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Received: from willy by casper.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rTR2U-0000000EUM5-3YYE; Fri, 26 Jan 2024 18:34:55 +0000 Date: Fri, 26 Jan 2024 18:34:54 +0000 From: Matthew Wilcox To: Chenyuan Yang Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, syzkaller@googlegroups.com, Zijie Zhao , John Hubbard Subject: Re: [Linux Kernel Bug][mm/gup] 3 Warning Crashes: kmalloc bug in gup_test_ioctl, is_valid_gup_args, pin_user_pages_fast Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Queue-Id: EBC84140018 X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: hytbusxruz45c5xbj3iexrtt1odja5ia X-HE-Tag: 1706294097-906571 X-HE-Meta: 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 tj3/kM7Q 0/oUqsOwdkCXw5SzdQcJHHOq/dgB32nymabMBySJVSb1hAl8R95Mf4Lu3T5Y2mLbUdquHlUWXckvNrBDm2QZvdU/YgorvLNxz3d4E0GJyKU4CQjuuNcd2gVAGTG5BzBDzfmuFatLGgEJZrzJyex32h4vKLrNaTjatKiZ4cTrl68BpPdfxUjDw7mbkRYEWAa0mYWI1ySR1cH2oDJg= 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: On Fri, Jan 26, 2024 at 11:31:26AM -0600, Chenyuan Yang wrote: > In this context, I would like to seek your valued opinion. Do you > believe it would be more prudent to avoid fuzz testing the > `gup_test_ioctl`, or are the warnings in `gup_test_ioctl` an > anticipated outcome? It seems like a waste of time. Debian certainly disables it, so unless you can find a distro who enables it, I wouldn't bother. > It seems that `gup_test_ioctl` can indeed be exposed in the kernel by > accessing /sys/kernel/debug/gup_test. If someone wants to fix these things, they can, but it just doesn't seem worth doing. Part of the art of fuzz testing is finding things that are worth testing.