2014-07-02 12:17 GMT+02:00 David Jander <david@xxxxxxxxxxx>: > > Hi Eric, > > On Tue, 1 Jul 2014 12:36:46 -0400 > Eric Whitney <enwlinux@xxxxxxxxx> wrote: > >> * Theodore Ts'o <tytso@xxxxxxx>: >> > On Tue, Jul 01, 2014 at 09:07:27PM +0900, Jaehoon Chung wrote: >> > > Hi, >> > > >> > > i have interesting for this problem..Because i also found the same problem.. >> > > Is it Journal problem? >> > > >> > > I used the Linux version 3.16.0-rc3. >> > > >> > > [ 3.866449] EXT4-fs error (device mmcblk0p13): ext4_mb_generate_buddy:756: group 0, 20490 clusters in bitmap, 20488 in gd; block bitmap corrupt. >> > > [ 3.877937] Aborting journal on device mmcblk0p13-8. >> > > [ 3.885025] Kernel panic - not syncing: EXT4-fs (device mmcblk0p13): panic forced after error >> > >> > This message means that the file system has detected an inconsistency >> > --- specifically, that the number of blocks marked as in use in the >> > allocation bbitmap is different from what is in the block group >> > descriptors. >> > >> > The file system has been marked to force a panic after an error, at >> > which point e2fsck will be able to repair the inconsistency. >> > >> > What's not clear is *how* the why this happened. It can happen simply >> > because of a hardware problem. (In particular, not all mmc flash >> > devices handle power failures gracefully.) Or it could be a cosmic, >> > ray, or it might be a kernel bug. >> > >> > Normally I would chalk this up to a hardware bug, bug it's possible >> > that it is a kernel bug. If people can reliably reproduce the problem >> > where no power failures or other unclean shutdowns were involved >> > (since the last time file system has been checked using e2fsck) then >> > that would be realy interesting. >> >> Hi Ted: >> >> I saw a similar failure during 3.16-rc3 (plus ext4 stable fixes plus msync >> patch) regression on the Pandaboard this morning. A generic/068 hang >> on data_journal required a reboot for recovery (old bug, though rarer lately). >> On reboot, the root filesystem - default 4K, and on an SD card - went ro >> after the same sort of bad block bitmap / journal abort sequence. Rebooting >> forced a fsck that cleared up the problem. The target test filesystem was on >> a USB-attached disk, and it did not exhibit the same problems on recovery. > > Please be careful about conclusions from regular SD cards and USB sticks for > mass-storage. Unlike hardened eMMC (4.41+), these COTS mass-storage devices > are not meant for intensive use and can perfectly easily corrupt data out of > themselves. I've seen it happening many times already. > >> So, it looks like there might be more than just hardware involved here, >> although eMMC/flash might be a common denominator. I'll see if I can come up >> with a reliable reproducer once the regression pass is finished if someone >> doesn't beat me to it. > > I agree that there is a strong correlation towards flash-based storage, but I > cannot explain why this factor would make a difference. How are flash-based > block-devices different to ext4 than spinning-disk media (besides trim > support)? maybe the zero access time can trigger some race condition? > Best regards, > > -- > David Jander > Protonic Holland. -- Matteo Croce OpenWrt Developer -- 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
