From: David Rientjes <rientjes@google.com>
To: Karl Mehltretter <kmehltretter@gmail.com>
Cc: Vlastimil Babka <vbabka@kernel.org>, Harry Yoo <harry@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Hao Li <hao.li@linux.dev>, Christoph Lameter <cl@gentwo.org>,
Roman Gushchin <roman.gushchin@linux.dev>,
Shengming Hu <hu.shengming@zte.com.cn>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/slub: initialize the free pointer of the bootstrap kmem_cache_node
Date: Fri, 16 Oct 2026 15:35:48 -0700 (PDT) [thread overview]
Message-ID: <3284bb03-6c23-611c-872c-19954a7f3381@google.com> (raw)
In-Reply-To: <20261010203906.93156-1-kmehltretter@gmail.com>
On Sat, 10 Oct 2026, Karl Mehltretter wrote:
> With slub_debug=FZPU, validating kmem_cache_node reports
>
> BUG kmem_cache_node (Not tainted): Freepointer corrupt
> Object 0xffff888000140040 @offset=64 fp=0x5a5a5a5a5a5a5a5a
>
> and taints the kernel. Poisoning places the bootstrap object's free
> pointer outside the object, where check_object() checks it even while
> allocated.
>
> early_kmem_cache_node_alloc() previously took this object from a
> freelist with an initialized pointer. It now takes it from the slab
> iterator and builds the freelist only for the remaining objects,
> leaving its pointer filled with POISON_INUSE.
>
> Initialize the bootstrap object's free pointer to NULL.
>
> Fixes: dc795d4c0282 ("mm/slub: defer freelist construction until after bulk allocation from a new slab")
> Assisted-by: LLM
> Signed-off-by: Karl Mehltretter <kmehltretter@gmail.com>
Tested-by: David Rientjes <rientjes@google.com>
prev parent reply other threads:[~2026-10-16 22:35 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-10 20:39 Karl Mehltretter
2026-10-15 16:18 ` Harry Yoo
2026-10-15 16:31 ` Harry Yoo (Meta)
2026-10-15 16:47 ` Vlastimil Babka (SUSE)
2026-10-16 1:24 ` hu.shengming
2026-10-16 22:35 ` David Rientjes [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=3284bb03-6c23-611c-872c-19954a7f3381@google.com \
--to=rientjes@google.com \
--cc=akpm@linux-foundation.org \
--cc=cl@gentwo.org \
--cc=hao.li@linux.dev \
--cc=harry@kernel.org \
--cc=hu.shengming@zte.com.cn \
--cc=kmehltretter@gmail.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=roman.gushchin@linux.dev \
--cc=vbabka@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®