On Fri, Oct 16, 2009 at 12:28:18AM -0400, Parag Warudkar wrote: > So I have been experimenting with various root file systems on my > laptop running latest git. This laptop some times has problems waking > up from sleep and that results in it needing a hard reset and > subsequently unclean file system. A number of people have reported this, and there is some discussion and some suggestions that I've made here: http://bugzilla.kernel.org/show_bug.cgi?id=14354 It's been very frustrating because I have not been able to replicate it myself; I've been very much looking for someone who is (a) willing to work with me on this, and perhaps willing to risk running fsck frequently, perhaps after every single unclean shutdown, and (b) who can reliably reproduce this problem. On my system, which is a T400 running 9.04 with the latest git kernels, I've not been able to reproduce it, despite many efforts to try to reproduce it. (i.e., suspend the machine and then pull the battery and power; pulling the battery and power, "echo c > /proc/sysrq-trigger", etc., while doing "make -j4" when the system is being uncleanly shutdown) So if you can come up with a reliable reproduction case, and don't mind doing some experiments and/or exchanging debugging correspondance with me, please let me know. I'd **really** appreciate the help. Information that would be helpful to me would be: a) Detailed hardware information (what type of disk/SSD, what type of laptop, hardware configuration, etc.) b) Detailed software information (what version of the kernel are you using including any special patches, what distro and version are you using, are you using LVM or dm-crypt, what partition or partitions did you have mounted, was the failing partition a root partition or some other mounted partition, etc.) c) Detailed reproduction recipe (what programs were you running before the crash/failed suspend/resume, etc.) If you do decide to go hunting this problem, one thing I would strongly suggest is that either to use "tune2fs -c 1 /dev/XXX" to force a fsck after every reboot, or if you are using LVM, to use the e2croncheck script (found as an attachment in the above bugzilla entry or in the e2fsprogs sources in the contrib directory) to take a snapshot and then check the snapshot right after you reboot and login to your system. The reported file system corruptions seem to involve the block allocation bitmaps getting corrupted, and so you will significantly reduce the chances of data loss if you run e2fsck as soon as possible after the file system corruption happens. This helps you not lose data, and it also helps us find the bug, since it helps pinpoint the earliest possible point where the file system is getting corrupted. (I suspect that some bug reporters had their file system get corrupted one or more boot sessions earlier, and by the time the corruption was painfully obvious, they had lost data. Mercifully, running fsck frequently is much less painful on a freshly created ext4 filesystem, and of course if you are using an SSD.) If you can reliably reproduce the problem, it would be great to get a bisection, or at least a confirmation that the problem doesn't exist on 2.6.31, but does exist on 2.6.32-rcX kernels. At this point I'm reasonably sure it's a post-2.6.31 regression, but it would be good to get a hard confirmation of that fact. For people with a reliable reproduction case, one possible experiment can be found here: http://bugzilla.kernel.org/show_bug.cgi?id=14354#c18 Another thing you might try is to try reverting these commits one at a time, and see if they make the problem go away: d0646f7, 5534fb5, 7178057. These are three commits that seem most likely, but there are only 93 ext4-related commits, so doing a "git bisect start v2.6.31 v2.6.32-rc5 -- fs/ext4 fs/jbd2" should only take at most seven compile tests --- assuming this is indeed a 2.6.31 regression and the problem is an ext4-specific code change, as opposed to some other recent change in the writeback code or some device driver which is interacting badly with ext4. If that assumption isn't true and so a git bisect limited to fs/ext4 and fs/jbd2 doesn't find a bad commit which when reverted makes the problem go away, we could try a full bisection search via "git bisect start v2.6.31 v2.6.31-rc3", which would take approximately 14 compile tests, but hopefully that wouldn't be necessary. I'm going to be at the kernel summit in Tokyo next week, so my e-mail latency will be a bit longer than normal, which is one of the reason why I've left a goodly list of potential experiments for people to try. If you can come up with a reliable regression, and are willing to work with me or to try some of the above mentioned tests, I'll definitely buy you a real (or virtual) beer. Given that a number of people have reported losing data as a result, it would **definitely** be a good thing to get this fixed before 2.6.32 is released. Thanks, - Ted -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
