From: Christoph Hellwig <hch@lst.de>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Christoph Lameter <cl@gentwo.org>,
David Rientjes <rientjes@google.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Harry Yoo <harry.yoo@oracle.com>, Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org,
kernel test robot <oliver.sang@intel.com>,
Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH] mm/mempool: fix poisoning order>0 pages with HIGHMEM
Date: Fri, 14 Nov 2025 06:04:10 +0100 [thread overview]
Message-ID: <20251114050410.GA26404@lst.de> (raw)
In-Reply-To: <20251113-mempool-poison-v1-1-233b3ef984c3@suse.cz>
On Thu, Nov 13, 2025 at 07:54:35PM +0100, Vlastimil Babka wrote:
> Christoph found out this is due to the poisoning code not dealing
> properly with CONFIG_HIGHMEM because only the first page is mapped but
> then the whole potentially high-order page is accessed.
>
> This went unnoticed for years probably because nobody has yet used a
> mempool for order>0 pages before the new block code in -next.
I did a quick audit: and bcache, dm-integrity (config dependent) and the
KASAN unit tests create page based mempools with order > 0. It looks
like none of those ever got much testing on highmem systems.
The fix looks good:
Reviewed-by: Christoph Hellwig <hch@lst.de>
next prev parent reply other threads:[~2025-11-14 5:04 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-13 18:54 Vlastimil Babka
2025-11-14 5:04 ` Christoph Hellwig [this message]
2025-11-14 16:51 ` Vlastimil Babka
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