-08-12 10:28 ` Vlastimil Babka [this message]
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