On 2/6/13 3:28 PM, Steve Wise wrote:
On 2/6/2013 4:24 PM, J. Bruce Fields wrote:
On Wed, Feb 06, 2013 at 05:48:15PM +0200, Yan Burman wrote:
When killing mount command that got stuck:
-------------------------------------------
BUG: unable to handle kernel paging request at ffff880324dc7ff8
IP: [<ffffffffa05f3dfb>] rdma_read_xdr+0x8bb/0xd40 [svcrdma]
PGD 1a0c063 PUD 32f82e063 PMD 32f2fd063 PTE 8000000324dc7161
Oops: 0003 [#1] PREEMPT SMP
Modules linked in: md5 ib_ipoib xprtrdma svcrdma rdma_cm ib_cm iw_cm
ib_addr nfsd exportfs netconsole ip6table_filter ip6_tables
iptable_filter ip_tables ebtable_nat nfsv3 nfs_acl ebtables x_tables
nfsv4 auth_rpcgss nfs lockd autofs4 sunrpc target_core_iblock
target_core_file target_core_pscsi target_core_mod configfs 8021q
bridge stp llc ipv6 dm_mirror dm_region_hash dm_log vhost_net
macvtap macvlan tun uinput iTCO_wdt iTCO_vendor_support kvm_intel
kvm crc32c_intel microcode pcspkr joydev i2c_i801 lpc_ich mfd_core
ehci_pci ehci_hcd sg ioatdma ixgbe mdio mlx4_ib ib_sa ib_mad ib_core
mlx4_en mlx4_core igb hwmon dca ptp pps_core button dm_mod ext3 jbd
sd_mod ata_piix libata uhci_hcd megaraid_sas scsi_mod
CPU 6
Pid: 4744, comm: nfsd Not tainted 3.8.0-rc5+ #4 Supermicro
X8DTH-i/6/iF/6F/X8DTH
RIP: 0010:[<ffffffffa05f3dfb>] [<ffffffffa05f3dfb>]
rdma_read_xdr+0x8bb/0xd40 [svcrdma]
RSP: 0018:ffff880324c3dbf8 EFLAGS: 00010297
RAX: ffff880324dc8000 RBX: 0000000000000001 RCX: ffff880324dd8428
RDX: ffff880324dc7ff8 RSI: ffff880324dd8428 RDI: ffffffff81149618
RBP: ffff880324c3dd78 R08: 000060f9c0000860 R09: 0000000000000001
R10: ffff880324dd8000 R11: 0000000000000001 R12: ffff8806299dcb10
R13: 0000000000000003 R14: 0000000000000001 R15: 0000000000000010
FS: 0000000000000000(0000) GS:ffff88063fc00000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: ffff880324dc7ff8 CR3: 0000000001a0b000 CR4: 00000000000007e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
Process nfsd (pid: 4744, threadinfo ffff880324c3c000, task
ffff880330550000)
Stack:
ffff880324c3dc78 ffff880324c3dcd8 0000000000000282 ffff880631cec000
ffff880324dd8000 ffff88062ed33040 0000000124c3dc48 ffff880324dd8000
ffff88062ed33058 ffff880630ce2b90 ffff8806299e8000 0000000000000003
Call Trace:
[<ffffffffa05f466e>] svc_rdma_recvfrom+0x3ee/0xd80 [svcrdma]
[<ffffffff81086540>] ? try_to_wake_up+0x2f0/0x2f0
[<ffffffffa045963f>] svc_recv+0x3ef/0x4b0 [sunrpc]
[<ffffffffa0571db0>] ? nfsd_svc+0x740/0x740 [nfsd]
[<ffffffffa0571e5d>] nfsd+0xad/0x130 [nfsd]
[<ffffffffa0571db0>] ? nfsd_svc+0x740/0x740 [nfsd]
[<ffffffff81071df6>] kthread+0xd6/0xe0
[<ffffffff81071d20>] ? __init_kthread_worker+0x70/0x70
[<ffffffff814b462c>] ret_from_fork+0x7c/0xb0
[<ffffffff81071d20>] ? __init_kthread_worker+0x70/0x70
Code: 63 c2 49 8d 8c c2 18 02 00 00 48 39 ce 77 e1 49 8b 82 40 0a 00
00 48 39 c6 0f 84 92 f7 ff ff 90 48 8d 50 f8 49 89 92 40 0a 00 00
<48> c7 40 f8 00 00 00 00 49 8b 82 40 0a 00 00 49 3b 82 30 0a 00
RIP [<ffffffffa05f3dfb>] rdma_read_xdr+0x8bb/0xd40 [svcrdma]
RSP <ffff880324c3dbf8>
CR2: ffff880324dc7ff8
---[ end trace 06d0384754e9609a ]---
It seems that commit afc59400d6c65bad66d4ad0b2daf879cbff8e23e
"nfsd4: cleanup: replace rq_resused count by rq_next_page pointer"
is responsible for the crash (it seems to be crashing in
net/sunrpc/xprtrdma/svc_rdma_recvfrom.c:527)
It may be because I have CONFIG_DEBUG_SET_MODULE_RONX and
CONFIG_DEBUG_RODATA enabled. I did not try to disable them yet.
When I moved to commit 79f77bf9a4e3dd5ead006b8f17e7c4ff07d8374e I
was no longer getting the server crashes,
so the reset of my tests were done using that point (it is somewhere
in the middle of 3.7.0-rc2).
OK, so this part's clearly my fault--I'll work on a patch, but the
rdma's use of the ->rq_pages array is pretty confusing.
Maybe Tom can shed some light?
Yes, the RDMA transport has two confusing tweaks on rq_pages. Most
transports (UDP/TCP) use the rq_pages allocated by SVC. For RDMA,
however, the RQ already contains pre-allocated memory that will contain
inbound NFS requests from the client. Instead of copying this data from
the per-registered receive buffer into the buffer in rq_pages, I just
replace the page in rq_pages with the one that already contains the data.
The second somewhat strange thing is that the NFS request contains an
NFSRDMA header. This is just like TCP (i.e. the 4B length), however, the
difference is that (unlike TCP) this header is needed for the response
because it maps out where in the client the response data will be written.
Tom
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