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From: Gabriel Ryan <gabe@cs.columbia.edu>
To: Matthew Wilcox <willy@infradead.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-fsdevel@vger.kernel.org, linux-mm@kvack.org
Subject: Race in mm/readahead.c:140 file_ra_state_init / block/ioctl.c:497 blkdev_common_ioctl
Date: Wed, 17 Jan 2024 15:08:47 -0500	[thread overview]
Message-ID: <CALbthtcbD1bDYrQC6iNk6rMgBXO8LvH0kqxFh3=0nUdqm35Lsg@mail.gmail.com> (raw)

Hi,

We found a race in the mm subsystem in kernel version v5.18-rc5 that
appears to be potentially harmful using a race testing tool we are
developing. The race occurs between:

mm/readahead.c:140 file_ra_state_init

    ra->ra_pages = inode_to_bdi(mapping->host)->ra_pages;

block/ioctl.c:497 blkdev_common_ioctl

    bdev->bd_disk->bdi->ra_pages = (arg * 512) / PAGE_SIZE;


which both set the ra->ra_pages value. It appears this race could lead
to undefined behavior, if multiple threads set ra->ra_pages to
different values simultaneously for a single file inode.

Best,
Gabe


             reply	other threads:[~2024-01-17 20:08 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-01-17 20:08 Gabriel Ryan [this message]
2024-01-17 20:38 ` Matthew Wilcox
2024-01-17 21:02   ` Gabriel Ryan

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