[syzbot] possible deadlock in page_cache_ra_unbounded

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 6feb57c2fd7c Merge tag 'kbuild-v6.2' of git://git.kernel.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13abf993880000
kernel config: https://syzkaller.appspot.com/x/.config?x=d3fb546de56fbf8d
dashboard link: https://syzkaller.appspot.com/bug?extid=47c7e14e1bd09234d0ad
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/81556e491789/disk-6feb57c2.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/065c943ec9de/vmlinux-6feb57c2.xz
kernel image: https://storage.googleapis.com/syzbot-assets/66e98c522c1f/bzImage-6feb57c2.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+47c7e1...@syzkaller.appspotmail.com

REISERFS (device loop4): Created .reiserfs_priv - reserved for xattr storage.
======================================================
WARNING: possible circular locking dependency detected
6.1.0-syzkaller-13822-g6feb57c2fd7c #0 Not tainted
------------------------------------------------------
syz-executor.4/3542 is trying to acquire lock:
ffff88803bf4f520 (mapping.invalidate_lock#11){.+.+}-{3:3}, at: filemap_invalidate_lock_shared include/linux/fs.h:811 [inline]
ffff88803bf4f520 (mapping.invalidate_lock#11){.+.+}-{3:3}, at: page_cache_ra_unbounded+0xe9/0x820 mm/readahead.c:226

but task is already holding lock:
ffff88802540e090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (&sbi->lock){+.+.}-{3:3}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__mutex_lock_common+0x1bd/0x26e0 kernel/locking/mutex.c:603
__mutex_lock kernel/locking/mutex.c:747 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:799
reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27
reiserfs_get_block+0x24e/0x5180 fs/reiserfs/inode.c:680
do_mpage_readpage+0x970/0x1c50 fs/mpage.c:208
mpage_readahead+0x210/0x380 fs/mpage.c:361
read_pages+0x169/0x9c0 mm/readahead.c:161
page_cache_ra_unbounded+0x703/0x820 mm/readahead.c:270
page_cache_sync_readahead include/linux/pagemap.h:1210 [inline]
filemap_get_pages+0x465/0x10d0 mm/filemap.c:2600
filemap_read+0x3cf/0xea0 mm/filemap.c:2694
call_read_iter include/linux/fs.h:2180 [inline]
generic_file_splice_read+0x1ff/0x5d0 fs/splice.c:309
do_splice_to fs/splice.c:793 [inline]
splice_direct_to_actor+0x41b/0xc00 fs/splice.c:865
do_splice_direct+0x279/0x3d0 fs/splice.c:974
do_sendfile+0x5fb/0xf80 fs/read_write.c:1255
__do_sys_sendfile64 fs/read_write.c:1323 [inline]
__se_sys_sendfile64+0x14f/0x1b0 fs/read_write.c:1309
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (mapping.invalidate_lock#11){.+.+}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
down_read+0x39/0x50 kernel/locking/rwsem.c:1509
filemap_invalidate_lock_shared include/linux/fs.h:811 [inline]
page_cache_ra_unbounded+0xe9/0x820 mm/readahead.c:226
do_sync_mmap_readahead+0x4b2/0x9a0
filemap_fault+0x38d/0x1060 mm/filemap.c:3154
__do_fault+0x136/0x4f0 mm/memory.c:4163
do_shared_fault mm/memory.c:4569 [inline]
do_fault mm/memory.c:4647 [inline]
handle_pte_fault mm/memory.c:4931 [inline]
__handle_mm_fault mm/memory.c:5073 [inline]
handle_mm_fault+0x18bc/0x26b0 mm/memory.c:5219
do_user_addr_fault+0x69b/0xcb0 arch/x86/mm/fault.c:1428
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x7a/0x110 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570
__put_user_4+0x12/0x20 arch/x86/lib/putuser.S:93
reiserfs_ioctl+0x14b/0x340 fs/reiserfs/ioctl.c:96
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(&sbi->lock);
lock(mapping.invalidate_lock#11);
lock(&sbi->lock);
lock(mapping.invalidate_lock#11);

*** DEADLOCK ***

1 lock held by syz-executor.4/3542:
#0: ffff88802540e090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27

stack backtrace:
CPU: 1 PID: 3542 Comm: syz-executor.4 Not tainted 6.1.0-syzkaller-13822-g6feb57c2fd7c #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1b1/0x290 lib/dump_stack.c:106
check_noncircular+0x2cc/0x390 kernel/locking/lockdep.c:2177
check_prev_add kernel/locking/lockdep.c:3097 [inline]
check_prevs_add kernel/locking/lockdep.c:3216 [inline]
validate_chain+0x1898/0x6ae0 kernel/locking/lockdep.c:3831
__lock_acquire+0x1292/0x1f60 kernel/locking/lockdep.c:5055
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
down_read+0x39/0x50 kernel/locking/rwsem.c:1509
filemap_invalidate_lock_shared include/linux/fs.h:811 [inline]
page_cache_ra_unbounded+0xe9/0x820 mm/readahead.c:226
do_sync_mmap_readahead+0x4b2/0x9a0
filemap_fault+0x38d/0x1060 mm/filemap.c:3154
__do_fault+0x136/0x4f0 mm/memory.c:4163
do_shared_fault mm/memory.c:4569 [inline]
do_fault mm/memory.c:4647 [inline]
handle_pte_fault mm/memory.c:4931 [inline]
__handle_mm_fault mm/memory.c:5073 [inline]
handle_mm_fault+0x18bc/0x26b0 mm/memory.c:5219
do_user_addr_fault+0x69b/0xcb0 arch/x86/mm/fault.c:1428
handle_page_fault arch/x86/mm/fault.c:1519 [inline]
exc_page_fault+0x7a/0x110 arch/x86/mm/fault.c:1575
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:__put_user_4+0x12/0x20 arch/x86/lib/putuser.S:95
Code: 01 31 c9 0f 01 ca c3 90 0f 01 cb 66 89 01 31 c9 0f 01 ca c3 0f 1f 40 00 48 bb fd ef ff ff ff 7f 00 00 48 39 d9 73 54 0f 01 cb <89> 01 31 c9 0f 01 ca c3 66 0f 1f 44 00 00 0f 01 cb 89 01 31 c9 0f
RSP: 0018:ffffc90014c97eb0 EFLAGS: 00050297
RAX: 0000000000000000 RBX: 00007fffffffeffd RCX: 0000000020000000
RDX: 0000000000000001 RSI: ffffffff8aedcc60 RDI: ffffffff8b4bc060
RBP: 1ffff110077e9e4b R08: dffffc0000000000 R09: fffffbfff1d2ccfe
R10: fffffbfff1d2ccfe R11: 1ffffffff1d2ccfd R12: 0000000020000000
R13: ffff88803bf4f698 R14: ffff88803bf4f258 R15: ffff8880205c9400
reiserfs_ioctl+0x14b/0x340 fs/reiserfs/ioctl.c:96
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]
__se_sys_ioctl+0xfb/0x170 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3d/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f0a0548c0d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 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 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f0a061d5168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f0a055abf80 RCX: 00007f0a0548c0d9
RDX: 0000000020000000 RSI: 0000000080087601 RDI: 0000000000000004
RBP: 00007f0a054e7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffc8aa2e79f R14: 00007f0a061d5300 R15: 0000000000022000
</TASK>
----------------
Code disassembly (best guess):
0: 01 31 add %esi,(%rcx)
2: c9 leaveq
3: 0f 01 ca clac
6: c3 retq
7: 90 nop
8: 0f 01 cb stac
b: 66 89 01 mov %ax,(%rcx)
e: 31 c9 xor %ecx,%ecx
10: 0f 01 ca clac
13: c3 retq
14: 0f 1f 40 00 nopl 0x0(%rax)
18: 48 bb fd ef ff ff ff movabs $0x7fffffffeffd,%rbx
1f: 7f 00 00
22: 48 39 d9 cmp %rbx,%rcx
25: 73 54 jae 0x7b
27: 0f 01 cb stac
* 2a: 89 01 mov %eax,(%rcx) <-- trapping instruction
2c: 31 c9 xor %ecx,%ecx
2e: 0f 01 ca clac
31: c3 retq
32: 66 0f 1f 44 00 00 nopw 0x0(%rax,%rax,1)
38: 0f 01 cb stac
3b: 89 01 mov %eax,(%rcx)
3d: 31 c9 xor %ecx,%ecx
3f: 0f .byte 0xf


---
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 syzk...@googlegroups.com.

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

[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: c0a572d9d32f Merge tag 'v6.5/vfs.mount' of git://git.kerne..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11d54c0b280000
kernel config: https://syzkaller.appspot.com/x/.config?x=f4df35260418daa6
dashboard link: https://syzkaller.appspot.com/bug?extid=47c7e14e1bd09234d0ad
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=11c01f00a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=145add7b280000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1855f91c7ed0/disk-c0a572d9.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/fbbea26cfe51/vmlinux-c0a572d9.xz
kernel image: https://storage.googleapis.com/syzbot-assets/5c9ca7f2d7aa/bzImage-c0a572d9.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/d0602a911ff3/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+47c7e1...@syzkaller.appspotmail.com

REISERFS (device loop0): Using r5 hash to sort names
REISERFS (device loop0): using 3.5.x disk format
REISERFS (device loop0): Created .reiserfs_priv - reserved for xattr storage.

======================================================
WARNING: possible circular locking dependency detected

6.4.0-syzkaller-00082-gc0a572d9d32f #0 Not tainted
------------------------------------------------------
syz-executor281/5085 is trying to acquire lock:
ffff88807d74e090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock_nested+0x69/0xe0 fs/reiserfs/lock.c:78

but task is already holding lock:

ffff888070c6e7e0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: filemap_invalidate_lock_shared include/linux/fs.h:833 [inline]
ffff888070c6e7e0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: page_cache_ra_unbounded+0x153/0x5e0 mm/readahead.c:226

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #1 (mapping.invalidate_lock#3){.+.+}-{3:3}:
down_read+0x9c/0x480 kernel/locking/rwsem.c:1520
filemap_invalidate_lock_shared include/linux/fs.h:833 [inline]
page_cache_ra_unbounded+0x153/0x5e0 mm/readahead.c:226
do_page_cache_ra mm/readahead.c:300 [inline]
page_cache_ra_order+0x6ec/0xa00 mm/readahead.c:560
do_sync_mmap_readahead mm/filemap.c:3193 [inline]
filemap_fault+0x1572/0x24c0 mm/filemap.c:3285
__do_fault+0x107/0x600 mm/memory.c:4176
do_shared_fault mm/memory.c:4585 [inline]
do_fault mm/memory.c:4663 [inline]
do_pte_missing mm/memory.c:3647 [inline]
handle_pte_fault mm/memory.c:4947 [inline]
__handle_mm_fault+0x24c9/0x41c0 mm/memory.c:5089
handle_mm_fault+0x2a7/0x9e0 mm/memory.c:5243
do_user_addr_fault+0x51a/0x1210 arch/x86/mm/fault.c:1440
handle_page_fault arch/x86/mm/fault.c:1534 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
__put_user_4+0x11/0x20 arch/x86/lib/putuser.S:89
reiserfs_ioctl+0x20d/0x330 fs/reiserfs/ioctl.c:96

vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]

__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

-> #0 (&sbi->lock){+.+.}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3113 [inline]
check_prevs_add kernel/locking/lockdep.c:3232 [inline]
validate_chain kernel/locking/lockdep.c:3847 [inline]
__lock_acquire+0x2fcd/0x5f30 kernel/locking/lockdep.c:5088
lock_acquire kernel/locking/lockdep.c:5705 [inline]
lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5670
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
reiserfs_write_lock_nested+0x69/0xe0 fs/reiserfs/lock.c:78
reiserfs_cond_resched fs/reiserfs/reiserfs.h:849 [inline]
reiserfs_cond_resched fs/reiserfs/reiserfs.h:842 [inline]
search_by_key+0x2452/0x3b60 fs/reiserfs/stree.c:712
search_for_position_by_key+0xcf/0x1180 fs/reiserfs/stree.c:874
_get_block_create_0+0x23f/0x1a70 fs/reiserfs/inode.c:305
reiserfs_get_block+0x244f/0x4100 fs/reiserfs/inode.c:695
do_mpage_readpage+0x768/0x1960 fs/mpage.c:234
mpage_readahead+0x344/0x580 fs/mpage.c:382
read_pages+0x1a2/0xd40 mm/readahead.c:161
page_cache_ra_unbounded+0x477/0x5e0 mm/readahead.c:270
do_page_cache_ra mm/readahead.c:300 [inline]
page_cache_ra_order+0x6ec/0xa00 mm/readahead.c:560
do_sync_mmap_readahead mm/filemap.c:3193 [inline]
filemap_fault+0x1572/0x24c0 mm/filemap.c:3285
__do_fault+0x107/0x600 mm/memory.c:4176
do_shared_fault mm/memory.c:4585 [inline]
do_fault mm/memory.c:4663 [inline]
do_pte_missing mm/memory.c:3647 [inline]
handle_pte_fault mm/memory.c:4947 [inline]
__handle_mm_fault+0x24c9/0x41c0 mm/memory.c:5089
handle_mm_fault+0x2a7/0x9e0 mm/memory.c:5243
do_user_addr_fault+0x51a/0x1210 arch/x86/mm/fault.c:1440
handle_page_fault arch/x86/mm/fault.c:1534 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
__put_user_4+0x11/0x20 arch/x86/lib/putuser.S:89
reiserfs_ioctl+0x20d/0x330 fs/reiserfs/ioctl.c:96

vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]

__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80

entry_SYSCALL_64_after_hwframe+0x63/0xcd

other info that might help us debug this:

Possible unsafe locking scenario:

CPU0 CPU1
---- ----

rlock(mapping.invalidate_lock#3);
lock(&sbi->lock);
lock(mapping.invalidate_lock#3);
lock(&sbi->lock);

*** DEADLOCK ***

1 lock held by syz-executor281/5085:
#0: ffff888070c6e7e0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: filemap_invalidate_lock_shared include/linux/fs.h:833 [inline]
#0: ffff888070c6e7e0 (mapping.invalidate_lock#3){.+.+}-{3:3}, at: page_cache_ra_unbounded+0x153/0x5e0 mm/readahead.c:226

stack backtrace:
CPU: 1 PID: 5085 Comm: syz-executor281 Not tainted 6.4.0-syzkaller-00082-gc0a572d9d32f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/27/2023

Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]

dump_stack_lvl+0xd9/0x150 lib/dump_stack.c:106
check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2188
check_prev_add kernel/locking/lockdep.c:3113 [inline]
check_prevs_add kernel/locking/lockdep.c:3232 [inline]
validate_chain kernel/locking/lockdep.c:3847 [inline]
__lock_acquire+0x2fcd/0x5f30 kernel/locking/lockdep.c:5088
lock_acquire kernel/locking/lockdep.c:5705 [inline]
lock_acquire+0x1b1/0x520 kernel/locking/lockdep.c:5670
__mutex_lock_common kernel/locking/mutex.c:603 [inline]
__mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747
reiserfs_write_lock_nested+0x69/0xe0 fs/reiserfs/lock.c:78
reiserfs_cond_resched fs/reiserfs/reiserfs.h:849 [inline]
reiserfs_cond_resched fs/reiserfs/reiserfs.h:842 [inline]
search_by_key+0x2452/0x3b60 fs/reiserfs/stree.c:712
search_for_position_by_key+0xcf/0x1180 fs/reiserfs/stree.c:874
_get_block_create_0+0x23f/0x1a70 fs/reiserfs/inode.c:305
reiserfs_get_block+0x244f/0x4100 fs/reiserfs/inode.c:695
do_mpage_readpage+0x768/0x1960 fs/mpage.c:234
mpage_readahead+0x344/0x580 fs/mpage.c:382
read_pages+0x1a2/0xd40 mm/readahead.c:161
page_cache_ra_unbounded+0x477/0x5e0 mm/readahead.c:270
do_page_cache_ra mm/readahead.c:300 [inline]
page_cache_ra_order+0x6ec/0xa00 mm/readahead.c:560
do_sync_mmap_readahead mm/filemap.c:3193 [inline]
filemap_fault+0x1572/0x24c0 mm/filemap.c:3285
__do_fault+0x107/0x600 mm/memory.c:4176
do_shared_fault mm/memory.c:4585 [inline]
do_fault mm/memory.c:4663 [inline]
do_pte_missing mm/memory.c:3647 [inline]
handle_pte_fault mm/memory.c:4947 [inline]
__handle_mm_fault+0x24c9/0x41c0 mm/memory.c:5089
handle_mm_fault+0x2a7/0x9e0 mm/memory.c:5243
do_user_addr_fault+0x51a/0x1210 arch/x86/mm/fault.c:1440
handle_page_fault arch/x86/mm/fault.c:1534 [inline]
exc_page_fault+0x98/0x170 arch/x86/mm/fault.c:1590
asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:570
RIP: 0010:__put_user_4+0x11/0x20 arch/x86/lib/putuser.S:91
Code: fa 0f 01 cb 66 89 01 31 c9 0f 01 ca c3 66 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 cb 48 c1 fb 3f 48 09 d9 0f 01 cb <89> 01 31 c9 0f 01 ca c3 0f 1f 80 00 00 00 00 f3 0f 1e fa f3 0f 1e
RSP: 0018:ffffc90004217ec0 EFLAGS: 00050206
RAX: 0000000000000002 RBX: 0000000000000000 RCX: 0000000020000000
RDX: 1ffff1100e18dd2b RSI: ffffffff82245cf8 RDI: ffff888070c6e958
RBP: ffffc90004217ef8 R08: 0000000000000001 R09: ffffffff8e7a9657
R10: fffffbfff1cf52ca R11: 0000000000000001 R12: ffff888070c6e4f0
R13: 0000000020000000 R14: ffff888070c6e518 R15: ffff88807bc6ec80
reiserfs_ioctl+0x20d/0x330 fs/reiserfs/ioctl.c:96

vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:870 [inline]

__se_sys_ioctl fs/ioctl.c:856 [inline]
__x64_sys_ioctl+0x19d/0x210 fs/ioctl.c:856
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f934c6b1649
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 01 18 00 00 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 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe3f7edce8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000cee5 RCX: 00007f934c6b1649
RDX: 0000000020000000 RSI: 0000000080087601 RDI: 0000000000000005
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffe3f7edd1c
R13: 00007ffe3f7edd50 R14: 00007ffe3f7edd30 R15: 000000000000002a

</TASK>
----------------
Code disassembly (best guess):

0: fa cli
1: 0f 01 cb stac
4: 66 89 01 mov %ax,(%rcx)
7: 31 c9 xor %ecx,%ecx
9: 0f 01 ca clac
c: c3 retq
d: 66 66 2e 0f 1f 84 00 data16 nopw %cs:0x0(%rax,%rax,1)
14: 00 00 00 00
18: 90 nop
19: f3 0f 1e fa endbr64
1d: 48 89 cb mov %rcx,%rbx
20: 48 c1 fb 3f sar $0x3f,%rbx
24: 48 09 d9 or %rbx,%rcx

27: 0f 01 cb stac
* 2a: 89 01 mov %eax,(%rcx) <-- trapping instruction
2c: 31 c9 xor %ecx,%ecx
2e: 0f 01 ca clac
31: c3 retq

32: 0f 1f 80 00 00 00 00 nopl 0x0(%rax)
39: f3 0f 1e fa endbr64
3d: f3 repz
3e: 0f .byte 0xf
3f: 1e (bad)


---
If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
If you attach or paste a git patch, syzbot will apply it before testing.