On Thu, Mar 29, 2012 at 12:52:35PM +0200, Sander wrote:
> Hello all,
>
> I can't seem to balance my btrfs filesystem. It segfaults, and gives a
> kernel bug:
>
> [ 1355.139099] ------------[ cut here ]------------
> [ 1355.139099] kernel BUG at fs/btrfs/volumes.c:2733!
> [ 1355.149322] Internal error: Oops - BUG: 0 [#1] SMP
> [ 1355.149322] Modules linked in:
> [ 1355.154479] CPU: 0 Not tainted (3.3.0 #8)
> [ 1355.162109] PC is at btrfs_balance+0x312/0xb04
> [ 1355.166778] LR is at btrfs_run_delayed_iputs+0x2d/0xac
> [ 1355.166931] pc : [<c0138c3a>] lr : [<c01234d5>] psr: 60000033
> [ 1355.166931] sp : cb141d98 ip : 00000000 fp : be83fdb4
> [ 1355.166931] r10: 00000000 r9 : 00000000 r8 : 00000000
> [ 1355.184173] r7 : 00000000 r6 : ffffffef r5 : ede7f000 r4 : ed730e00
> [ 1355.189636] r3 : 00000000 r2 : 00000000 r1 : 00000000 r0 : 00000007
> [ 1355.203277] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment
> user
> [ 1355.203277] Control: 50c5387d Table: 8b15c04a DAC: 00000015
> [ 1355.203277] Process btrfs (pid: 1798, stack limit = 0xcb1402f8)
> [ 1355.203277] Stack: (0xcb141d98 to 0xcb142000)
> [ 1355.203277] 1d80:
> c145f944 ffffffff
> [ 1355.227691] 1da0: 00000000 00000000 00000000 00000000 00000003 ee478d40
> 00000015 00000000
> [ 1355.227691] 1dc0: 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000 00000000
> [ 1355.253356] 1de0: 00000000 00000000 00000000 00000000 00000000 00000000
> ede7fcd4 ede7fcd8
> [ 1355.253356] 1e00: 00000000 00000000 00000000 00000000 00000000 271aee1c
> 000200da c0160fd5
> [ 1355.253356] 1e20: ed74ec00 00000000 d6257680 00000000 ed730e00 00000000
> ede7f4e8 ede7fcb0
> [ 1355.279022] 1e40: ede7f000 00000000 be83fdb4 c013d489 eec9c118 be83ebf8
> ed74ec00 eec8a370
> [ 1355.279022] 1e60: d6257680 00000000 eec8a528 00000000 be83fdb4 c013fc6b
> 0000001d 000000eb
> [ 1355.279022] 1e80: 00000007 00000001 e6f7e680 c015cecd cb141ea4 00000000
> cb141ef0 00000000
> [ 1355.296142] 1ea0: cb15c000 01ffffff 00000000 ffffffff 00000001 00000000
> eeabaac0 00000001
> [ 1355.296142] 1ec0: ed5428c0 c1414788 d6257688 000000eb cb141ef0 c016011b
> cb141ef0 00000000
> [ 1355.321807] 1ee0: 00000001 c016018f 00000000 00000817 00000001 271aee1c
> ede92250 d6257680
> [ 1355.321807] 1f00: be83ebf8 be83ebf8 eec8a528 00000000 cb140000 00000000
> be83fdb4 c0088075
> [ 1355.321807] 1f20: 00004000 c00887ff 00000000 00000000 00000000 00000000
> 00000000 00000000
> [ 1355.338928] 1f40: 00000000 00000000 00000000 00000000 00000000 271aee1c
> 00000003 d6257680
> [ 1355.338928] 1f60: be83ebf8 5000940c d6257680 be83ebf8 5000940c 00000003
> 00000000 cb140000
> [ 1355.364593] 1f80: 00000000 c008885d 00000003 00000000 be83fec7 00000003
> 0013c478 00000036
> [ 1355.364593] 1fa0: c000c5a4 c000c401 be83fec7 00000003 00000003 5000940c
> be83ebf8 be83fbf8
> [ 1355.364593] 1fc0: be83fec7 00000003 0013c478 00000036 00000002 0000b7ad
> 00000001 be83fdb4
> [ 1355.381713] 1fe0: 00024b3d be83ebf0 0000b7f7 b6ea7f9c 80000010 00000003
> 00052d17 00090224
> [ 1355.381713] [<c0138c3a>] (btrfs_balance+0x312/0xb04) from [<c013d489>]
> (btrfs_ioctl_balance+0x109/0x174)
> [ 1355.381713] [<c013d489>] (btrfs_ioctl_balance+0x109/0x174) from
> [<c013fc6b>] (btrfs_ioctl+0xbf5/0xd42)
> [ 1355.418518] [<c013fc6b>] (btrfs_ioctl+0xbf5/0xd42) from [<c0088075>]
> (vfs_ioctl+0xd/0x28)
> [ 1355.418518] [<c0088075>] (vfs_ioctl+0xd/0x28) from [<c00887ff>]
> (do_vfs_ioctl+0x35d/0x38e)
> [ 1355.427093] [<c00887ff>] (do_vfs_ioctl+0x35d/0x38e) from [<c008885d>]
> (sys_ioctl+0x2d/0x44)
> [ 1355.444488] [<c008885d>] (sys_ioctl+0x2d/0x44) from [<c000c401>]
> (ret_fast_syscall+0x1/0x44)
> [ 1355.444488] Code: d107 f116 0f11 d100 (de02) 4620
> [ 1355.458343] ---[ end trace f06b6b8fcd08e6d5 ]---
>
> A new 'btrfs filesystem balance /' seems to just hang, and is
> unkillable.
>
> After a reboot, I tried again, with the same result:
>
> [ 81.048767] ------------[ cut here ]------------
> [ 81.053619] kernel BUG at fs/btrfs/volumes.c:2733!
> [ 81.053619] Internal error: Oops - BUG: 0 [#1] SMP
> [ 81.059295] Modules linked in:
> [ 81.059295] CPU: 1 Not tainted (3.3.0 #8)
> [ 81.071411] PC is at btrfs_balance+0x312/0xb04
> [ 81.074890] LR is at btrfs_run_delayed_iputs+0x2d/0xac
> [ 81.074890] pc : [<c0138c3a>] lr : [<c01234d5>] psr: 60000133
> [ 81.074890] sp : edda5d98 ip : 00000000 fp : beb62d64
> [ 81.093475] r10: 00000000 r9 : 00000000 r8 : 00000000
> [ 81.098327] r7 : 00000000 r6 : ffffffef r5 : ed73f000 r4 : ee311c00
> [ 81.098327] r3 : 00000000 r2 : 00000000 r1 : 00000000 r0 : 00000007
> [ 81.112609] Flags: nZCv IRQs on FIQs on Mode SVC_32 ISA Thumb Segment
> user
> [ 81.112609] Control: 50c5387d Table: a7fb404a DAC: 00000015
> [ 81.112609] Process btrfs (pid: 752, stack limit = 0xedda42f8)
> [ 81.132354] Stack: (0xedda5d98 to 0xedda6000)
> [ 81.132354] 5d80:
> c145f944 ffffffff
> [ 81.145477] 5da0: 00000000 00000000 00000000 00000000 00000003 eeabca40
> 00000015 00000000
> [ 81.145477] 5dc0: 00000000 00000000 00000000 00000000 00000000 00000000
> 00000000 00000000
> [ 81.145477] 5de0: 00000000 00000000 00000000 00000000 00000000 00000000
> ed73fcd4 ed73fcd8
> [ 81.162597] 5e00: 00000000 00000000 00000000 00000000 00000000 271aee1c
> 000200da c0160fd5
> [ 81.162597] 5e20: ed784c00 00000000 ee117cc0 00000000 ee311c00 00000000
> ed73f4e8 ed73fcb0
> [ 81.188262] 5e40: ed73f000 00000000 beb62d64 c013d489 eec7ace8 beb61ba8
> ed784c00 eecd5370
> [ 81.188262] 5e60: ee117cc0 00000000 eecd5528 00000000 beb62d64 c013fc6b
> 0000001d 000000ec
> [ 81.199951] 5e80: 00000007 00000001 ed74f200 c015cecd edda5ea4 00000000
> edda5ef0 00000000
> [ 81.199951] 5ea0: e7fb4050 01ffffff 00000000 ffffffff 00000001 00000000
> eea3c740 00000001
> [ 81.199951] 5ec0: eebe59c0 c1414788 ee117cc8 000000ec edda5ef0 c016011b
> edda5ef0 00000000
> [ 81.222503] 5ee0: 00000001 c016018f 00000000 00000817 00000001 271aee1c
> ede92250 ee117cc0
> [ 81.222503] 5f00: beb61ba8 beb61ba8 eecd5528 00000000 edda4000 00000000
> beb62d64 c0088075
> [ 81.248168] 5f20: 00004000 c00887ff 00000000 00000000 00000000 00000000
> 00000000 00000000
> [ 81.248168] 5f40: 00000000 00000000 00000000 00000000 00000000 271aee1c
> 00000003 ee117cc0
> [ 81.248168] 5f60: beb61ba8 5000940c ee117cc0 beb61ba8 5000940c 00000003
> 00000000 edda4000
> [ 81.273834] 5f80: 00000000 c008885d 00000003 00000000 beb62e8c 00000003
> 01438478 00000036
> [ 81.273834] 5fa0: c000c5a4 c000c401 beb62e8c 00000003 00000003 5000940c
> beb61ba8 beb62ba8
> [ 81.290954] 5fc0: beb62e8c 00000003 01438478 00000036 00000002 0000b7ad
> 00000001 beb62d64
> [ 81.293914] 5fe0: 00024b3d beb61ba0 0000b7f7 b6ee7f9c 80000110 00000003
> 372a242a 72d76d15
> [ 81.293914] [<c0138c3a>] (btrfs_balance+0x312/0xb04) from [<c013d489>]
> (btrfs_ioctl_balance+0x109/0x174)
> [ 81.309387] [<c013d489>] (btrfs_ioctl_balance+0x109/0x174) from
> [<c013fc6b>] (btrfs_ioctl+0xbf5/0xd42)
> [ 81.309387] [<c013fc6b>] (btrfs_ioctl+0xbf5/0xd42) from [<c0088075>]
> (vfs_ioctl+0xd/0x28)
> [ 81.309387] [<c0088075>] (vfs_ioctl+0xd/0x28) from [<c00887ff>]
> (do_vfs_ioctl+0x35d/0x38e)
> [ 81.345001] [<c00887ff>] (do_vfs_ioctl+0x35d/0x38e) from [<c008885d>]
> (sys_ioctl+0x2d/0x44)
> [ 81.345001] [<c008885d>] (sys_ioctl+0x2d/0x44) from [<c000c401>]
> (ret_fast_syscall+0x1/0x44)
> [ 81.345001] Code: d107 f116 0f11 d100 (de02) 4620
> [ 81.367645] ---[ end trace 6b16e1c6e6a2dd9c ]---
So you have balance item on disk, but the kernel doesn't seem to know
about it in advance, which is odd and so when you try to run balance it
panics on one of the safety checks.
>
>
> The system is a pandaboard running a plain Linus kernel 3.3.0 with a
> btrfs filesystem, over two Intel 320 600GB ssd's, connected via usb (on
> an usb hub), on top of md_crypt. Mount options:
> "subvol=rootvolume,space_cache,inode_cache,compress=lzo,ssd"
>
> Before the balance, I deleted about 2500 snapshots and waited for the
> btrfs kernel threads to calm down. Then I initiated a btrfs filesystem
> scrub. Unfortunately during the scrub, the filesystem balance started.
> Might be related.
That's indeed pretty cool, I wonder how that could happen. I'm
definitely intrested in reproducing it. Could you please umount this
filesystem, capture the output of 'btrfs-debug-tree -d <dev>' and post
it somewhere ? After that mount it back and see if there is "btrfs:
continuing balance" line in dmesg (and if btrfs-balance kthread shows
up) ? If so, just let it run, it should finish the balance and remove
on-disk item. (You can query the status of running balance with 'btrfs
balance status <mnt>')
Thanks,
Ilya
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