[syzbot] WARNING in reiserfs_lookup

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syzbot found the following issue on:

HEAD commit:    a41a877bc12d Merge branch 'for-next/fixes' 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=1180b113080000
kernel config:  https://syzkaller.appspot.com/x/.config?x=5cea15779c42821c
dashboard link: https://syzkaller.appspot.com/bug?extid=392ac209604cc18792e5
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

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

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email protected]

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(lock->magic != lock)
WARNING: CPU: 1 PID: 13919 at kernel/locking/mutex.c:582 __mutex_lock_common+0x49c/0xc28 kernel/locking/mutex.c:582
Modules linked in:
CPU: 1 PID: 13919 Comm: syz-executor.1 Not tainted 6.0.0-rc2-syzkaller-16455-ga41a877bc12d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/20/2022
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __mutex_lock_common+0x49c/0xc28 kernel/locking/mutex.c:582
lr : __mutex_lock_common+0x49c/0xc28 kernel/locking/mutex.c:582
sp : ffff80001404b8e0
x29: ffff80001404b950 x28: ffff80000ee9a000 x27: ffff0000e7ff7c30
x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000002
x23: ffff800008794be8 x22: 0000000000000000 x21: 0000000000000000
x20: 0000000000000000 x19: ffff000100ce2228
 x18: 0000000000000144

x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000000 x13: 0000000000000012 x12: 0000000000040000
x11: 0000000000008995 x10: ffff800017d28000 x9 : 8ae7bd2ab6f62200
x8 : 8ae7bd2ab6f62200 x7 : 4e5241575f534b43 x6 : ffff800008197c8c
x5 : 0000000000000000 x4 : 0000000000000001 x3 : 0000000000000000
x2 : 0000000000000000 x1 : 0000000100000000 x0 : 0000000000000028
Call trace:
 __mutex_lock_common+0x49c/0xc28 kernel/locking/mutex.c:582
 __mutex_lock kernel/locking/mutex.c:747 [inline]
 mutex_lock_nested+0x38/0x44 kernel/locking/mutex.c:799
 reiserfs_write_lock+0x3c/0x64 fs/reiserfs/lock.c:27
 reiserfs_lookup+0xa4/0x1c4 fs/reiserfs/namei.c:364
 lookup_open fs/namei.c:3391 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x738/0x11c4 fs/namei.c:3688
 do_filp_open+0xdc/0x1b8 fs/namei.c:3718
 do_sys_openat2+0xb8/0x22c fs/open.c:1311
 do_sys_open fs/open.c:1327 [inline]
 __do_sys_openat fs/open.c:1343 [inline]
 __se_sys_openat fs/open.c:1338 [inline]
 __arm64_sys_openat+0xb0/0xe0 fs/open.c:1338
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x154 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x18c/0x190
irq event stamp: 1381
hardirqs last  enabled at (1381): [<ffff8000085e9378>] seqcount_lockdep_reader_access include/linux/seqlock.h:104 [inline]
hardirqs last  enabled at (1381): [<ffff8000085e9378>] read_seqbegin include/linux/seqlock.h:836 [inline]
hardirqs last  enabled at (1381): [<ffff8000085e9378>] d_alloc_parallel+0x254/0xad0 fs/dcache.c:2657
hardirqs last disabled at (1380): [<ffff8000085e9300>] seqcount_lockdep_reader_access include/linux/seqlock.h:101 [inline]
hardirqs last disabled at (1380): [<ffff8000085e9300>] read_seqbegin include/linux/seqlock.h:836 [inline]
hardirqs last disabled at (1380): [<ffff8000085e9300>] d_alloc_parallel+0x1dc/0xad0 fs/dcache.c:2657
softirqs last  enabled at (1248): [<ffff80000801c1f4>] local_bh_enable+0x10/0x34 include/linux/bottom_half.h:32
softirqs last disabled at (1246): [<ffff80000801c1c0>] local_bh_disable+0x10/0x34 include/linux/bottom_half.h:19
---[ end trace 0000000000000000 ]---
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
Mem abort info:
  ESR = 0x0000000086000006
  EC = 0x21: IABT (current EL), IL = 32 bits
  SET = 0, FnV = 0
  EA = 0, S1PTW = 0
  FSC = 0x06: level 2 translation fault
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000140c5a000
[0000000000000000] pgd=080000012f58f003, p4d=080000012f58f003, pud=080000012f58c003, pmd=0000000000000000
Internal error: Oops: 86000006 [#1] PREEMPT SMP
Modules linked in:
CPU: 1 PID: 13919 Comm: syz-executor.1 Tainted: G        W          6.0.0-rc2-syzkaller-16455-ga41a877bc12d #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/20/2022
pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : 0x0
lr : get_third_component fs/reiserfs/namei.c:196 [inline]
lr : reiserfs_find_entry+0x130/0x298 fs/reiserfs/namei.c:317
sp : ffff80001404b960
x29: ffff80001404b990 x28: 0000000000000000 x27: ffff0000e7ff7c30
x26: ffff0000e7ffc000 x25: ffff0000eea4f000 x24: 0000000010000000
x23: ffff0000e7ffc070 x22: 0000000000000005 x21: ffff80001404b9e0
x20: ffff80001404ba48 x19: ffff0000eb8c0190 x18: 0000000000000144
x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
x14: 0000000000000002 x13: 0000000000000002 x12: 0000000000040000
x11: 000000000003ffff x10: ffff800017d28000 x9 : ffff80000875c888
x8 : 0000000000000000 x7 : 4e5241575f534b43 x6 : ffff800008794be8
x5 : 0000000000000000 x4 : ffff80001404b9e0 x3 : ffff80001404ba48
x2 : 0000000000000005 x1 : 0000000000000005 x0 : ffff0000e7ffc070
Call trace:
 0x0
 reiserfs_lookup+0xc4/0x1c4 fs/reiserfs/namei.c:368
 lookup_open fs/namei.c:3391 [inline]
 open_last_lookups fs/namei.c:3481 [inline]
 path_openat+0x738/0x11c4 fs/namei.c:3688
 do_filp_open+0xdc/0x1b8 fs/namei.c:3718
 do_sys_openat2+0xb8/0x22c fs/open.c:1311
 do_sys_open fs/open.c:1327 [inline]
 __do_sys_openat fs/open.c:1343 [inline]
 __se_sys_openat fs/open.c:1338 [inline]
 __arm64_sys_openat+0xb0/0xe0 fs/open.c:1338
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
 el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
 do_el0_svc+0x48/0x154 arch/arm64/kernel/syscall.c:206
 el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:624
 el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:642
 el0t_64_sync+0x18c/0x190
Code: bad PC value
---[ end trace 0000000000000000 ]---


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