[v5.15] possible deadlock in ocfs2_page_mkwrite

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syzbot

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Sep 16, 2024, 4:58:29 PM9/16/24
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Hello,

syzbot found the following issue on:

HEAD commit: 3a5928702e71 Linux 5.15.167
git tree: linux-5.15.y
console output: https://syzkaller.appspot.com/x/log.txt?x=17ec1797980000
kernel config: https://syzkaller.appspot.com/x/.config?x=4d3fd5cca89ae935
dashboard link: https://syzkaller.appspot.com/bug?extid=5dbd91eea2d01f1bc318
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/ef5025f3d708/disk-3a592870.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/776fbdad3aa8/vmlinux-3a592870.xz
kernel image: https://storage.googleapis.com/syzbot-assets/79541db5bd16/bzImage-3a592870.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5dbd91...@syzkaller.appspotmail.com

======================================================
WARNING: possible circular locking dependency detected
5.15.167-syzkaller #0 Not tainted
------------------------------------------------------
syz.4.460/5863 is trying to acquire lock:
ffff888023e094a0 (&oi->ip_alloc_sem){++++}-{3:3}, at: ocfs2_page_mkwrite+0x301/0xbd0 fs/ocfs2/mmap.c:142

but task is already holding lock:
ffff888020308558 (sb_pagefaults#5){.+.+}-{0:0}, at: do_page_mkwrite+0x1a9/0x440 mm/memory.c:2892

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #6 (sb_pagefaults#5){.+.+}-{0:0}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
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:1910 [inline]
ocfs2_page_mkwrite+0x1d9/0xbd0 fs/ocfs2/mmap.c:122
do_page_mkwrite+0x1a9/0x440 mm/memory.c:2892
wp_page_shared+0x179/0x690 mm/memory.c:3229
handle_pte_fault mm/memory.c:4638 [inline]
__handle_mm_fault mm/memory.c:4755 [inline]
handle_mm_fault+0x2a3d/0x5960 mm/memory.c:4853
do_user_addr_fault arch/x86/mm/fault.c:1357 [inline]
handle_page_fault arch/x86/mm/fault.c:1445 [inline]
exc_page_fault+0x271/0x700 arch/x86/mm/fault.c:1501
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:568

-> #5 (&mm->mmap_lock){++++}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
down_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
mmap_read_lock+0x1c/0x50 include/linux/mmap_lock.h:117
do_user_addr_fault arch/x86/mm/fault.c:1308 [inline]
handle_page_fault arch/x86/mm/fault.c:1445 [inline]
exc_page_fault+0x596/0x700 arch/x86/mm/fault.c:1501
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:568
__get_user_nocheck_1+0x6/0x10 arch/x86/lib/getuser.S:103
fault_in_readable+0x172/0x2e0 mm/gup.c:1801
fault_in_iov_iter_readable+0x14a/0x1d0 lib/iov_iter.c:460
generic_perform_write+0x1c9/0x5b0 mm/filemap.c:3775
ext4_buffered_write_iter+0x227/0x360 fs/ext4/file.c:268
ext4_file_write_iter+0x87c/0x1990
call_write_iter include/linux/fs.h:2172 [inline]
new_sync_write fs/read_write.c:507 [inline]
vfs_write+0xacd/0xe50 fs/read_write.c:594
ksys_write+0x1a2/0x2c0 fs/read_write.c:647
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #4 (&sb->s_type->i_mutex_key#9){++++}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
down_read+0x45/0x2e0 kernel/locking/rwsem.c:1498
inode_lock_shared include/linux/fs.h:799 [inline]
ext4_bmap+0x4b/0x410 fs/ext4/inode.c:3163
bmap+0xa1/0xd0 fs/inode.c:1791
jbd2_journal_bmap fs/jbd2/journal.c:981 [inline]
__jbd2_journal_erase fs/jbd2/journal.c:1796 [inline]
jbd2_journal_flush+0x7a2/0xc90 fs/jbd2/journal.c:2502
ext4_ioctl_checkpoint fs/ext4/ioctl.c:849 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1267 [inline]
ext4_ioctl+0x3249/0x5b80 fs/ext4/ioctl.c:1276
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #3 (&journal->j_checkpoint_mutex){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
mutex_lock_io_nested+0x45/0x60 kernel/locking/mutex.c:777
jbd2_journal_flush+0x290/0xc90 fs/jbd2/journal.c:2474
ext4_ioctl_checkpoint fs/ext4/ioctl.c:849 [inline]
__ext4_ioctl fs/ext4/ioctl.c:1267 [inline]
ext4_ioctl+0x3249/0x5b80 fs/ext4/ioctl.c:1276
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
__se_sys_ioctl+0xf1/0x160 fs/ioctl.c:860
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (&journal->j_barrier){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
__mutex_lock_common+0x1da/0x25a0 kernel/locking/mutex.c:596
__mutex_lock kernel/locking/mutex.c:729 [inline]
mutex_lock_nested+0x17/0x20 kernel/locking/mutex.c:743
jbd2_journal_lock_updates+0x2aa/0x370 fs/jbd2/transaction.c:905
__ocfs2_flush_truncate_log+0x2e7/0x11c0 fs/ocfs2/alloc.c:6020
ocfs2_flush_truncate_log+0x4b/0x60 fs/ocfs2/alloc.c:6067
ocfs2_sync_fs+0x121/0x380 fs/ocfs2/super.c:403
sync_filesystem+0x1bc/0x220 fs/sync.c:66
generic_shutdown_super+0x6e/0x2c0 fs/super.c:448
kill_block_super+0x7a/0xe0 fs/super.c:1425
deactivate_locked_super+0xa0/0x110 fs/super.c:335
cleanup_mnt+0x44e/0x500 fs/namespace.c:1143
task_work_run+0x129/0x1a0 kernel/task_work.c:188
tracehook_notify_resume include/linux/tracehook.h:189 [inline]
exit_to_user_mode_loop+0x106/0x130 kernel/entry/common.c:181
exit_to_user_mode_prepare+0xb1/0x140 kernel/entry/common.c:214
__syscall_exit_to_user_mode_work kernel/entry/common.c:296 [inline]
syscall_exit_to_user_mode+0x5d/0x240 kernel/entry/common.c:307
do_syscall_64+0x47/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&ocfs2_sysfile_lock_key[args->fi_sysfile_type]#6){+.+.}-{3:3}:
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
down_write+0x38/0x60 kernel/locking/rwsem.c:1551
inode_lock include/linux/fs.h:789 [inline]
ocfs2_remove_btree_range+0x733/0x18a0 fs/ocfs2/alloc.c:5735
ocfs2_commit_truncate+0xcb3/0x2530 fs/ocfs2/alloc.c:7339
ocfs2_truncate_file+0xd3d/0x14f0 fs/ocfs2/file.c:505
ocfs2_setattr+0x165e/0x1c70 fs/ocfs2/file.c:1212
notify_change+0xc6d/0xf50 fs/attr.c:505
do_truncate+0x21c/0x300 fs/open.c:65
handle_truncate fs/namei.c:3265 [inline]
do_open fs/namei.c:3612 [inline]
path_openat+0x28a3/0x2f20 fs/namei.c:3742
do_filp_open+0x21c/0x460 fs/namei.c:3769
do_sys_openat2+0x13b/0x4f0 fs/open.c:1253
do_sys_open fs/open.c:1269 [inline]
__do_sys_creat fs/open.c:1343 [inline]
__se_sys_creat fs/open.c:1337 [inline]
__x64_sys_creat+0x11f/0x160 fs/open.c:1337
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x3b/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (&oi->ip_alloc_sem){++++}-{3:3}:
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
down_write+0x38/0x60 kernel/locking/rwsem.c:1551
ocfs2_page_mkwrite+0x301/0xbd0 fs/ocfs2/mmap.c:142
do_page_mkwrite+0x1a9/0x440 mm/memory.c:2892
wp_page_shared+0x179/0x690 mm/memory.c:3229
handle_pte_fault mm/memory.c:4638 [inline]
__handle_mm_fault mm/memory.c:4755 [inline]
handle_mm_fault+0x2a3d/0x5960 mm/memory.c:4853
do_user_addr_fault arch/x86/mm/fault.c:1357 [inline]
handle_page_fault arch/x86/mm/fault.c:1445 [inline]
exc_page_fault+0x271/0x700 arch/x86/mm/fault.c:1501
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:568

other info that might help us debug this:

Chain exists of:
&oi->ip_alloc_sem --> &mm->mmap_lock --> sb_pagefaults#5

Possible unsafe locking scenario:

CPU0 CPU1
---- ----
lock(sb_pagefaults#5);
lock(&mm->mmap_lock);
lock(sb_pagefaults#5);
lock(&oi->ip_alloc_sem);

*** DEADLOCK ***

2 locks held by syz.4.460/5863:
#0: ffff88801e562b28 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_trylock include/linux/mmap_lock.h:136 [inline]
#0: ffff88801e562b28 (&mm->mmap_lock){++++}-{3:3}, at: do_user_addr_fault arch/x86/mm/fault.c:1298 [inline]
#0: ffff88801e562b28 (&mm->mmap_lock){++++}-{3:3}, at: handle_page_fault arch/x86/mm/fault.c:1445 [inline]
#0: ffff88801e562b28 (&mm->mmap_lock){++++}-{3:3}, at: exc_page_fault+0x181/0x700 arch/x86/mm/fault.c:1501
#1: ffff888020308558 (sb_pagefaults#5){.+.+}-{0:0}, at: do_page_mkwrite+0x1a9/0x440 mm/memory.c:2892

stack backtrace:
CPU: 0 PID: 5863 Comm: syz.4.460 Not tainted 5.15.167-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
check_noncircular+0x2f8/0x3b0 kernel/locking/lockdep.c:2133
check_prev_add kernel/locking/lockdep.c:3053 [inline]
check_prevs_add kernel/locking/lockdep.c:3172 [inline]
validate_chain+0x1649/0x5930 kernel/locking/lockdep.c:3788
__lock_acquire+0x1295/0x1ff0 kernel/locking/lockdep.c:5012
lock_acquire+0x1db/0x4f0 kernel/locking/lockdep.c:5623
down_write+0x38/0x60 kernel/locking/rwsem.c:1551
ocfs2_page_mkwrite+0x301/0xbd0 fs/ocfs2/mmap.c:142
do_page_mkwrite+0x1a9/0x440 mm/memory.c:2892
wp_page_shared+0x179/0x690 mm/memory.c:3229
handle_pte_fault mm/memory.c:4638 [inline]
__handle_mm_fault mm/memory.c:4755 [inline]
handle_mm_fault+0x2a3d/0x5960 mm/memory.c:4853
do_user_addr_fault arch/x86/mm/fault.c:1357 [inline]
handle_page_fault arch/x86/mm/fault.c:1445 [inline]
exc_page_fault+0x271/0x700 arch/x86/mm/fault.c:1501
asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:568
RIP: 0033:0x7fc88687096b
Code: fa 10 73 2d 83 fa 08 73 46 83 fa 04 73 16 83 fa 01 7c 10 8a 0e 74 0a 0f b7 74 16 fe 66 89 74 17 fe 88 0f c3 8b 4c 16 fc 8b 36 <89> 4c 17 fc 89 37 c3 c5 fa 6f 06 c5 fa 6f 4c 16 f0 c5 fa 7f 07 c5
RSP: 002b:00007fff734d69f8 EFLAGS: 00010202
RAX: 0000000020000140 RBX: 0000000000000004 RCX: 0000000000737562
RDX: 0000000000000006 RSI: 0000000075622f2e RDI: 0000000020000140
RBP: 00007fc886a62a80 R08: 00007fc88672b000 R09: 0000000000000001
R10: 0000000000000001 R11: 0000000000000009 R12: 000000000002b3d7
R13: 00007fff734d6b00 R14: 0000000000000032 R15: fffffffffffffffe
</TASK>


---
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syzbot

unread,
Dec 16, 2025, 11:32:21 PM (2 days ago) Dec 16
to syzkaller...@googlegroups.com
Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.
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