Hello,
syzbot found the following issue on:
HEAD commit: bbed346d5a96 Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=157dc905880000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
dashboard link: https://syzkaller.appspot.com/bug?extid=52bf723c703aa9b88640
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17179651880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10cc5d91880000
Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e8e91bc79312/disk-bbed346d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c1cb3fb3b77e/vmlinux-bbed346d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/3bd548b7efd3/mount_0.gz
IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1)
WARNING: CPU: 1 PID: 3031 at kernel/locking/lockdep.c:231 check_wait_context kernel/locking/lockdep.c:4727 [inline]
WARNING: CPU: 1 PID: 3031 at kernel/locking/lockdep.c:231 __lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
Modules linked in:
CPU: 1 PID: 3031 Comm: syz-executor196 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : check_wait_context kernel/locking/lockdep.c:4727 [inline]
pc : __lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
lr : hlock_class kernel/locking/lockdep.c:231 [inline]
lr : check_wait_context kernel/locking/lockdep.c:4727 [inline]
lr : __lock_acquire+0x298/0x30a4 kernel/locking/lockdep.c:5003
sp : ffff8000129f3900
x29: ffff8000129f39e0 x28: 0000000000000001 x27: ffff0000c5371aa8
x26: ffff80000cb49def x25: ffff0000c53724d8 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000001 x21: 0000000000000000
x20: 0000000000000000 x19: 55f07fe0846faa84 x18: 00000000000003e8
x17: ffff80000bffd6bc x16: ffff80000db49158 x15: ffff0000c5371a80
x14: 0000000000000000 x13: 0000000000000012 x12: ffff80000d5ef920
x11: ff808000081c0d5c x10: ffff80000dd0b198 x9 : 62dca878cb47c300
x8 : 0000000000000000 x7 : 4e5241575f534b43 x6 : ffff80000819545c
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000100000001 x0 : 0000000000000016
Call trace:
check_wait_context kernel/locking/lockdep.c:4727 [inline]
__lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:349 [inline]
nilfs_palloc_clear_cache fs/nilfs2/alloc.c:848 [inline]
nilfs_palloc_destroy_cache+0x2c/0xb8 fs/nilfs2/alloc.c:860
nilfs_mdt_clear+0x34/0x70 fs/nilfs2/mdt.c:478
nilfs_clear_inode+0x64/0x140 fs/nilfs2/inode.c:886
nilfs_evict_inode+0x68/0x1cc fs/nilfs2/inode.c:908
evict+0xec/0x334 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput+0x2c4/0x324 fs/inode.c:1774
nilfs_put_super+0x6c/0x9c fs/nilfs2/super.c:476
generic_shutdown_super+0x8c/0x190 fs/super.c:491
kill_block_super+0x30/0x78 fs/super.c:1427
deactivate_locked_super+0x70/0xe8 fs/super.c:332
deactivate_super+0xd0/0xd4 fs/super.c:363
cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186
__cleanup_mnt+0x20/0x30 fs/namespace.c:1193
task_work_run+0xc4/0x14c kernel/task_work.c:177
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
irq event stamp: 356107
hardirqs last enabled at (356107): [<ffff80000bfc8a34>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
hardirqs last enabled at (356107): [<ffff80000bfc8a34>] _raw_spin_unlock_irq+0x3c/0x70 kernel/locking/spinlock.c:202
hardirqs last disabled at (356106): [<ffff80000bfc8834>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline]
hardirqs last disabled at (356106): [<ffff80000bfc8834>] _raw_spin_lock_irq+0x34/0x9c kernel/locking/spinlock.c:170
softirqs last enabled at (355348): [<ffff80000801c33c>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (355346): [<ffff80000801c308>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---
Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b8
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000004
CM = 0, WnR = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=000000010ae77000
[00000000000000b8] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 3031 Comm: syz-executor196 Tainted: G W 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : check_wait_context kernel/locking/lockdep.c:4727 [inline]
pc : __lock_acquire+0x2d0/0x30a4 kernel/locking/lockdep.c:5003
lr : hlock_class kernel/locking/lockdep.c:231 [inline]
lr : check_wait_context kernel/locking/lockdep.c:4727 [inline]
lr : __lock_acquire+0x298/0x30a4 kernel/locking/lockdep.c:5003
sp : ffff8000129f3900
x29: ffff8000129f39e0 x28: 0000000000000001 x27: ffff0000c5371aa8
x26: ffff80000cb49def x25: ffff0000c53724d8 x24: 0000000000000000
x23: 0000000000000000 x22: 0000000000000001 x21: 0000000000000000
x20: 0000000000000000 x19: 55f07fe0846faa84 x18: 00000000000003e8
x17: ffff80000bffd6bc x16: ffff80000db49158 x15: ffff0000c5371a80
x14: 0000000000000000 x13: 0000000000000012 x12: ffff80000d5ef920
x11: ff808000081c0d5c x10: ffff80000dd0b198 x9 : 0000000000040a84
x8 : 0000000000000000 x7 : 4e5241575f534b43 x6 : ffff80000819545c
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000100000001 x0 : 0000000000000016
Call trace:
hlock_class kernel/locking/lockdep.c:222 [inline]
check_wait_context kernel/locking/lockdep.c:4728 [inline]
__lock_acquire+0x2d0/0x30a4 kernel/locking/lockdep.c:5003
lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
spin_lock include/linux/spinlock.h:349 [inline]
nilfs_palloc_clear_cache fs/nilfs2/alloc.c:848 [inline]
nilfs_palloc_destroy_cache+0x2c/0xb8 fs/nilfs2/alloc.c:860
nilfs_mdt_clear+0x34/0x70 fs/nilfs2/mdt.c:478
nilfs_clear_inode+0x64/0x140 fs/nilfs2/inode.c:886
nilfs_evict_inode+0x68/0x1cc fs/nilfs2/inode.c:908
evict+0xec/0x334 fs/inode.c:665
iput_final fs/inode.c:1748 [inline]
iput+0x2c4/0x324 fs/inode.c:1774
nilfs_put_super+0x6c/0x9c fs/nilfs2/super.c:476
generic_shutdown_super+0x8c/0x190 fs/super.c:491
kill_block_super+0x30/0x78 fs/super.c:1427
deactivate_locked_super+0x70/0xe8 fs/super.c:332
deactivate_super+0xd0/0xd4 fs/super.c:363
cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186
__cleanup_mnt+0x20/0x30 fs/namespace.c:1193
task_work_run+0xc4/0x14c kernel/task_work.c:177
resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:637
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
Code: b002db8a 91056210 9106614a b9400329 (3942e114)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: b002db8a adrp x10, 0x5b71000
4: 91056210 add x16, x16, #0x158
8: 9106614a add x10, x10, #0x198
c: b9400329 ldr w9, [x25]
* 10: 3942e114 ldrb w20, [x8, #184] <-- trapping instruction
---
This report 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 [email protected].
syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
syzbot can test patches for this issue, for details see:
https://goo.gl/tpsmEJ#testing-patches
On Mon, Nov 7, 2022 at 2:02 AM syzbot wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: bbed346d5a96 Merge branch 'for-next/core' into for-kernelci
> git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
> console output: https://syzkaller.appspot.com/x/log.txt?x=157dc905880000
> kernel config: https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
> dashboard link: https://syzkaller.appspot.com/bug?extid=52bf723c703aa9b88640
> compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
> userspace arch: arm64
> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=17179651880000
> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10cc5d91880000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/e8e91bc79312/disk-bbed346d.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/c1cb3fb3b77e/vmlinux-bbed346d.xz
> mounted in repro: https://storage.googleapis.com/syzbot-assets/3bd548b7efd3/mount_0.gz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: [email protected]
>
> ------------[ cut here ]------------
> DEBUG_LOCKS_WARN_ON(1)
> WARNING: CPU: 1 PID: 3031 at kernel/locking/lockdep.c:231 check_wait_context kernel/locking/lockdep.c:4727 [inline]
> WARNING: CPU: 1 PID: 3031 at kernel/locking/lockdep.c:231 __lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
> Modules linked in:
> CPU: 1 PID: 3031 Comm: syz-executor196 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
> pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : check_wait_context kernel/locking/lockdep.c:4727 [inline]
> pc : __lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
> lr : hlock_class kernel/locking/lockdep.c:231 [inline]
> lr : check_wait_context kernel/locking/lockdep.c:4727 [inline]
> lr : __lock_acquire+0x298/0x30a4 kernel/locking/lockdep.c:5003
> sp : ffff8000129f3900
> x29: ffff8000129f39e0 x28: 0000000000000001 x27: ffff0000c5371aa8
> x26: ffff80000cb49def x25: ffff0000c53724d8 x24: 0000000000000000
> x23: 0000000000000000 x22: 0000000000000001 x21: 0000000000000000
> x20: 0000000000000000 x19: 55f07fe0846faa84 x18: 00000000000003e8
> x17: ffff80000bffd6bc x16: ffff80000db49158 x15: ffff0000c5371a80
> x14: 0000000000000000 x13: 0000000000000012 x12: ffff80000d5ef920
> x11: ff808000081c0d5c x10: ffff80000dd0b198 x9 : 62dca878cb47c300
> x8 : 0000000000000000 x7 : 4e5241575f534b43 x6 : ffff80000819545c
> x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
> x2 : 0000000000000000 x1 : 0000000100000001 x0 : 0000000000000016
> Call trace:
> check_wait_context kernel/locking/lockdep.c:4727 [inline]
> __lock_acquire+0x2b0/0x30a4 kernel/locking/lockdep.c:5003
> lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
> __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
> _raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
> spin_lock include/linux/spinlock.h:349 [inline]
> nilfs_palloc_clear_cache fs/nilfs2/alloc.c:848 [inline]
> nilfs_palloc_destroy_cache+0x2c/0xb8 fs/nilfs2/alloc.c:860
> nilfs_mdt_clear+0x34/0x70 fs/nilfs2/mdt.c:478
> nilfs_clear_inode+0x64/0x140 fs/nilfs2/inode.c:886
> nilfs_evict_inode+0x68/0x1cc fs/nilfs2/inode.c:908
> evict+0xec/0x334 fs/inode.c:665
> iput_final fs/inode.c:1748 [inline]
> iput+0x2c4/0x324 fs/inode.c:1774
> nilfs_put_super+0x6c/0x9c fs/nilfs2/super.c:476
> generic_shutdown_super+0x8c/0x190 fs/super.c:491
> kill_block_super+0x30/0x78 fs/super.c:1427
> deactivate_locked_super+0x70/0xe8 fs/super.c:332
> deactivate_super+0xd0/0xd4 fs/super.c:363
> cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186
> __cleanup_mnt+0x20/0x30 fs/namespace.c:1193
> task_work_run+0xc4/0x14c kernel/task_work.c:177
> resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
> do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
> prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
> exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
> el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:637
> el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
> el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
> irq event stamp: 356107
> hardirqs last enabled at (356107): [<ffff80000bfc8a34>] __raw_spin_unlock_irq include/linux/spinlock_api_smp.h:159 [inline]
> hardirqs last enabled at (356107): [<ffff80000bfc8a34>] _raw_spin_unlock_irq+0x3c/0x70 kernel/locking/spinlock.c:202
> hardirqs last disabled at (356106): [<ffff80000bfc8834>] __raw_spin_lock_irq include/linux/spinlock_api_smp.h:117 [inline]
> hardirqs last disabled at (356106): [<ffff80000bfc8834>] _raw_spin_lock_irq+0x34/0x9c kernel/locking/spinlock.c:170
> softirqs last enabled at (355348): [<ffff80000801c33c>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
> softirqs last disabled at (355346): [<ffff80000801c308>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
> ---[ end trace 0000000000000000 ]---
> Unable to handle kernel NULL pointer dereference at virtual address 00000000000000b8
> Mem abort info:
> ESR = 0x0000000096000004
> EC = 0x25: DABT (current EL), IL = 32 bits
> SET = 0, FnV = 0
> EA = 0, S1PTW = 0
> FSC = 0x04: level 0 translation fault
> Data abort info:
> ISV = 0, ISS = 0x00000004
> CM = 0, WnR = 0
> user pgtable: 4k pages, 48-bit VAs, pgdp=000000010ae77000
> [00000000000000b8] pgd=0000000000000000, p4d=0000000000000000
> Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
> Modules linked in:
> CPU: 1 PID: 3031 Comm: syz-executor196 Tainted: G W 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
> pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> pc : check_wait_context kernel/locking/lockdep.c:4727 [inline]
> pc : __lock_acquire+0x2d0/0x30a4 kernel/locking/lockdep.c:5003
> lr : hlock_class kernel/locking/lockdep.c:231 [inline]
> lr : check_wait_context kernel/locking/lockdep.c:4727 [inline]
> lr : __lock_acquire+0x298/0x30a4 kernel/locking/lockdep.c:5003
> sp : ffff8000129f3900
> x29: ffff8000129f39e0 x28: 0000000000000001 x27: ffff0000c5371aa8
> x26: ffff80000cb49def x25: ffff0000c53724d8 x24: 0000000000000000
> x23: 0000000000000000 x22: 0000000000000001 x21: 0000000000000000
> x20: 0000000000000000 x19: 55f07fe0846faa84 x18: 00000000000003e8
> x17: ffff80000bffd6bc x16: ffff80000db49158 x15: ffff0000c5371a80
> x14: 0000000000000000 x13: 0000000000000012 x12: ffff80000d5ef920
> x11: ff808000081c0d5c x10: ffff80000dd0b198 x9 : 0000000000040a84
> x8 : 0000000000000000 x7 : 4e5241575f534b43 x6 : ffff80000819545c
> x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
> x2 : 0000000000000000 x1 : 0000000100000001 x0 : 0000000000000016
> Call trace:
> hlock_class kernel/locking/lockdep.c:222 [inline]
> check_wait_context kernel/locking/lockdep.c:4728 [inline]
> __lock_acquire+0x2d0/0x30a4 kernel/locking/lockdep.c:5003
> lock_acquire+0x100/0x1f8 kernel/locking/lockdep.c:5666
> __raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
> _raw_spin_lock+0x54/0x6c kernel/locking/spinlock.c:154
> spin_lock include/linux/spinlock.h:349 [inline]
> nilfs_palloc_clear_cache fs/nilfs2/alloc.c:848 [inline]
> nilfs_palloc_destroy_cache+0x2c/0xb8 fs/nilfs2/alloc.c:860
> nilfs_mdt_clear+0x34/0x70 fs/nilfs2/mdt.c:478
> nilfs_clear_inode+0x64/0x140 fs/nilfs2/inode.c:886
> nilfs_evict_inode+0x68/0x1cc fs/nilfs2/inode.c:908
> evict+0xec/0x334 fs/inode.c:665
> iput_final fs/inode.c:1748 [inline]
> iput+0x2c4/0x324 fs/inode.c:1774
> nilfs_put_super+0x6c/0x9c fs/nilfs2/super.c:476
> generic_shutdown_super+0x8c/0x190 fs/super.c:491
> kill_block_super+0x30/0x78 fs/super.c:1427
> deactivate_locked_super+0x70/0xe8 fs/super.c:332
> deactivate_super+0xd0/0xd4 fs/super.c:363
> cleanup_mnt+0x1f8/0x234 fs/namespace.c:1186
> __cleanup_mnt+0x20/0x30 fs/namespace.c:1193
> task_work_run+0xc4/0x14c kernel/task_work.c:177
> resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
> do_notify_resume+0x174/0x1f0 arch/arm64/kernel/signal.c:1127
> prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:137 [inline]
> exit_to_user_mode arch/arm64/kernel/entry-common.c:142 [inline]
> el0_svc+0x9c/0x150 arch/arm64/kernel/entry-common.c:637
> el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
> el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
> Code: b002db8a 91056210 9106614a b9400329 (3942e114)
> ---[ end trace 0000000000000000 ]---
> ----------------
> Code disassembly (best guess):
> 0: b002db8a adrp x10, 0x5b71000
> 4: 91056210 add x16, x16, #0x158
> 8: 9106614a add x10, x10, #0x198
> c: b9400329 ldr w9, [x25]
> * 10: 3942e114 ldrb w20, [x8, #184] <-- trapping instruction
>
>
> ---
> This report 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 [email protected].
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
This is the same bug as below:
#syz dup: BUG: unable to handle kernel paging request in kernfs_put_active
The bugfix for this is the patch titled "fs: fix UAF/GPF bug in
nilfs_mdt_destroy", which is merged in the mainline after the commit
of the tested kernel.
I confirmed that the fix patch suppresses the bug by testing with the
C-reproducer.
Ryusuke Konishi