From mboxrd@z Thu Jan 1 00:00:00 1970 From: richard@nod.at (Richard Weinberger) Date: Wed, 29 Jan 2014 08:17:35 +0100 Subject: [BUG] reproducable ubifs reboot assert and corruption In-Reply-To: <20140129053238.GA6035@gmail.com> References: <20140122051510.GB17284@gmail.com> <20140127163939.GA27809@gmail.com> <20140129053238.GA6035@gmail.com> Message-ID: <52E8AB0F.2090905@nod.at> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org Am 29.01.2014 06:32, schrieb Andrew Ruder: > Ok, I've got some more useful information. I have been adding > a multitude of WARN_ON's and prink's all over the remount code and have > come up with the attached log. > > A little bit of explanation: > > Line 1: sync_filesystem (from do_remount_sb) > Line 188: sync_filesystem ends > Line 43, 64, 81, 98, 114, 135, 156, 173: write operations that occur > during sync_filesystem. Before each warning I print the inode pointer. > Line 197: read-only remount has completely finished (this message is > from userspace post remount) > Line 199: a sync is called, there are apparently dirty inodes in our > now-readonly ubifs filesystem > Line 215: failed assert that occurs because the writeback triggers for > inode 0xd75b9450 (see line 41, it got in with a sys_write while we were > running our sync_filesystem in do_remount_sb) > > Does this help? It looks like there is a race condition between the > writeback code and the remount read-only. Nothing is done to lock out > writes during the first half of the do_remount_sb and some stuff makes > it into the writeback worker queue while we are busy syncing the > filesystem only to trigger later when ubifs has decided it is > read-only... So you can trigger this by running fsstress on /mnt and then call mount -o remount,ro /mnt? Can you also trigger it on nandsim or mtdram? I did a quick test on my testbed using mtdram and was unable to trigger it. But I fear my box is too fast. Thanks, //richard