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* WARNING in get_unlocked_entry
@ 2018-10-30 15:00 syzbot
  2018-10-31  3:18 ` Matthew Wilcox
  0 siblings, 1 reply; 6+ messages in thread
From: syzbot @ 2018-10-30 15:00 UTC (permalink / raw)
  To: jack, linux-fsdevel, linux-kernel, syzkaller-bugs, viro, willy, zwisler

Hello,

syzbot found the following crash on:

HEAD commit:    4b42745211af Merge tag 'armsoc-soc' of git://git.kernel.or..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1187d06d400000
kernel config:  https://syzkaller.appspot.com/x/.config?x=93932074d01b4a5
dashboard link: https://syzkaller.appspot.com/bug?extid=4fd0c066d82852499145
compiler:       gcc (GCC) 8.0.1 20180413 (experimental)

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+4fd0c066d82852499145@syzkaller.appspotmail.com

EXT4-fs (sda1): Cannot specify journal on remount
EXT4-fs (sda1): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
EXT4-fs (sda1): warning: refusing change of dax flag with busy inodes while  
remounting
WARNING: CPU: 0 PID: 12870 at fs/dax.c:227 get_unlocked_entry+0x3ac/0x4d0  
fs/dax.c:227
Kernel panic - not syncing: panic_on_warn set ...

CPU: 0 PID: 12870 Comm: syz-executor3 Not tainted 4.19.0+ #87
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
Google 01/01/2011
Call Trace:
  __dump_stack lib/dump_stack.c:77 [inline]
  dump_stack+0x244/0x39d lib/dump_stack.c:113
  panic+0x238/0x4e7 kernel/panic.c:184
  __warn.cold.8+0x20/0x4a kernel/panic.c:536
  report_bug+0x254/0x2d0 lib/bug.c:186
  fixup_bug arch/x86/kernel/traps.c:178 [inline]
  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
  do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:966
RIP: 0010:get_unlocked_entry+0x3ac/0x4d0 fs/dax.c:227
Code: e8 31 ff 83 e0 01 48 89 c6 48 89 85 10 ff ff ff e8 09 18 96 ff 48 8b  
85 10 ff ff ff 48 85 c0 0f 85 34 fe ff ff e8 c4 16 96 ff <0f> 0b e8 bd 16  
96 ff 48 b8 00 00 00 00 00 fc ff df 48 03 85 f8 fe
RSP: 0018:ffff88018025e7b8 EFLAGS: 00010012
RAX: 0000000000040000 RBX: ffff88018025ead8 RCX: ffffc90008983000
RDX: 0000000000000341 RSI: ffffffff81e94d3c RDI: 0000000000000007
RBP: ffff88018025e8c8 R08: ffff88017f862280 R09: ffffed003004bd08
R10: ffffed003004bd08 R11: 0000000000000003 R12: dffffc0000000000
R13: ffffea0005e01040 R14: ffff88018025e800 R15: ffff88018025e8a0
  grab_mapping_entry fs/dax.c:447 [inline]
  dax_iomap_pte_fault.isra.35+0x8a5/0x37c0 fs/dax.c:1239
  dax_iomap_fault+0x51/0x70 fs/dax.c:1600
  ext4_dax_huge_fault+0x565/0x730 fs/ext4/file.c:320
  ext4_dax_fault+0x17/0x20 fs/ext4/file.c:341
  __do_fault+0x100/0x6b0 mm/memory.c:2991
  do_cow_fault mm/memory.c:3432 [inline]
  do_fault mm/memory.c:3531 [inline]
  handle_pte_fault mm/memory.c:3760 [inline]
  __handle_mm_fault+0x141b/0x5be0 mm/memory.c:3884
  handle_mm_fault+0x54f/0xc70 mm/memory.c:3921
  do_user_addr_fault arch/x86/mm/fault.c:1423 [inline]
  __do_page_fault+0x5e8/0xe60 arch/x86/mm/fault.c:1489
  do_page_fault+0xf2/0x7e0 arch/x86/mm/fault.c:1520
  page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1136
RIP: 0010:copy_user_generic_unrolled+0x89/0xc0  
arch/x86/lib/copy_user_64.S:66
Code: 38 4c 89 47 20 4c 89 4f 28 4c 89 57 30 4c 89 5f 38 48 8d 76 40 48 8d  
7f 40 ff c9 75 b6 89 d1 83 e2 07 c1 e9 03 74 12 4c 8b 06 <4c> 89 07 48 8d  
76 08 48 8d 7f 08 ff c9 75 ee 21 d2 74 10 89 d1 8a
RSP: 0018:ffff88018025f7d0 EFLAGS: 00010207
RAX: 0000000000000004 RBX: 000000000000001c RCX: 0000000000000003
RDX: 0000000000000004 RSI: ffff88018025fb40 RDI: 0000000020000000
RBP: ffff88018025f808 R08: 00000000000000b8 R09: ffffed003004bf68
R10: ffffed003004bf6b R11: 0000000000000003 R12: 000000002000001c
R13: 0000000020000000 R14: ffff88018025fb40 R15: 00007ffffffff000
  copy_to_user include/linux/uaccess.h:155 [inline]
  ext4_ioctl+0x3ed/0x44c0 fs/ext4/ioctl.c:1035
  vfs_ioctl fs/ioctl.c:46 [inline]
  file_ioctl fs/ioctl.c:501 [inline]
  do_vfs_ioctl+0x1de/0x1720 fs/ioctl.c:685
  ksys_ioctl+0xa9/0xd0 fs/ioctl.c:702
  __do_sys_ioctl fs/ioctl.c:709 [inline]
  __se_sys_ioctl fs/ioctl.c:707 [inline]
  __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:707
  do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
  entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457569
Code: fd b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7  
48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff  
ff 0f 83 cb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f0efb87dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457569
RDX: 0000000020000000 RSI: 00000000801c581f RDI: 0000000000000003
RBP: 000000000072c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f0efb87e6d4
R13: 00000000004bf929 R14: 00000000004cfa80 R15: 00000000ffffffff
Kernel Offset: disabled
Rebooting in 86400 seconds..


---
This bug is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzkaller@googlegroups.com.

syzbot will keep track of this bug report. See:
https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with  
syzbot.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: WARNING in get_unlocked_entry
  2018-10-30 15:00 WARNING in get_unlocked_entry syzbot
@ 2018-10-31  3:18 ` Matthew Wilcox
  2018-10-31  9:45   ` Dmitry Vyukov
  2018-10-31  9:46   ` Dmitry Vyukov
  0 siblings, 2 replies; 6+ messages in thread
From: Matthew Wilcox @ 2018-10-31  3:18 UTC (permalink / raw)
  To: syzbot; +Cc: jack, linux-fsdevel, linux-kernel, syzkaller-bugs, viro, zwisler

On Tue, Oct 30, 2018 at 08:00:03AM -0700, syzbot wrote:
> syzbot found the following crash on:
> 
> HEAD commit:    4b42745211af Merge tag 'armsoc-soc' of git://git.kernel.or..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=1187d06d400000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=93932074d01b4a5
> dashboard link: https://syzkaller.appspot.com/bug?extid=4fd0c066d82852499145
> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> 
> Unfortunately, I don't have any reproducer for this crash yet.

Hmmpf.  Would have been nice if syzbot had caught this during its tests
of the -next tree ...

> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+4fd0c066d82852499145@syzkaller.appspotmail.com
> 
> EXT4-fs (sda1): Cannot specify journal on remount
> EXT4-fs (sda1): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
> EXT4-fs (sda1): warning: refusing change of dax flag with busy inodes while
> remounting
> WARNING: CPU: 0 PID: 12870 at fs/dax.c:227 get_unlocked_entry+0x3ac/0x4d0
> fs/dax.c:227
> Kernel panic - not syncing: panic_on_warn set ...
> 
> CPU: 0 PID: 12870 Comm: syz-executor3 Not tainted 4.19.0+ #87
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
> Google 01/01/2011
> Call Trace:
>  __dump_stack lib/dump_stack.c:77 [inline]
>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>  panic+0x238/0x4e7 kernel/panic.c:184
>  __warn.cold.8+0x20/0x4a kernel/panic.c:536
>  report_bug+0x254/0x2d0 lib/bug.c:186
>  fixup_bug arch/x86/kernel/traps.c:178 [inline]
>  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
>  do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
>  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:966
> RIP: 0010:get_unlocked_entry+0x3ac/0x4d0 fs/dax.c:227
> Code: e8 31 ff 83 e0 01 48 89 c6 48 89 85 10 ff ff ff e8 09 18 96 ff 48 8b
> 85 10 ff ff ff 48 85 c0 0f 85 34 fe ff ff e8 c4 16 96 ff <0f> 0b e8 bd 16 96
> ff 48 b8 00 00 00 00 00 fc ff df 48 03 85 f8 fe
> RSP: 0018:ffff88018025e7b8 EFLAGS: 00010012
> RAX: 0000000000040000 RBX: ffff88018025ead8 RCX: ffffc90008983000
> RDX: 0000000000000341 RSI: ffffffff81e94d3c RDI: 0000000000000007
> RBP: ffff88018025e8c8 R08: ffff88017f862280 R09: ffffed003004bd08
> R10: ffffed003004bd08 R11: 0000000000000003 R12: dffffc0000000000
> R13: ffffea0005e01040 R14: ffff88018025e800 R15: ffff88018025e8a0
>  grab_mapping_entry fs/dax.c:447 [inline]

OK, so I'd like to know what value actually got loaded into 'entry'.
Maybe my x86-fu is weak, but I don't understand how this register dump
correlates with the instructions I'm seeing.

Here's the C code:

                entry = xas_load(xas);
                if (!entry || xa_is_internal(entry) ||
                                WARN_ON_ONCE(!xa_is_value(entry)) ||
                                !dax_is_locked(entry))
                        return entry;


I downloaded the .config that syzbot was using and built fs/dax.o.
Disassembling it, I get:

                                WARN_ON_ONCE(!xa_is_value(entry)) ||
    5e53:       31 ff                   xor    %edi,%edi
    5e55:       83 e0 01                and    $0x1,%eax
    5e58:       48 89 c6                mov    %rax,%rsi
    5e5b:       48 89 85 10 ff ff ff    mov    %rax,-0xf0(%rbp)
    5e62:       e8 00 00 00 00          callq  5e67 <get_unlocked_entry+0x397>
                        5e63: R_X86_64_PLT32    __sanitizer_cov_trace_const_cmp8
-0x4
    5e67:       48 8b 85 10 ff ff ff    mov    -0xf0(%rbp),%rax
    5e6e:       48 85 c0                test   %rax,%rax
    5e71:       0f 85 34 fe ff ff       jne    5cab <get_unlocked_entry+0x1db>
    5e77:       e8 00 00 00 00          callq  5e7c <get_unlocked_entry+0x3ac>
                        5e78: R_X86_64_PLT32    __sanitizer_cov_trace_pc-0x4
    5e7c:       0f 0b                   ud2    

That ud2 is the WARN_ON trigger.  It's at offset 0x3ac from the start of
get_unlocked_entry() so it matches the dump.

The key is 'test %rax,%rax' at 5e6e.  If that passes, we jump to 5cab
where we do xa_to_value() in order to implement dax_is_locked().  So is
'entry' actually 0x0000000000040000 like the dump says?

That's where I get confused.  The previous insn (5e67) loads rax from what
I presume is the stack, having previously stored it there at insn 535b.
But insn 5e51 should have reduced %rax to just 0 or 1 in the low bit of
the register.  So clearly I have my understanding of x86 insns confused.
If someone could help me out here, I'd be grateful.


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: WARNING in get_unlocked_entry
  2018-10-31  3:18 ` Matthew Wilcox
@ 2018-10-31  9:45   ` Dmitry Vyukov
  2018-10-31  9:46   ` Dmitry Vyukov
  1 sibling, 0 replies; 6+ messages in thread
From: Dmitry Vyukov @ 2018-10-31  9:45 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: syzbot, Jan Kara, linux-fsdevel, LKML, syzkaller-bugs, Al Viro, zwisler

On Wed, Oct 31, 2018 at 4:18 AM, Matthew Wilcox <willy@infradead.org> wrote:
> On Tue, Oct 30, 2018 at 08:00:03AM -0700, syzbot wrote:
>> syzbot found the following crash on:
>>
>> HEAD commit:    4b42745211af Merge tag 'armsoc-soc' of git://git.kernel.or..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1187d06d400000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=93932074d01b4a5
>> dashboard link: https://syzkaller.appspot.com/bug?extid=4fd0c066d82852499145
>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
>
> Hmmpf.  Would have been nice if syzbot had caught this during its tests
> of the -next tree ...
>
>> IMPORTANT: if you fix the bug, please add the following tag to the commit:
>> Reported-by: syzbot+4fd0c066d82852499145@syzkaller.appspotmail.com
>>
>> EXT4-fs (sda1): Cannot specify journal on remount
>> EXT4-fs (sda1): DAX enabled. Warning: EXPERIMENTAL, use at your own risk
>> EXT4-fs (sda1): warning: refusing change of dax flag with busy inodes while
>> remounting
>> WARNING: CPU: 0 PID: 12870 at fs/dax.c:227 get_unlocked_entry+0x3ac/0x4d0
>> fs/dax.c:227
>> Kernel panic - not syncing: panic_on_warn set ...
>>
>> CPU: 0 PID: 12870 Comm: syz-executor3 Not tainted 4.19.0+ #87
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
>> Google 01/01/2011
>> Call Trace:
>>  __dump_stack lib/dump_stack.c:77 [inline]
>>  dump_stack+0x244/0x39d lib/dump_stack.c:113
>>  panic+0x238/0x4e7 kernel/panic.c:184
>>  __warn.cold.8+0x20/0x4a kernel/panic.c:536
>>  report_bug+0x254/0x2d0 lib/bug.c:186
>>  fixup_bug arch/x86/kernel/traps.c:178 [inline]
>>  do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:271
>>  do_invalid_op+0x36/0x40 arch/x86/kernel/traps.c:290
>>  invalid_op+0x14/0x20 arch/x86/entry/entry_64.S:966
>> RIP: 0010:get_unlocked_entry+0x3ac/0x4d0 fs/dax.c:227
>> Code: e8 31 ff 83 e0 01 48 89 c6 48 89 85 10 ff ff ff e8 09 18 96 ff 48 8b
>> 85 10 ff ff ff 48 85 c0 0f 85 34 fe ff ff e8 c4 16 96 ff <0f> 0b e8 bd 16 96
>> ff 48 b8 00 00 00 00 00 fc ff df 48 03 85 f8 fe
>> RSP: 0018:ffff88018025e7b8 EFLAGS: 00010012
>> RAX: 0000000000040000 RBX: ffff88018025ead8 RCX: ffffc90008983000
>> RDX: 0000000000000341 RSI: ffffffff81e94d3c RDI: 0000000000000007
>> RBP: ffff88018025e8c8 R08: ffff88017f862280 R09: ffffed003004bd08
>> R10: ffffed003004bd08 R11: 0000000000000003 R12: dffffc0000000000
>> R13: ffffea0005e01040 R14: ffff88018025e800 R15: ffff88018025e8a0
>>  grab_mapping_entry fs/dax.c:447 [inline]
>
> OK, so I'd like to know what value actually got loaded into 'entry'.
> Maybe my x86-fu is weak, but I don't understand how this register dump
> correlates with the instructions I'm seeing.
>
> Here's the C code:
>
>                 entry = xas_load(xas);
>                 if (!entry || xa_is_internal(entry) ||
>                                 WARN_ON_ONCE(!xa_is_value(entry)) ||
>                                 !dax_is_locked(entry))
>                         return entry;
>
>
> I downloaded the .config that syzbot was using and built fs/dax.o.
> Disassembling it, I get:
>
>                                 WARN_ON_ONCE(!xa_is_value(entry)) ||
>     5e53:       31 ff                   xor    %edi,%edi
>     5e55:       83 e0 01                and    $0x1,%eax
>     5e58:       48 89 c6                mov    %rax,%rsi
>     5e5b:       48 89 85 10 ff ff ff    mov    %rax,-0xf0(%rbp)
>     5e62:       e8 00 00 00 00          callq  5e67 <get_unlocked_entry+0x397>
>                         5e63: R_X86_64_PLT32    __sanitizer_cov_trace_const_cmp8
> -0x4
>     5e67:       48 8b 85 10 ff ff ff    mov    -0xf0(%rbp),%rax
>     5e6e:       48 85 c0                test   %rax,%rax
>     5e71:       0f 85 34 fe ff ff       jne    5cab <get_unlocked_entry+0x1db>
>     5e77:       e8 00 00 00 00          callq  5e7c <get_unlocked_entry+0x3ac>
>                         5e78: R_X86_64_PLT32    __sanitizer_cov_trace_pc-0x4
>     5e7c:       0f 0b                   ud2
>
> That ud2 is the WARN_ON trigger.  It's at offset 0x3ac from the start of
> get_unlocked_entry() so it matches the dump.
>
> The key is 'test %rax,%rax' at 5e6e.  If that passes, we jump to 5cab
> where we do xa_to_value() in order to implement dax_is_locked().  So is
> 'entry' actually 0x0000000000040000 like the dump says?
>
> That's where I get confused.  The previous insn (5e67) loads rax from what
> I presume is the stack, having previously stored it there at insn 535b.
> But insn 5e51 should have reduced %rax to just 0 or 1 in the low bit of
> the register.  So clearly I have my understanding of x86 insns confused.
> If someone could help me out here, I'd be grateful.

There is a call to __sanitizer_cov_trace_pc before ud2 and rax is not
a caller-preserved register. So I think we can just assume that
xa_is_value returned 0.

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: WARNING in get_unlocked_entry
  2018-10-31  3:18 ` Matthew Wilcox
  2018-10-31  9:45   ` Dmitry Vyukov
@ 2018-10-31  9:46   ` Dmitry Vyukov
  2018-10-31 19:18     ` Matthew Wilcox
  1 sibling, 1 reply; 6+ messages in thread
From: Dmitry Vyukov @ 2018-10-31  9:46 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: syzbot, Jan Kara, linux-fsdevel, LKML, syzkaller-bugs, Al Viro, zwisler

On Wed, Oct 31, 2018 at 4:18 AM, Matthew Wilcox <willy@infradead.org> wrote:
> On Tue, Oct 30, 2018 at 08:00:03AM -0700, syzbot wrote:
>> syzbot found the following crash on:
>>
>> HEAD commit:    4b42745211af Merge tag 'armsoc-soc' of git://git.kernel.or..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=1187d06d400000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=93932074d01b4a5
>> dashboard link: https://syzkaller.appspot.com/bug?extid=4fd0c066d82852499145
>> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>>
>> Unfortunately, I don't have any reproducer for this crash yet.
>
> Hmmpf.  Would have been nice if syzbot had caught this during its tests
> of the -next tree ...

What -next tree do you mean? If it satisfies the criteria we can add it:
https://github.com/google/syzkaller/issues/592

^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: WARNING in get_unlocked_entry
  2018-10-31  9:46   ` Dmitry Vyukov
@ 2018-10-31 19:18     ` Matthew Wilcox
  2018-10-31 19:20       ` Dmitry Vyukov
  0 siblings, 1 reply; 6+ messages in thread
From: Matthew Wilcox @ 2018-10-31 19:18 UTC (permalink / raw)
  To: Dmitry Vyukov
  Cc: syzbot, Jan Kara, linux-fsdevel, LKML, syzkaller-bugs, Al Viro, zwisler

On Wed, Oct 31, 2018 at 10:46:19AM +0100, Dmitry Vyukov wrote:
> On Wed, Oct 31, 2018 at 4:18 AM, Matthew Wilcox <willy@infradead.org> wrote:
> > On Tue, Oct 30, 2018 at 08:00:03AM -0700, syzbot wrote:
> >> syzbot found the following crash on:
> >>
> >> HEAD commit:    4b42745211af Merge tag 'armsoc-soc' of git://git.kernel.or..
> >> git tree:       upstream
> >> console output: https://syzkaller.appspot.com/x/log.txt?x=1187d06d400000
> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=93932074d01b4a5
> >> dashboard link: https://syzkaller.appspot.com/bug?extid=4fd0c066d82852499145
> >> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
> >>
> >> Unfortunately, I don't have any reproducer for this crash yet.
> >
> > Hmmpf.  Would have been nice if syzbot had caught this during its tests
> > of the -next tree ...
> 
> What -next tree do you mean? If it satisfies the criteria we can add it:
> https://github.com/google/syzkaller/issues/592

I meant linux-next, as in the merge of everybody's -next trees.  Reading
that bug, it seems outside your scope for now ;-(


^ permalink raw reply	[flat|nested] 6+ messages in thread

* Re: WARNING in get_unlocked_entry
  2018-10-31 19:18     ` Matthew Wilcox
@ 2018-10-31 19:20       ` Dmitry Vyukov
  0 siblings, 0 replies; 6+ messages in thread
From: Dmitry Vyukov @ 2018-10-31 19:20 UTC (permalink / raw)
  To: Matthew Wilcox
  Cc: syzbot, Jan Kara, linux-fsdevel, LKML, syzkaller-bugs, Al Viro, zwisler

On Wed, Oct 31, 2018 at 8:18 PM, Matthew Wilcox <willy@infradead.org> wrote:
> On Wed, Oct 31, 2018 at 10:46:19AM +0100, Dmitry Vyukov wrote:
>> On Wed, Oct 31, 2018 at 4:18 AM, Matthew Wilcox <willy@infradead.org> wrote:
>> > On Tue, Oct 30, 2018 at 08:00:03AM -0700, syzbot wrote:
>> >> syzbot found the following crash on:
>> >>
>> >> HEAD commit:    4b42745211af Merge tag 'armsoc-soc' of git://git.kernel.or..
>> >> git tree:       upstream
>> >> console output: https://syzkaller.appspot.com/x/log.txt?x=1187d06d400000
>> >> kernel config:  https://syzkaller.appspot.com/x/.config?x=93932074d01b4a5
>> >> dashboard link: https://syzkaller.appspot.com/bug?extid=4fd0c066d82852499145
>> >> compiler:       gcc (GCC) 8.0.1 20180413 (experimental)
>> >>
>> >> Unfortunately, I don't have any reproducer for this crash yet.
>> >
>> > Hmmpf.  Would have been nice if syzbot had caught this during its tests
>> > of the -next tree ...
>>
>> What -next tree do you mean? If it satisfies the criteria we can add it:
>> https://github.com/google/syzkaller/issues/592
>
> I meant linux-next, as in the merge of everybody's -next trees.  Reading
> that bug, it seems outside your scope for now ;-(


We do test linux-next:
https://syzkaller.appspot.com/#managers
But this crash happened only once across all trees and machines. So it
just looks too elusive (subtle race?) to be reliably spotted in
linux-next.

^ permalink raw reply	[flat|nested] 6+ messages in thread

end of thread, other threads:[~2018-10-31 19:21 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2018-10-30 15:00 WARNING in get_unlocked_entry syzbot
2018-10-31  3:18 ` Matthew Wilcox
2018-10-31  9:45   ` Dmitry Vyukov
2018-10-31  9:46   ` Dmitry Vyukov
2018-10-31 19:18     ` Matthew Wilcox
2018-10-31 19:20       ` Dmitry Vyukov

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