[syzbot] possible deadlock in do_page_mkwrite

syzbot
2022-12-12T07:03:17Z

Hello,

syzbot found the following issue on:

HEAD commit: 296a7b7eb792 Merge tag 'for-linus' of git://git.armlinux.o..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17a4643f880000
kernel config: https://syzkaller.appspot.com/x/.config?x=d58e7fe7f9cf5e24
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

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e884bd14818f/disk-296a7b7e.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/9d1ad945db61/vmlinux-296a7b7e.xz
kernel image: https://storage.googleapis.com/syzbot-assets/1295336774a6/bzImage-296a7b7e.xz

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-rc8-syzkaller-00154-g296a7b7eb792 #0 Not tainted
------------------------------------------------------
syz-executor.4/7705 is trying to acquire lock:
ffff88807ba26090 (&sbi->lock){+.+.}-{3:3}, at: reiserfs_write_lock+0x77/0xd0 fs/reiserfs/lock.c:27

but task is already holding lock:
ffff88807b57c558 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2977

which lock already depends on the new lock.

the existing dependency chain (in reverse order) is:

-> #2 (sb_pagefaults#3){.+.+}-{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:1826 [inline]
sb_start_pagefault include/linux/fs.h:1930 [inline]
filemap_page_mkwrite+0x15c/0x7a0 mm/filemap.c:3420
do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2977
do_shared_fault mm/memory.c:4618 [inline]
do_fault mm/memory.c:4686 [inline]
handle_pte_fault mm/memory.c:4954 [inline]
__handle_mm_fault mm/memory.c:5096 [inline]
handle_mm_fault+0x1c63/0x3630 mm/memory.c:5217
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#2){++++}-{3:3}:
lock_acquire+0x182/0x3c0 kernel/locking/lockdep.c:5668
__might_fault+0xb2/0x110 mm/memory.c:5645
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:2408
generic_update_time fs/inode.c:1859 [inline]
inode_update_time fs/inode.c:1872 [inline]
__file_update_time fs/inode.c:2088 [inline]
file_update_time+0x551/0x5d0 fs/inode.c:2119
filemap_page_mkwrite+0x248/0x7a0 mm/filemap.c:3421
do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2977
wp_page_shared+0x15e/0x380 mm/memory.c:3323
handle_pte_fault mm/memory.c:4972 [inline]
__handle_mm_fault mm/memory.c:5096 [inline]
handle_mm_fault+0x1e72/0x3630 mm/memory.c:5217
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#2 --> sb_pagefaults#3

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sb_pagefaults#3);
lock(&mm->mmap_lock#2);
lock(sb_pagefaults#3);
lock(&sbi->lock);

*** DEADLOCK ***

2 locks held by syz-executor.4/7705:
#0: ffff888017d7f558 (&mm->mmap_lock#2){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff888017d7f558 (&mm->mmap_lock#2){++++}-{3:3}, at: do_user_addr_fault+0x2e2/0xcb0 arch/x86/mm/fault.c:1369
#1: ffff88807b57c558 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2977

stack backtrace:
CPU: 0 PID: 7705 Comm: syz-executor.4 Not tainted 6.1.0-rc8-syzkaller-00154-g296a7b7eb792 #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+0x1b1/0x28e 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:2408
generic_update_time fs/inode.c:1859 [inline]
inode_update_time fs/inode.c:1872 [inline]
__file_update_time fs/inode.c:2088 [inline]
file_update_time+0x551/0x5d0 fs/inode.c:2119
filemap_page_mkwrite+0x248/0x7a0 mm/filemap.c:3421
do_page_mkwrite+0x19e/0x5e0 mm/memory.c:2977
wp_page_shared+0x15e/0x380 mm/memory.c:3323
handle_pte_fault mm/memory.c:4972 [inline]
__handle_mm_fault mm/memory.c:5096 [inline]
handle_mm_fault+0x1e72/0x3630 mm/memory.c:5217
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: 0033:0x7f2f83486b3f
Code: d0 eb 0b 0f 1f 84 00 00 00 00 00 48 89 f8 48 83 fa 10 0f 82 da 00 00 00 48 83 fa 20 0f 87 1f 01 00 00 0f 10 06 0f 10 4c 16 f0 <0f> 11 07 0f 11 4c 17 f0 c3 0f 1f 84 00 00 00 00 00 48 39 d1 0f 82
RSP: 002b:00007ffd6e289b38 EFLAGS: 00010287
RAX: 0000000020000080 RBX: 0000000000000000 RCX: 00007f2f83000000
RDX: 0000000000000013 RSI: 00007f2f83001548 RDI: 0000000020000080
RBP: 00007ffd6e289bf8 R08: 00007f2f83400000 R09: 00007f2f83000000
R10: 00007f2f83001530 R11: 0000000000000246 R12: 000000000004b63d
R13: 00007ffd6e289c20 R14: 00007f2f835abf80 R15: 0000000000000032
</TASK>

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