linux-kernel - Re: [linux-next][bock] [bisected c20cfc27a] WARNING: CPU: 22 PID: 0 at block/blk-core.c:2655 .blk_update

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Message-Id: <1494409780.11532.14.camel@abdul.in.ibm.com>
Date:   Wed, 10 May 2017 15:19:40 +0530
From:   Abdul Haleem <abdhalee@...ux.vnet.ibm.com>
To:     Christoph Hellwig <hch@....de>
Cc:     Jens Axboe <axboe@...nel.dk>, sachinp <sachinp@...ux.vnet.ibm.com>,
        "Martin K. Petersen" <martin.petersen@...cle.com>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-block <linux-block@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...ts.ozlabs.org>
Subject: Re: [linux-next][bock] [bisected c20cfc27a] WARNING: CPU: 22 PID: 0
 at block/blk-core.c:2655 .blk_update_request+0x4f8/0x500

On Wed, 2017-05-10 at 09:56 +0200, Christoph Hellwig wrote:
> On Tue, May 09, 2017 at 08:48:21PM +0530, Abdul Haleem wrote:
> > A bisection for the above suspects resulted a bad commit;
> > 
> > c20cfc27a47307e811346f85959cf3cc07ae42f9 is the first bad commit
> > commit c20cfc27a47307e811346f85959cf3cc07ae42f9
> > Author: Christoph Hellwig <hch@....de>
> > Date:   Wed Apr 5 19:21:07 2017 +0200
> > 
> >     block: stop using blkdev_issue_write_same for zeroing
> 
> And this effectively switches us to use the write_zeroes for SCSI.
> 
> 
> 
> >     
> >     We'll always use the WRITE ZEROES code for zeroing now.
> >     
> >     Signed-off-by: Christoph Hellwig <hch@....de>
> >     Reviewed-by: Martin K. Petersen <martin.petersen@...cle.com>
> >     Reviewed-by: Hannes Reinecke <hare@...e.com>
> >     Signed-off-by: Jens Axboe <axboe@...com>
> > 
> > 
> > @Christoph FYI, the machine configured with 64K page size
> > > 
> > > WARNING: CPU: 12 PID: 0 at block/blk-core.c:2651 .blk_update_request+0x4cc/0x4e0
> 
> Can you decode which warning this is?  Is it:
> 
> 	WARN_ON_ONCE(req->rq_flags & RQF_SPECIAL_PAYLOAD);

Yes it is the one, the Warning shows up only once and if we look at the
below stack trace there is only one WARN_ON_ONCE being called from
blk_update_request function.

WARNING: CPU: 12 PID: 0 at block/blk-core.c:2651 .blk_update_request
+0x4cc/0x4e0
Modules linked in: sg(E) nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E)
grace(E) sunrpc(E) binfmt_misc(E) ip_tables(E) ext4(E) mbcache(E)
jbd2(E) sd_mod(E) ibmvscsi(E) scsi_transport_srp(E) ibmveth(E)
CPU: 12 PID: 0 Comm: swapper/12 Tainted: G            E
4.11.0-autotest #1
task: c0000009f455ee80 task.stack: c0000009fb2e8000
NIP: c00000000050bd1c LR: c00000000050b8ec CTR: c0000000005114b0
REGS: c0000013fff73740 TRAP: 0700   Tainted: G            E
(4.11.0-autotest)
MSR: 8000000000029032 <SF,EE,ME,IR,DR,RI>
  CR: 48042048  XER: 00000001
CFAR: c00000000050bb34 SOFTE: 1 
GPR00: c00000000050b8ec c0000013fff739c0 c000000001389c00
c0000009eca9c800
GPR04: 0000000000000000 0000000000000000 0000000000000001
0000000000000060 
GPR08: 0000000000067887 0000000000000000 c0000009eca9c800
d00000000e5f7e30 
GPR12: 0000000088044044 c00000000e9f6c00 c0000009fb2ebf90
0000000000200042 
GPR16: 00000000ffff9367 c0000013fff70000 0000000000000000
c000000000df4100 
GPR20: c0000000013c3b00 c000000000df4100 0000000000000000
0000000000000005 
GPR24: 0000000000002ee0 c0000000017789f8 0000000000000000
0000000000000000 
GPR28: 0000000000000000 c0000000038ba400 0000000000000000
c0000009eca9c800 
NIP [c00000000050bd1c] .blk_update_request+0x4cc/0x4e0
LR [c00000000050b8ec] .blk_update_request+0x9c/0x4e0
Call Trace:
[c0000013fff739c0] [c00000000050b8ec] .blk_update_request+0x9c/0x4e0
(unreliable)
[c0000013fff73a60] [c0000000006b06fc] .scsi_end_request+0x4c/0x240
[c0000013fff73b10] [c0000000006b4564] .scsi_io_completion+0x1d4/0x6c0
[c0000013fff73be0] [c0000000006a8cd0] .scsi_finish_command+0x100/0x1b0
[c0000013fff73c70] [c0000000006b3978] .scsi_softirq_done+0x188/0x1e0
[c0000013fff73d00] [c000000000516b44] .blk_done_softirq+0xc4/0xf0
[c0000013fff73d90] [c0000000000daef8] .__do_softirq+0x158/0x3b0
[c0000013fff73e90] [c0000000000db5b8] .irq_exit+0x1a8/0x1c0
[c0000013fff73f10] [c000000000014f84] .__do_irq+0x94/0x1f0
[c0000013fff73f90] [c000000000026cbc] .call_do_irq+0x14/0x24
[c0000009fb2eb7f0] [c00000000001516c] .do_IRQ+0x8c/0x100
[c0000009fb2eb890] [c000000000008bf4] hardware_interrupt_common
+0x114/0x120
--- interrupt: 501 at .plpar_hcall_norets+0x14/0x20
    LR = .check_and_cede_processor+0x24/0x40
[c0000009fb2ebb80] [0000000000000002] 0x2 (unreliable)
[c0000009fb2ebbf0] [c0000000007c360c] .dedicated_cede_loop+0x4c/0x150
[c0000009fb2ebc70] [c0000000007c1040] .cpuidle_enter_state+0xb0/0x3b0
[c0000009fb2ebd20] [c00000000012d1bc] .call_cpuidle+0x3c/0x70
[c0000009fb2ebd90] [c00000000012d550] .do_idle+0x280/0x2e0
[c0000009fb2ebe50] [c00000000012d768] .cpu_startup_entry+0x28/0x40
[c0000009fb2ebed0] [c0000000000428a4] .start_secondary+0x304/0x350
[c0000009fb2ebf90] [c00000000000aa6c] start_secondary_prolog+0x10/0x14
Instruction dump:
3f82ff90 3b9cc190 4bfffd8c 3f82ff90 3b9cc1a8 4bfffd80 61290040 b13f0018
4bfffbd4 3cc2ff8b 38c63160 4bfffd9c <0fe00000> 4bfffe18 60000000
60000000 
---[ end trace 0f80359f8fb9c5f4 ]---

> 
> ?  In which case your setup did a partial completion of a WRITE SAME
> command, which is perfectly legal according to SCSI, but a bit unusual.
> 


-- 
Regard's

Abdul Haleem
IBM Linux Technology Centre