Re: [btrfs] 3626a285f8: divide_error:#[##]

[Qu Wenruo]

On 2022/3/2 16:44, Oliver Sang wrote:
> Hi Qu,
>
> On Tue, Mar 01, 2022 at 03:47:38PM +0800, Qu Wenruo wrote:
> > 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 dedicated 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 @ 3.40GHz 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@xxxxxxxxx>
> > >
> > >
> > > [   65.408303][ T3224] BTRFS info (device sdb2): flagging fs with big metadata feature
> > > [   65.415944][ T3224] BTRFS info (device sdb2): disk space caching is enabled
> > > [   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/sdb3 (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-rc5-00101-g3626a285f87d #1
> > > [   67.837169][ T3293] Hardware name: Dell Inc. OptiPlex 9020/0DNKMN, BIOS A05 12/05/2013
> > > [ 67.844982][ T3293] RIP: 0010:scrub_stripe (kbuild/src/consumer/fs/btrfs/scrub.c:3448 kbuild/src/consumer/fs/btrfs/scrub.c:3486 kbuild/src/consumer/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 there?
> >
> > 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
>
> we tested head of this branch:
>    d6e3a8c42f2fad btrfs: scrub: rename scrub_bio::pagev and related members
> and:
>    fdad4a9615f180 btrfs: introduce dedicated helper to scrub simple-stripe based range
> on this branch.
>
> by attached config.
>
> still reproduce the same issue.
>
> attached dmesgs FYI.

Still failed to reproduce here.

Those btrfs/07[0123] tests are already in scrub/replace group, thus I
ran them almost hourly during the development.


Although there are some ASSERT()s doing extra sanity checks, they should
not affect the result anyway.

Thus I pushed a branch with more explicit BUG_ON()s to catch the
possible divide by zero bugs.
(https://github.com/adam900710/linux/tree/refactor_scrub_testing)

Mind to give it a try?

Thanks,
Qu

> > Thanks,
> > Qu
> >
> > > ========
> > >      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
> > > ===========================================
> > >      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(0000) 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/common.c:39)
> > > [ 67.963395][ T3293] ? kasan_set_track (kbuild/src/consumer/mm/kasan/common.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/include/asm/atomic64_64.h:190 kbuild/src/consumer/include/linux/atomic/atomic-long.h:449 kbuild/src/consumer/include/linux/atomic/atomic-instrumented.h:1790 kbuild/src/consumer/kernel/locking/mutex.c:178 kbuild/src/consumer/kernel/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 file 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 Center
> > > https://lists.01.org/hyperkitty/list/lkp@xxxxxxxxxxxx       Intel Corporation
> > >
> > > Thanks,
> > > Oliver Sang