Re: [syzbot] [reiserfs?] possible deadlock in do_page_mkwrite

syzbot
2022-12-23T10:50:51Z

syzbot has found a reproducer for the following issue on:

HEAD commit: 8395ae05cb5a Merge tag 'scsi-misc' of git://git.kernel.org..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=14e189f8480000
kernel config: https://syzkaller.appspot.com/x/.config?x=4e2d7bfa2d6d5a76
dashboard link: https://syzkaller.appspot.com/bug?extid=ff866d16791d4984b3c7
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1282218c480000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=148aa0a8480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/801dbf77dd1d/disk-8395ae05.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/2a057f4aa500/vmlinux-8395ae05.xz
kernel image: https://storage.googleapis.com/syzbot-assets/70a630e3d523/bzImage-8395ae05.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1b64a5dd0f67/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ff866d16791d4984b3c7@syzkaller.appspotmail.com

WARNING: possible circular locking dependency detected
6.1.0-syzkaller-14446-g8395ae05cb5a #0 Not tainted
------------------------------------------------------
syz-executor409/5148 is trying to acquire lock:
ffff888017eac090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff88802081e558 (sb_pagefaults){.+.+}-{0:0}, at: do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2947

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (sb_pagefaults){.+.+}-{0:0}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
__sb_start_write include/linux/fs.h:1811 [inline]
sb_start_pagefault include/linux/fs.h:1915 [inline]
filemap_page_mkwrite+0x15c/0x7a0 mm/filemap.c:3439
do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2947
wp_page_shared+0x15e/0x380 mm/memory.c:3295
handle_pte_fault mm/memory.c:4949 [inline]
__handle_mm_fault mm/memory.c:5073 [inline]
handle_mm_fault+0x1b79/0x26b0 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

-> #1 (&mm->mmap_lock){++++}-{3:3}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__might_fault+0xb2/0x110 mm/memory.c:5647
reiserfs_ioctl+0x11c/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

-> #0 (&sbi->lock){+.+.}-{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
__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_dirty_inode+0xdf/0x230 fs/reiserfs/super.c:704
__mark_inode_dirty+0x1e7/0x600 fs/fs-writeback.c:2419
generic_update_time fs/inode.c:1859 [inline]
inode_update_time fs/inode.c:1872 [inline]
__file_update_time fs/inode.c:2057 [inline]
file_update_time+0x551/0x5d0 fs/inode.c:2088
filemap_page_mkwrite+0x248/0x7a0 mm/filemap.c:3440
do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2947
wp_page_shared+0x15e/0x380 mm/memory.c:3295
handle_pte_fault mm/memory.c:4949 [inline]
__handle_mm_fault mm/memory.c:5073 [inline]
handle_mm_fault+0x1b79/0x26b0 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

other info that might help us debug this:

Chain exists of:
&sbi->lock --> &mm->mmap_lock --> sb_pagefaults

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sb_pagefaults);
lock(&mm->mmap_lock);
lock(sb_pagefaults);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor409/5148:
#0: ffff88801d47c758 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff88801d47c758 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault+0x2e2/0xcb0 arch/x86/mm/fault.c:1369
#1: ffff88802081e558 (sb_pagefaults){.+.+}-{0:0}, at: do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2947

stack backtrace:
CPU: 0 PID: 5148 Comm: syz-executor409 Not tainted 6.1.0-syzkaller-14446-g8395ae05cb5a #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
__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_dirty_inode+0xdf/0x230 fs/reiserfs/super.c:704
__mark_inode_dirty+0x1e7/0x600 fs/fs-writeback.c:2419
generic_update_time fs/inode.c:1859 [inline]
inode_update_time fs/inode.c:1872 [inline]
__file_update_time fs/inode.c:2057 [inline]
file_update_time+0x551/0x5d0 fs/inode.c:2088
filemap_page_mkwrite+0x248/0x7a0 mm/filemap.c:3440
do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2947
wp_page_shared+0x15e/0x380 mm/memory.c:3295
handle_pte_fault mm/memory.c:4949 [inline]
__handle_mm_fault mm/memory.c:5073 [inline]
handle_mm_fault+0x1b79/0x26b0 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: 0033:0x7f61a34e95a0
Code: 00 e8 14 26 04 00 48 8b 35 bd 5b 0b 00 31 c9 31 c0 ba 01 76 08 80 bf 10 00 00 00 e8 fa 25 04 00 b8 98 00 00 20 b9 20 00 00 00 <c7> 04 25 80 00 00 20 08 00 00 00 66 c7 04 25 84 00 00 20 20 01 48
RSP: 002b:00007ffd03dae660 EFLAGS: 00010286
RAX: 0000000020000098 RBX: 000000000000f4c9 RCX: 0000000000000020
RDX: 0000000000000000 RSI: 0000000080087601 RDI: 0000000000000004
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd03dae68c
R13: 00007ffd03dae6c0 R14: 00007ffd03dae6a0 R15: 0000000000000006