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[172.10.233.147]) by smtp.gmail.com with ESMTPSA id f4sm1327545qkp.14.2022.01.08.09.12.09 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 08 Jan 2022 09:12:09 -0800 (PST) Date: Sat, 8 Jan 2022 09:12:08 -0800 (PST) From: Hugh Dickins X-X-Sender: hugh@ripple.anvils To: Matthew Wilcox cc: Hugh Dickins , Andrew Morton , Christoph Hellwig , Jan Kara , William Kucharski , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH next 2/3] shmem: Fix data loss when folio truncated In-Reply-To: Message-ID: <54faec38-f3f9-a326-65e2-cba91a40ccca@google.com> References: <24d53dac-d58d-6bb9-82af-c472922e4a31@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Authentication-Results: imf29.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=pb+PQxSx; dmarc=pass (policy=reject) header.from=google.com; spf=pass (imf29.hostedemail.com: domain of hughd@google.com designates 209.85.222.182 as permitted sender) smtp.mailfrom=hughd@google.com X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 8A203120004 X-Stat-Signature: 4rqeuajqoy36ge648z8ze1j8sf5oiu6p X-HE-Tag: 1641661931-667630 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: On Fri, 7 Jan 2022, Matthew Wilcox wrote: > On Sun, Jan 02, 2022 at 05:34:05PM -0800, Hugh Dickins wrote: > > xfstests generic 098 214 263 286 412 used to pass on huge tmpfs (well, > > three of those _require_odirect, enabled by a shmem_direct_IO() stub), > > but still fail even with the partial_end fix. > > > > generic/098 output mismatch shows actual data loss: > > --- tests/generic/098.out > > +++ /home/hughd/xfstests/results//generic/098.out.bad > > @@ -4,9 +4,7 @@ > > wrote 32768/32768 bytes at offset 262144 > > XXX Bytes, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) > > File content after remount: > > -0000000 aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa aa > > -* > > -0400000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > +0000000 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 > > ... > > generic/098 is passing for me ;-( I'm using 'always' for THPs. > I'll have to try harder. Regardless, I think your fix is good ... Worrying that the test behaves differently. Your 'always': you have '-o huge=always' in the exported TMPFS_MOUNT_OPTIONS? That should be enough, but I admit to belt and braces by also echo force > /sys/kernel/mm/transparent_hugepage/shmem_enabled Hugh I also back up with