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Mon, 10 Mar 2025 09:54:46 -0700 (PDT) From: Yuan Tan To: axboe@kernel.dk, syzbot+f2aaf773187f5cae54f3@syzkaller.appspotmail.com Cc: linux-block@vger.kernel.org, akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, willy@infradead.org, falcon@tinylab.org, tanyuan@tinylab.org Subject: [PATCH] block: add lock for safe nrpages access in invalidate_bdev() Date: Mon, 10 Mar 2025 09:54:00 -0700 Message-Id: <20250310165400.3166618-1-tanyuan@tinylab.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <67ceb38a.050a0220.e1a89.04b1.GAE@google.com> References: <67ceb38a.050a0220.e1a89.04b1.GAE@google.com> MIME-Version: 1.0 X-Stat-Signature: i9hwys5fnikr9r4jmnn3x8rw1zef364t X-Rspam-User: X-Rspamd-Queue-Id: 7DFAA1C000C X-Rspamd-Server: rspam01 X-HE-Tag: 1741625760-341491 X-HE-Meta: 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 +bUF7EKP NrlC1Li2HgdK6TKq1ok/uDqvEpyw0ds1o8nYckCHx6c7IOCwLOyg/AEBReSL+e1ames997SU+8q+paLgHv1omw4aacuwQ7AhD31jptB16AKJI4ZLE0zQJq/WS8jM0CN4hWw+9NWKiCagKxJYf66Mln7OYnN3TFFVPDp7xy7TfaebCzRgBQu2m0mY0xmzv1hGcK15qiiSSMO/ELv9RYrGpqjrecJsOc5uVVpus8HLm3cwAUCJreU14yq9XPlE+ahUZnsMyHBYtHR70ZGLPNyWYZyCqZOn8d8SKGCyEV6+97UFFZ4X5M5QNdLnt1GiDTbYI4b7S2zfaYh8IUkQWap2F7y0k1B6KfdCrkGInkxHTmIIj4MA7UYq+kbS/Ko7/GbV6dZSFZ+gfGevvTUPOIsU11e7+YMixFGYMRkB30JU6vtU4jrDtdkpp8Iu1e07FZvFgB11O9HmdGKq13ZpJzhQOhnUeB9OsonfYaT0sAE7YuRo+1Wmu29ldpuhBNqcCs/unBxh5Dg23fwOvbdI= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Syzbot reported a data-race in __filemap_add_folio / invalidate_bdev[1] due to concurrent access to mapping->nrpages. Adds a lock around the access to nrpages. [1] https://syzkaller.appspot.com/bug?extid=f2aaf773187f5cae54f3 Signed-off-by: Yuan Tan Reported-by: syzbot+f2aaf773187f5cae54f3@syzkaller.appspotmail.com --- block/bdev.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) I had already completed and tested this patch before Matthew sent the email. I'm not sure if this solution is correct. If it's not, please ignore the patch :) diff --git a/block/bdev.c b/block/bdev.c index 9d73a8fbf7f9..934043d09068 100644 --- a/block/bdev.c +++ b/block/bdev.c @@ -96,7 +96,14 @@ void invalidate_bdev(struct block_device *bdev) { struct address_space *mapping = bdev->bd_mapping; - if (mapping->nrpages) { + XA_STATE(xas, &mapping->i_pages, 0); /* we don't care about the index */ + unsigned long nrpages; + + xas_lock_irq(&xas); + nrpages = mapping->nrpages; + xas_unlock_irq(&xas); + + if (nrpages) { invalidate_bh_lrus(); lru_add_drain_all(); /* make sure all lru add caches are flushed */ invalidate_mapping_pages(mapping, 0, -1);