zfs on 32bit: xattr causes oops

[adeeln]

While getting ZFS to work on a 32bit box, I encountered a bug where accessing any file caused an oops...here's the log:

2012-03-04T21:34:58.062225-05:00 localhost kernel: BUG: unable to handle kernel NULL pointer dereference at 000000e6
Message from syslogd@localhost at Mar 4 21:34:58 ...kernel:Oops: 0000 [#1] SMP
Message from syslogd@localhost at Mar 4 21:34:58 ... kernel:Process ls (pid: 3751, ti=5c478000 task=5bfc2300 task.ti=5c478000)
Message from syslogd@localhost at Mar 4 21:34:58 ... kernel:Stack:
Message from syslogd@localhost at Mar 4 21:34:58 ... kernel:Call Trace:
Message from syslogd@localhost at Mar 4 21:34:58 ... kernel:Code: 58 20 8b 5b 18 8b 5b 4c 85 db 74 04 ff d3 89 c6 89 f0 5b 5e 5d c3 55 89 e5 57 89 c7 56 31 c0 53 83 ec 08 8b 32 85 f6 75 2e eb 35 <8b> 08 89 45 ec 89 4d f0 89 f1 eb 04 ff 45 f0 41 8b 45 f0 8a 18
Message from syslogd@localhost at Mar 4 21:34:58 ... kernel:EIP: [<401a5e4d>] xattr_resolve_name+0x15/0x51 SS:ESP 0068:5c479e20
Message from syslogd@localhost at Mar 4 21:34:58 ... kernel:CR2: 00000000000000e6
2012-03-04T21:34:58.062288-05:00 localhost kernel: IP: [<401a5e4d>] xattr_resolve_name+0x15/0x51
2012-03-04T21:34:58.062294-05:00 localhost kernel: *pde = 00000000
2012-03-04T21:34:58.062298-05:00 localhost kernel: Oops: 0000 [#1] SMP
2012-03-04T21:34:58.062307-05:00 localhost kernel: Modules linked in: ipv6 zfs(P) zcommon(P) znvpair(P) zavl(P) zunicode(P) spl(O) i2c_i801 processor evdev thermal_sys i2c_core container button scsi_transport_iscsi e1000 zlib_deflate ext4 jbd2 mbcache scsi_wait_scan usbhid ohci_hcd uhci_hcd usb_storage ehci_hcd usbcore usb_common ata_piix ahci libahci
2012-03-04T21:34:58.062312-05:00 localhost kernel:
2012-03-04T21:34:58.062319-05:00 localhost kernel: Pid: 3751, comm: ls Tainted: P O 3.2.1-gentoo-r2 #2 Supermicro X5DP8/X5DP8
2012-03-04T21:34:58.062325-05:00 localhost kernel: EIP: 0060:[<401a5e4d>] EFLAGS: 00010202 CPU: 0
2012-03-04T21:34:58.062332-05:00 localhost kernel: EIP is at xattr_resolve_name+0x15/0x51
2012-03-04T21:34:58.062337-05:00 localhost kernel: EAX: 000000e6 EBX: 401a5e75 ECX: 5c479e84 EDX: 5c479e48
2012-03-04T21:34:58.062342-05:00 localhost kernel: ESI: 5c479e84 EDI: 5ff6d9e0 EBP: 5c479e34 ESP: 5c479e20
2012-03-04T21:34:58.062347-05:00 localhost kernel: DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
2012-03-04T21:34:58.062351-05:00 localhost kernel: Process ls (pid: 3751, ti=5c478000 task=5bfc2300 task.ti=5c478000)
2012-03-04T21:34:58.062355-05:00 localhost kernel: Stack:
2012-03-04T21:34:58.062360-05:00 localhost kernel: 5ff57438 5ff696ed 401a5e89 5c33b780 5c33b780 5c479e54 401a5ea7 401a6102
2012-03-04T21:34:58.062365-05:00 localhost kernel: 00000004 00000000 5c479e84 401a5e89 5c479e84 5c479e70 401a61ee 00000000
2012-03-04T21:34:58.062370-05:00 localhost kernel: 00000000 00000017 00000000 00000000 5c479f90 401a6280 00000000 00000000
2012-03-04T21:34:58.062374-05:00 localhost kernel: Call Trace:
2012-03-04T21:34:58.062379-05:00 localhost kernel: [<401a5e89>] ? xattr_resolve_name+0x51/0x51
2012-03-04T21:34:58.062383-05:00 localhost kernel: [<401a5ea7>] generic_getxattr+0x1e/0x48
2012-03-04T21:34:58.062388-05:00 localhost kernel: [<401a6102>] ? xattr_permission+0x53/0xed
2012-03-04T21:34:58.062393-05:00 localhost kernel: [<401a5e89>] ? xattr_resolve_name+0x51/0x51
2012-03-04T21:34:58.062494-05:00 localhost kernel: [<401a61ee>] vfs_getxattr+0x52/0x59
2012-03-04T21:34:58.062504-05:00 localhost kernel: [<401a6280>] getxattr+0x8b/0xde
2012-03-04T21:34:58.062512-05:00 localhost kernel: [<40199305>] ? path_lookupat+0x4ad/0x501
2012-03-04T21:34:58.062518-05:00 localhost kernel: [<4019a062>] ? user_path_at_empty+0x4c/0x68
2012-03-04T21:34:58.062522-05:00 localhost kernel: [<4019a062>] ? user_path_at_empty+0x4c/0x68
2012-03-04T21:34:58.062527-05:00 localhost kernel: [<4019a098>] ? user_path_at+0x1a/0x1f
2012-03-04T21:34:58.062531-05:00 localhost kernel: [<401a6846>] sys_getxattr+0x3a/0x4c
2012-03-04T21:34:58.062536-05:00 localhost kernel: [<40360290>] sysenter_do_call+0x12/0x26
2012-03-04T21:34:58.062544-05:00 localhost kernel: Code: 58 20 8b 5b 18 8b 5b 4c 85 db 74 04 ff d3 89 c6 89 f0 5b 5e 5d c3 55 89 e5 57 89 c7 56 31 c0 53 83 ec 08 8b 32 85 f6 75 2e eb 35 <8b> 08 89 45 ec 89 4d f0 89 f1 eb 04 ff 45 f0 41 8b 45 f0 8a 18
2012-03-04T21:34:58.062550-05:00 localhost kernel: EIP: [<401a5e4d>] xattr_resolve_name+0x15/0x51 SS:ESP 0068:5c479e20
2012-03-04T21:34:58.062554-05:00 localhost kernel: CR2: 00000000000000e6
2012-03-04T21:34:58.062559-05:00 localhost kernel: ---[ end trace 78a8dec2e46fec25 ]---

The temporary fix was to set the xattr attribute in zfs off, i.e. zfs set xattr=off tank/ROOT

[behlendorf]

Thanks for filing this and mentioning it was a 32-bit issue. If you could also include the distribution and kernel version in the bug report that would be helpful.

[adeeln]

Sure, sorry; its a Gentoo install, using sys-kernel/gentoo-sources-3.2.1-r2 & the in portage-tree genkernel-9999

[behlendorf]

Can you please give the above patch a try, I expect it will resolve the issue. Unfortunately, I wasn't able to reproduce it locally.

[adeeln]

Yup, the patch seems to have resolved the oops; at least I can't reproduce it anymore with the same setup/commands. For completeness, I was copying from an ext4 mounted root partition to a mounted zfs partition with:

rsync -rax --exclude /proc --exclude /dev --exclude /sys --exclude /tmp --exclude /mnt / /mnt/gentoo

doing a cp -a also caused the problem. The only way I was able to do any copying was by using: tar cp / | tar xfp -C /mnt/gentoo

The ext4 partition was mounted as:
/dev/sda2 on / type ext4 (rw,noatime,user_xattr,barrier=1,data=ordered)

while the zfs partition was mounted as:
system/ROOT on /mnt/gentoo type zfs (rw)