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From: Gong Ruiqi <gongruiqi1@huawei.com>
To: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
	<linux-hardening@vger.kernel.org>,
	Alexander Lobakin <aleksander.lobakin@intel.com>,
	<kasan-dev@googlegroups.com>,
	Wang Weiyang <wangweiyang2@huawei.com>,
	Xiu Jianfeng <xiujianfeng@huawei.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Christoph Lameter <cl@linux.com>,
	David Rientjes <rientjes@google.com>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Pekka Enberg <penberg@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Paul Moore <paul@paul-moore.com>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	"Gustavo A. R. Silva" <gustavoars@kernel.org>,
	"GONG, Ruiqi" <gongruiqi@huaweicloud.com>
Subject: Re: [PATCH RFC v2] Randomized slab caches for kmalloc()
Date: Mon, 22 May 2023 15:35:02 +0800	[thread overview]
Message-ID: <19707cc6-fa5e-9835-f709-bc8568e4c9cd@huawei.com> (raw)
In-Reply-To: <CAB=+i9R0GZiau7PKDSGdCOijPH1TVqA3rJ5tQLejJpoR55h6dg@mail.gmail.com>



On 2023/05/17 6:35, Hyeonggon Yoo wrote:
> [Resending this email after noticing I did not reply-to-all]
> 
> On Fri, May 12, 2023 at 7:11 PM Gong Ruiqi <gongruiqi1@huawei.com> wrote:
>>

[...]

> 
>>>> +#ifdef CONFIG_RANDOM_KMALLOC_CACHES
>>>> +# define SLAB_RANDOMSLAB       ((slab_flags_t __force)0x01000000U)
>>>> +#else
>>>> +# define SLAB_RANDOMSLAB       0
>>>> +#endif
> 
> There is already the SLAB_KMALLOC flag that indicates if a cache is a
> kmalloc cache. I think that would be enough for preventing merging
> kmalloc caches?

After digging into the code of slab merging (e.g. slab_unmergeable(),
find_mergeable(), SLAB_NEVER_MERGE, SLAB_MERGE_SAME etc), I haven't
found an existing mechanism that prevents normal kmalloc caches with
SLAB_KMALLOC from being merged with other slab caches. Maybe I missed
something?

While SLAB_RANDOMSLAB, unlike SLAB_KMALLOC, is added into
SLAB_NEVER_MERGE, which explicitly indicates the no-merge policy.


  reply	other threads:[~2023-05-22  7:35 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-05-08  7:55 GONG, Ruiqi
2023-05-10 18:43 ` Hyeonggon Yoo
2023-05-10 19:32   ` Pedro Falcato
2023-05-12 10:11   ` Gong Ruiqi
2023-05-14  9:30     ` Vlastimil Babka
2023-05-15  8:20       ` Gong Ruiqi
2023-05-16 22:35     ` Hyeonggon Yoo
2023-05-22  7:35       ` Gong Ruiqi [this message]
2023-05-22  8:03         ` Hyeonggon Yoo
2023-05-22  8:58           ` GONG, Ruiqi
2023-05-24  5:54             ` Hyeonggon Yoo
2023-05-31  3:47               ` GONG, Ruiqi
2023-05-11 12:30 ` xiujianfeng
2023-05-11 14:54 ` Alexander Lobakin
2023-05-15  6:26   ` Gong Ruiqi
2023-05-16 12:43     ` Alexander Lobakin
2023-05-16 19:34 ` Kees Cook
2023-05-31  7:59   ` Gong Ruiqi

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