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Date:   Tue, 1 Mar 2022 15:47:38 +0800
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To:     kernel test robot <oliver.sang@intel.com>, Qu Wenruo <wqu@suse.com>
Cc:     David Sterba <dsterba@suse.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Memory Management List <linux-mm@kvack.org>,
        lkp@lists.01.org, lkp@intel.com, linux-btrfs@vger.kernel.org
References: <20220301063026.GB13547@xsang-OptiPlex-9020>
From:   Qu Wenruo <quwenruo.btrfs@gmx.com>
Subject: Re: [btrfs] 3626a285f8: divide_error:#[##]
In-Reply-To: <20220301063026.GB13547@xsang-OptiPlex-9020>
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On 2022/3/1 14:30, kernel test robot wrote:
>
>
> Greeting,
>
> FYI, we noticed the following commit (built with gcc-9):
>
> commit: 3626a285f87dceb4ca649d0ef015d7b295206cdf ("btrfs: introduce dedi=
cated helper to scrub simple-stripe based range")
> https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git master
>
> in testcase: xfstests
> version: xfstests-x86_64-1de1db8-1_20220217
> with following parameters:
>
> 	disk: 6HDD
> 	fs: btrfs
> 	test: btrfs-group-07
> 	ucode: 0x28
>
> test-description: xfstests is a regression test suite for xfs and other =
files ystems.
> test-url: git://git.kernel.org/pub/scm/fs/xfs/xfstests-dev.git
>
>
> on test machine: 8 threads 1 sockets Intel(R) Core(TM) i7-4770 CPU @ 3.4=
0GHz with 8G memory
>
> caused below changes (please refer to attached dmesg/kmsg for entire log=
/backtrace):
>
>
>
> If you fix the issue, kindly add following tag
> Reported-by: kernel test robot <oliver.sang@intel.com>
>
>
> [   65.408303][ T3224] BTRFS info (device sdb2): flagging fs with big me=
tadata feature
> [   65.415944][ T3224] BTRFS info (device sdb2): disk space caching is e=
nabled
> [   65.422842][ T3224] BTRFS info (device sdb2): has skinny extents
> [   65.436656][ T3224] BTRFS info (device sdb2): checking UUID tree
> [   66.134430][ T3293] BTRFS info (device sdb2): dev_replace from /dev/s=
db3 (devid 2) to /dev/sdb6 started
> [   67.823326][ T3293] divide error: 0000 [#1] SMP KASAN PTI
> [   67.828668][ T3293] CPU: 3 PID: 3293 Comm: btrfs Not tainted 5.17.0-r=
c5-00101-g3626a285f87d #1
> [   67.837169][ T3293] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BI=
OS A05 12/05/2013
> [ 67.844982][ T3293] RIP: 0010:scrub_stripe (kbuild/src/consumer/fs/btrf=
s/scrub.c:3448 kbuild/src/consumer/fs/btrfs/scrub.c:3486 kbuild/src/consum=
er/fs/btrfs/scrub.c:3644) btrfs
> [ 67.850976][ T3293] Code: 00 00 fc ff df 48 89 f9 48 c1 e9 03 0f b6 0c =
11 48 89 fa 83 e2 07 83 c2 03 38 ca 7c 08 84 c9 0f 85 27 09 00 00 41 8b 5d=
 1c 99 <f7> fb 48 8b 54 24 30 48 c1 ea 03 48 63 e8 48 b8 00 00 00 00 00 fc
> All code

This is weird, the code is from simple_stripe_full_stripe_len(), which
means the chunk map must be RAID0 or RAID10.

In that case, their sub_stripes should be either 1 or 2, why we got 0 ther=
e?

In fact, from volumes.c, all sub_stripes is from btrfs_raid_array[],
which all have either 1 or 2 sub_stripes.


Although the code is old, not the latest version, it should still not
cause such problem.

Mind to retest with my branch to see if it can be reproduced?
https://github.com/adam900710/linux/tree/refactor_scrub

Thanks,
Qu

> =3D=3D=3D=3D=3D=3D=3D=3D
>     0:	00 00                	add    %al,(%rax)
>     2:	fc                   	cld
>     3:	ff                   	(bad)
>     4:	df 48 89             	fisttps -0x77(%rax)
>     7:	f9                   	stc
>     8:	48 c1 e9 03          	shr    $0x3,%rcx
>     c:	0f b6 0c 11          	movzbl (%rcx,%rdx,1),%ecx
>    10:	48 89 fa             	mov    %rdi,%rdx
>    13:	83 e2 07             	and    $0x7,%edx
>    16:	83 c2 03             	add    $0x3,%edx
>    19:	38 ca                	cmp    %cl,%dl
>    1b:	7c 08                	jl     0x25
>    1d:	84 c9                	test   %cl,%cl
>    1f:	0f 85 27 09 00 00    	jne    0x94c
>    25:	41 8b 5d 1c          	mov    0x1c(%r13),%ebx
>    29:	99                   	cltd
>    2a:*	f7 fb                	idiv   %ebx		<-- trapping instruction
>    2c:	48 8b 54 24 30       	mov    0x30(%rsp),%rdx
>    31:	48 c1 ea 03          	shr    $0x3,%rdx
>    35:	48 63 e8             	movslq %eax,%rbp
>    38:	48                   	rex.W
>    39:	b8 00 00 00 00       	mov    $0x0,%eax
>    3e:	00 fc                	add    %bh,%ah
>
> Code starting with the faulting instruction
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
>     0:	f7 fb                	idiv   %ebx
>     2:	48 8b 54 24 30       	mov    0x30(%rsp),%rdx
>     7:	48 c1 ea 03          	shr    $0x3,%rdx
>     b:	48 63 e8             	movslq %eax,%rbp
>     e:	48                   	rex.W
>     f:	b8 00 00 00 00       	mov    $0x0,%eax
>    14:	00 fc                	add    %bh,%ah
> [   67.870187][ T3293] RSP: 0018:ffffc9000a71f450 EFLAGS: 00010246
> [   67.876028][ T3293] RAX: 0000000000000004 RBX: 0000000000000000 RCX: =
0000000000000000
> [   67.883756][ T3293] RDX: 0000000000000000 RSI: 0000000000000004 RDI: =
ffff888129ec6d1c
> [   67.891491][ T3293] RBP: ffff8881453682a0 R08: 0000000000000001 R09: =
0000000000000000
> [   67.899230][ T3293] R10: ffff88821534a063 R11: ffffed1042a6940c R12: =
ffff888121238000
> [   67.906955][ T3293] R13: ffff888129ec6d00 R14: ffff888145368000 R15: =
0000000000000008
> [   67.914680][ T3293] FS:  00007f2851eb08c0(0000) GS:ffff8881a6d80000(0=
000) knlGS:0000000000000000
> [   67.923351][ T3293] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [   67.929709][ T3293] CR2: 00007ffea4ff07f8 CR3: 000000010a0fc005 CR4: =
00000000001706e0
> [   67.937437][ T3293] DR0: 0000000000000000 DR1: 0000000000000000 DR2: =
0000000000000000
> [   67.945163][ T3293] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: =
0000000000000400
> [   67.952891][ T3293] Call Trace:
> [   67.955992][ T3293]  <TASK>
> [ 67.958749][ T3293] ? kasan_save_stack (kbuild/src/consumer/mm/kasan/co=
mmon.c:39)
> [ 67.963395][ T3293] ? kasan_set_track (kbuild/src/consumer/mm/kasan/com=
mon.c:45)
> [ 67.967951][ T3293] ? kasan_set_free_info (kbuild/src/consumer/mm/kasan=
/generic.c:372)
> [ 67.972851][ T3293] ? mutex_unlock (kbuild/src/consumer/arch/x86/includ=
e/asm/atomic64_64.h:190 kbuild/src/consumer/include/linux/atomic/atomic-lo=
ng.h:449 kbuild/src/consumer/include/linux/atomic/atomic-instrumented.h:17=
90 kbuild/src/consumer/kernel/locking/mutex.c:178 kbuild/src/consumer/kern=
el/locking/mutex.c:537)
>
>
> To reproduce:
>
>          git clone https://github.com/intel/lkp-tests.git
>          cd lkp-tests
>          sudo bin/lkp install job.yaml           # job file is attached =
in this email
>          bin/lkp split-job --compatible job.yaml # generate the yaml fil=
e for lkp run
>          sudo bin/lkp run generated-yaml-file
>
>          # if come across any failure that blocks the test,
>          # please remove ~/.lkp and /lkp dir to run from a clean state.
>
>
>
> ---
> 0DAY/LKP+ Test Infrastructure                   Open Source Technology C=
enter
> https://lists.01.org/hyperkitty/list/lkp@lists.01.org       Intel Corpor=
ation
>
> Thanks,
> Oliver Sang
>