Re: possible deadlock in __do_page_fault

[Joel Fernandes <joel@joelfernandes.org>]

On Thu, Sep 20, 2018 at 5:12 PM Todd Kjos <tkjos@google.com> wrote:
>
> +Joel Fernandes
>
> On Thu, Sep 20, 2018 at 2:11 PM Andrew Morton <akpm@linux-foundation.org> wrote:
> >
> >
> > Thanks.  Let's cc the ashmem folks.
> >

This should be fixed by https://patchwork.kernel.org/patch/10572477/

It has Neil Brown's Reviewed-by but looks like didn't yet appear in
anyone's tree, could Greg take this patch?

thanks,

 - Joel



> > On Thu, 20 Sep 2018 14:04:05 -0700 syzbot <syzbot+a76129f18c89f3e2ddd4@syzkaller.appspotmail.com> wrote:
> >
> > > Hello,
> > >
> > > syzbot found the following crash on:
> > >
> > > HEAD commit:    a0cb0cabe4bb Add linux-next specific files for 20180920
> > > git tree:       linux-next
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=15139721400000
> > > kernel config:  https://syzkaller.appspot.com/x/.config?x=786006c5dafbadf6
> > > dashboard link: https://syzkaller.appspot.com/bug?extid=a76129f18c89f3e2ddd4
> > > 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+a76129f18c89f3e2ddd4@syzkaller.appspotmail.com
> > >
> > >
> > > ======================================================
> > > WARNING: possible circular locking dependency detected
> > > 4.19.0-rc4-next-20180920+ #76 Not tainted
> > > ------------------------------------------------------
> > > syz-executor3/21327 is trying to acquire lock:
> > > 000000009bc5286f (&mm->mmap_sem){++++}, at: __do_page_fault+0xb61/0xec0
> > > arch/x86/mm/fault.c:1333
> > >
> > > but task is already holding lock:
> > > 00000000a2c51c08 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_lock
> > > include/linux/fs.h:745 [inline]
> > > 00000000a2c51c08 (&sb->s_type->i_mutex_key#10){+.+.}, at:
> > > generic_file_write_iter+0xed/0x870 mm/filemap.c:3304
> > >
> > > which lock already depends on the new lock.
> > >
> > >
> > > the existing dependency chain (in reverse order) is:
> > >
> > > -> #2 (&sb->s_type->i_mutex_key#10){+.+.}:
> > >         down_write+0x8a/0x130 kernel/locking/rwsem.c:70
> > >         inode_lock include/linux/fs.h:745 [inline]
> > >         shmem_fallocate+0x18b/0x12c0 mm/shmem.c:2651
> > >         ashmem_shrink_scan+0x238/0x660 drivers/staging/android/ashmem.c:455
> > >         ashmem_ioctl+0x3ae/0x13a0 drivers/staging/android/ashmem.c:797
> > >         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
> > >
> > > -> #1 (ashmem_mutex){+.+.}:
> > >         __mutex_lock_common kernel/locking/mutex.c:925 [inline]
> > >         __mutex_lock+0x166/0x1700 kernel/locking/mutex.c:1072
> > >         mutex_lock_nested+0x16/0x20 kernel/locking/mutex.c:1087
> > >         ashmem_mmap+0x55/0x520 drivers/staging/android/ashmem.c:361
> > >         call_mmap include/linux/fs.h:1830 [inline]
> > >         mmap_region+0xe82/0x1cd0 mm/mmap.c:1762
> > >         do_mmap+0xa10/0x1220 mm/mmap.c:1535
> > >         do_mmap_pgoff include/linux/mm.h:2298 [inline]
> > >         vm_mmap_pgoff+0x213/0x2c0 mm/util.c:357
> > >         ksys_mmap_pgoff+0x4da/0x660 mm/mmap.c:1585
> > >         __do_sys_mmap arch/x86/kernel/sys_x86_64.c:100 [inline]
> > >         __se_sys_mmap arch/x86/kernel/sys_x86_64.c:91 [inline]
> > >         __x64_sys_mmap+0xe9/0x1b0 arch/x86/kernel/sys_x86_64.c:91
> > >         do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> > >         entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > >
> > > -> #0 (&mm->mmap_sem){++++}:
> > >         lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
> > >         down_read+0x8d/0x120 kernel/locking/rwsem.c:24
> > >         __do_page_fault+0xb61/0xec0 arch/x86/mm/fault.c:1333
> > >         do_page_fault+0xed/0x7d1 arch/x86/mm/fault.c:1472
> > >         page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1139
> > >         fault_in_pages_readable include/linux/pagemap.h:601 [inline]
> > >         iov_iter_fault_in_readable+0x1b4/0x450 lib/iov_iter.c:421
> > >         generic_perform_write+0x216/0x6a0 mm/filemap.c:3144
> > >         __generic_file_write_iter+0x26e/0x630 mm/filemap.c:3279
> > >         generic_file_write_iter+0x436/0x870 mm/filemap.c:3307
> > >         call_write_iter include/linux/fs.h:1825 [inline]
> > >         do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680
> > >         do_iter_write+0x185/0x5f0 fs/read_write.c:959
> > >         vfs_writev+0x1f1/0x360 fs/read_write.c:1004
> > >         do_pwritev+0x1cc/0x280 fs/read_write.c:1093
> > >         __do_sys_pwritev fs/read_write.c:1140 [inline]
> > >         __se_sys_pwritev fs/read_write.c:1135 [inline]
> > >         __x64_sys_pwritev+0x9a/0xf0 fs/read_write.c:1135
> > >         do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> > >         entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > >
> > > other info that might help us debug this:
> > >
> > > Chain exists of:
> > >    &mm->mmap_sem --> ashmem_mutex --> &sb->s_type->i_mutex_key#10
> > >
> > >   Possible unsafe locking scenario:
> > >
> > >         CPU0                    CPU1
> > >         ----                    ----
> > >    lock(&sb->s_type->i_mutex_key#10);
> > >                                 lock(ashmem_mutex);
> > >                                 lock(&sb->s_type->i_mutex_key#10);
> > >    lock(&mm->mmap_sem);
> > >
> > >   *** DEADLOCK ***
> > >
> > > 2 locks held by syz-executor3/21327:
> > >   #0: 000000003de4eab1 (sb_writers#3){.+.+}, at: file_start_write
> > > include/linux/fs.h:2784 [inline]
> > >   #0: 000000003de4eab1 (sb_writers#3){.+.+}, at: vfs_writev+0x2bd/0x360
> > > fs/read_write.c:1003
> > >   #1: 00000000a2c51c08 (&sb->s_type->i_mutex_key#10){+.+.}, at: inode_lock
> > > include/linux/fs.h:745 [inline]
> > >   #1: 00000000a2c51c08 (&sb->s_type->i_mutex_key#10){+.+.}, at:
> > > generic_file_write_iter+0xed/0x870 mm/filemap.c:3304
> > >
> > > stack backtrace:
> > > CPU: 1 PID: 21327 Comm: syz-executor3 Not tainted 4.19.0-rc4-next-20180920+
> > > #76
> > > 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+0x1d3/0x2c4 lib/dump_stack.c:113
> > >   print_circular_bug.isra.33.cold.54+0x1bd/0x27d
> > > kernel/locking/lockdep.c:1221
> > >   check_prev_add kernel/locking/lockdep.c:1861 [inline]
> > >   check_prevs_add kernel/locking/lockdep.c:1974 [inline]
> > >   validate_chain kernel/locking/lockdep.c:2415 [inline]
> > >   __lock_acquire+0x33e4/0x4ec0 kernel/locking/lockdep.c:3411
> > >   lock_acquire+0x1ed/0x520 kernel/locking/lockdep.c:3900
> > >   down_read+0x8d/0x120 kernel/locking/rwsem.c:24
> > >   __do_page_fault+0xb61/0xec0 arch/x86/mm/fault.c:1333
> > >   do_page_fault+0xed/0x7d1 arch/x86/mm/fault.c:1472
> > >   page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1139
> > > RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:601 [inline]
> > > RIP: 0010:iov_iter_fault_in_readable+0x1b4/0x450 lib/iov_iter.c:421
> > > Code: fd 49 39 dc 76 17 eb 3c e8 e9 a0 ef fd 49 81 c4 00 10 00 00 4c 39 a5
> > > 28 ff ff ff 72 2e e8 d4 a0 ef fd 0f 1f 00 0f ae e8 31 db <41> 8a 04 24 0f
> > > 1f 00 31 ff 89 de 88 85 58 ff ff ff e8 c6 a1 ef fd
> > > RSP: 0018:ffff88018dfe7650 EFLAGS: 00010246
> > > RAX: 0000000000040000 RBX: 0000000000000000 RCX: ffffc90005662000
> > > RDX: 00000000000001c2 RSI: ffffffff838daf1c RDI: 0000000000000005
> > > RBP: ffff88018dfe7728 R08: ffff880198ad2240 R09: ffffed00319dc039
> > > R10: ffffed00319dc039 R11: ffff88018cee01cb R12: 0000000020012000
> > > R13: 0000000000000001 R14: 0000000000000001 R15: ffff88018dfe7c50
> > >   generic_perform_write+0x216/0x6a0 mm/filemap.c:3144
> > >   __generic_file_write_iter+0x26e/0x630 mm/filemap.c:3279
> > >   generic_file_write_iter+0x436/0x870 mm/filemap.c:3307
> > >   call_write_iter include/linux/fs.h:1825 [inline]
> > >   do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680
> > >   do_iter_write+0x185/0x5f0 fs/read_write.c:959
> > >   vfs_writev+0x1f1/0x360 fs/read_write.c:1004
> > >   do_pwritev+0x1cc/0x280 fs/read_write.c:1093
> > >   __do_sys_pwritev fs/read_write.c:1140 [inline]
> > >   __se_sys_pwritev fs/read_write.c:1135 [inline]
> > >   __x64_sys_pwritev+0x9a/0xf0 fs/read_write.c:1135
> > >   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> > >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > > RIP: 0033:0x457679
> > > Code: 1d b4 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > RSP: 002b:00007f96ef162c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000128
> > > RAX: ffffffffffffffda RBX: 00007f96ef1636d4 RCX: 0000000000457679
> > > RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000004
> > > RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
> > > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> > > R13: 00000000004d4a88 R14: 00000000004c31d4 R15: 0000000000000000
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > FAULT_FLAG_ALLOW_RETRY missing 30
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > CPU: 1 PID: 21327 Comm: syz-executor3 Not tainted 4.19.0-rc4-next-20180920+
> > > #76
> > > 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+0x1d3/0x2c4 lib/dump_stack.c:113
> > >   handle_userfault.cold.33+0x47/0x62 fs/userfaultfd.c:432
> > >   do_anonymous_page mm/memory.c:2915 [inline]
> > >   handle_pte_fault mm/memory.c:3732 [inline]
> > >   __handle_mm_fault+0x45ed/0x53e0 mm/memory.c:3858
> > >   handle_mm_fault+0x54f/0xc70 mm/memory.c:3895
> > >   __do_page_fault+0x673/0xec0 arch/x86/mm/fault.c:1397
> > >   do_page_fault+0xed/0x7d1 arch/x86/mm/fault.c:1472
> > >   page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1139
> > > RIP: 0010:fault_in_pages_readable include/linux/pagemap.h:601 [inline]
> > > RIP: 0010:iov_iter_fault_in_readable+0x1b4/0x450 lib/iov_iter.c:421
> > > Code: fd 49 39 dc 76 17 eb 3c e8 e9 a0 ef fd 49 81 c4 00 10 00 00 4c 39 a5
> > > 28 ff ff ff 72 2e e8 d4 a0 ef fd 0f 1f 00 0f ae e8 31 db <41> 8a 04 24 0f
> > > 1f 00 31 ff 89 de 88 85 58 ff ff ff e8 c6 a1 ef fd
> > > RSP: 0018:ffff88018dfe7650 EFLAGS: 00010246
> > > RAX: 0000000000040000 RBX: 0000000000000000 RCX: ffffc90005662000
> > > RDX: 00000000000001c2 RSI: ffffffff838daf1c RDI: 0000000000000005
> > > RBP: ffff88018dfe7728 R08: ffff880198ad2240 R09: ffffed00319dc039
> > > R10: ffffed00319dc039 R11: ffff88018cee01cb R12: 0000000020012000
> > > R13: 0000000000000001 R14: 0000000000000001 R15: ffff88018dfe7c50
> > >   generic_perform_write+0x216/0x6a0 mm/filemap.c:3144
> > >   __generic_file_write_iter+0x26e/0x630 mm/filemap.c:3279
> > >   generic_file_write_iter+0x436/0x870 mm/filemap.c:3307
> > >   call_write_iter include/linux/fs.h:1825 [inline]
> > >   do_iter_readv_writev+0x8b0/0xa80 fs/read_write.c:680
> > >   do_iter_write+0x185/0x5f0 fs/read_write.c:959
> > >   vfs_writev+0x1f1/0x360 fs/read_write.c:1004
> > >   do_pwritev+0x1cc/0x280 fs/read_write.c:1093
> > >   __do_sys_pwritev fs/read_write.c:1140 [inline]
> > >   __se_sys_pwritev fs/read_write.c:1135 [inline]
> > >   __x64_sys_pwritev+0x9a/0xf0 fs/read_write.c:1135
> > >   do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
> > >   entry_SYSCALL_64_after_hwframe+0x49/0xbe
> > > RIP: 0033:0x457679
> > > Code: 1d b4 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 eb b3 fb ff c3 66 2e 0f 1f 84 00 00 00 00
> > > RSP: 002b:00007f96ef162c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000128
> > > RAX: ffffffffffffffda RBX: 00007f96ef1636d4 RCX: 0000000000457679
> > > RDX: 0000000000000001 RSI: 0000000020000000 RDI: 0000000000000004
> > > RBP: 000000000072bf00 R08: 0000000000000000 R09: 0000000000000000
> > > R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
> > > R13: 00000000004d4a88 R14: 00000000004c31d4 R15: 0000000000000000
> > > kobject: 'loop4' (000000004119f3b1): kobject_uevent_env
> > > kobject: 'loop4' (000000004119f3b1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop4'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop4' (000000004119f3b1): kobject_uevent_env
> > > kobject: 'loop4' (000000004119f3b1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop4'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop4' (000000004119f3b1): kobject_uevent_env
> > > kobject: 'loop4' (000000004119f3b1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop4'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop4' (000000004119f3b1): kobject_uevent_env
> > > kobject: 'loop4' (000000004119f3b1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop4'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop4' (000000004119f3b1): kobject_uevent_env
> > > kobject: 'loop4' (000000004119f3b1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop4'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop4' (000000004119f3b1): kobject_uevent_env
> > > kobject: 'loop4' (000000004119f3b1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop4'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > audit: type=1326 audit(2000000012.020:46): auid=4294967295 uid=0 gid=0
> > > ses=4294967295 subj==unconfined pid=21534 comm="syz-executor0"
> > > exe="/root/syz-executor0" sig=31 arch=c000003e syscall=202 compat=0
> > > ip=0x457679 code=0x0
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > audit: type=1326 audit(2000000012.950:47): auid=4294967295 uid=0 gid=0
> > > ses=4294967295 subj==unconfined pid=21566 comm="syz-executor0"
> > > exe="/root/syz-executor0" sig=31 arch=c000003e syscall=202 compat=0
> > > ip=0x457679 code=0x0
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop2' (00000000dc629c38): kobject_uevent_env
> > > kobject: 'loop2' (00000000dc629c38): fill_kobj_path: path
> > > = '/devices/virtual/block/loop2'
> > > kobject: 'loop3' (00000000aff594d4): kobject_uevent_env
> > > kobject: 'loop3' (00000000aff594d4): fill_kobj_path: path
> > > = '/devices/virtual/block/loop3'
> > > kobject: 'loop4' (000000004119f3b1): kobject_uevent_env
> > > kobject: 'loop4' (000000004119f3b1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop4'
> > > audit: type=1326 audit(2000000013.460:48): auid=4294967295 uid=0 gid=0
> > > ses=4294967295 subj==unconfined pid=21585 comm="syz-executor4"
> > > exe="/root/syz-executor4" sig=31 arch=c000003e syscall=202 compat=0
> > > ip=0x457679 code=0x0
> > > audit: type=1326 audit(2000000013.510:49): auid=4294967295 uid=0 gid=0
> > > ses=4294967295 subj==unconfined pid=21588 comm="syz-executor2"
> > > exe="/root/syz-executor2" sig=31 arch=c000003e syscall=202 compat=0
> > > ip=0x457679 code=0x0
> > > kobject: 'loop1' (00000000980d23a1): kobject_uevent_env
> > > kobject: 'loop1' (00000000980d23a1): fill_kobj_path: path
> > > = '/devices/virtual/block/loop1'
> > > kobject: 'loop0' (00000000ee0adfaf): kobject_uevent_env
> > > kobject: 'loop0' (00000000ee0adfaf): fill_kobj_path: path
> > > = '/devices/virtual/block/loop0'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > audit: type=1326 audit(2000000013.800:50): auid=4294967295 uid=0 gid=0
> > > ses=4294967295 subj==unconfined pid=21601 comm="syz-executor0"
> > > exe="/root/syz-executor0" sig=31 arch=c000003e syscall=202 compat=0
> > > ip=0x457679 code=0x0
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > > kobject: 'loop5' (00000000699d1086): kobject_uevent_env
> > > kobject: 'loop5' (00000000699d1086): fill_kobj_path: path
> > > = '/devices/virtual/block/loop5'
> > >
> > >
> > > ---
> > > 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.