On Wed, Jan 23, 2013 at 10:05:04AM -0600, Mitch Harder wrote: > On Wed, Jan 23, 2013 at 1:51 AM, Liu Bo <bo.li.liu@xxxxxxxxxx> wrote: > > On Tue, Jan 22, 2013 at 11:41:19AM -0600, Mitch Harder wrote: > >> On Thu, Jan 17, 2013 at 8:42 AM, Mitch Harder > >> <mitch.harder@xxxxxxxxxxxxxxxx> wrote: > >> > On Wed, Jan 16, 2013 at 6:36 AM, Liu Bo <bo.li.liu@xxxxxxxxxx> wrote: > >> >> This comes from one of btrfs's project ideas, > >> >> As we defragment files, we break any sharing from other snapshots. > >> >> The balancing code will preserve the sharing, and defrag needs to grow this > >> >> as well. > > [...] > >> > > >> > I've been testing this patch on a 3.7.2 kernel merged with the > >> > for-linus branch for the 3.8_rc kernels, and I'm seeing the following > >> > error: > >> > > >> > >> I've reproduced the error with CONFIG_DEBUG_LIST enabled, which shows > >> some problem with an entry in the list. > >> > >> [59312.260441] ------------[ cut here ]------------ > >> [59312.260454] WARNING: at lib/list_debug.c:62 __list_del_entry+0x8d/0x98() > >> [59312.260458] Hardware name: OptiPlex 745 > >> [59312.260461] list_del corruption. next->prev should be > >> ffff88006511c438, but was dead000000200200 > > > > LIST_POISON2 -> (000000200200) > > So we can know that the next one is deleted from the list even _earlier_ > > than the current one is. > > > > Any other messages before this warning complains? > > > > Just some normal feedback from a metadata balance I had run. Well, these do fit my expectation, since balance also involves with playing with root_list, which may lead to the bad situation. > > [14057.193343] device fsid 28c688c5-7dbd-4071-b271-1bf6726d8835 devid > 1 transid 4 /dev/sda7 > [14057.194438] btrfs: force lzo compression > [14057.194446] btrfs: enabling auto defrag > [14057.194449] btrfs: disk space caching is enabled > [14057.194452] btrfs flagging fs with big metadata feature > [14057.194455] btrfs: lzo incompat flag set. > [57508.799193] btrfs: relocating block group 14516486144 flags 4 > [57632.178797] btrfs: found 6775 extents > [57633.214701] btrfs: relocating block group 11832131584 flags 4 > [57776.400102] btrfs: found 6480 extents > [57777.021175] btrfs: relocating block group 10489954304 flags 4 > [57949.182725] btrfs: found 6681 extents > [59312.260441] ------------[ cut here ]------------ > [59312.260454] WARNING: at lib/list_debug.c:62 __list_del_entry+0x8d/0x98() > [59312.260458] Hardware name: OptiPlex 745 > ... > > I'm going to try to wrap some debugging around the section of code in > btrfs_clean_old_snapshots() where the dead_roots list is spliced onto > the root list being processed. The double entry may be slipping in > here. > > 1764 spin_lock(&fs_info->trans_lock); > 1765 list_splice_init(&fs_info->dead_roots, &list); > 1766 spin_unlock(&fs_info->trans_lock); hmm, I don't think there is anything wrong in this code. But you can give it a shot anyway :) thanks, liubo -- To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html