syzbot


possible deadlock in ocfs2_page_mkwrite

Status: upstream: reported on 2025/07/10 06:01
Reported-by: syzbot+b9b1ce4b60eef1b43236@syzkaller.appspotmail.com
First crash: 6d16h, last: 6d16h
Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in ocfs2_page_mkwrite ocfs2 4 C done 1182 4h41m 307d 0/29 upstream: reported C repro on 2024/09/12 09:35
linux-6.1 possible deadlock in ocfs2_page_mkwrite 4 6 170d 254d 0/3 auto-obsoleted due to no activity on 2025/05/07 01:52
linux-5.15 possible deadlock in ocfs2_page_mkwrite 4 14 27d 303d 0/3 upstream: reported on 2024/09/16 20:58
linux-6.1 possible deadlock in ocfs2_page_mkwrite (2) 4 1 23d 23d 0/3 upstream: reported on 2025/06/23 15:48

Sample crash report:
ocfs2: Mounting device (7,6) on (node local, slot 0) with writeback data mode.
======================================================
WARNING: possible circular locking dependency detected
6.6.96-syzkaller #0 Not tainted
------------------------------------------------------
syz.6.1684/13983 is trying to acquire lock:
ffff8880771edbe0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_page_mkwrite+0x2d0/0xd10 fs/ocfs2/mmap.c:142

but task is already holding lock:
ffff88804f506510 (sb_pagefaults#6){.+.+}-{0:0}, at: do_page_mkwrite+0x153/0x3e0 mm/memory.c:2950

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #2 (sb_pagefaults#6){.+.+}-{0:0}:
       percpu_down_read include/linux/percpu-rwsem.h:51 [inline]
       __sb_start_write include/linux/fs.h:1633 [inline]
       sb_start_pagefault include/linux/fs.h:1737 [inline]
       ocfs2_page_mkwrite+0x18b/0xd10 fs/ocfs2/mmap.c:122
       do_page_mkwrite+0x153/0x3e0 mm/memory.c:2950
       do_shared_fault mm/memory.c:4695 [inline]
       do_fault mm/memory.c:4757 [inline]
       do_pte_missing mm/memory.c:3688 [inline]
       handle_pte_fault mm/memory.c:5025 [inline]
       __handle_mm_fault mm/memory.c:5166 [inline]
       handle_mm_fault+0x19b8/0x4920 mm/memory.c:5331
       faultin_page mm/gup.c:868 [inline]
       __get_user_pages+0x5ea/0x1470 mm/gup.c:1167
       __get_user_pages_locked mm/gup.c:1495 [inline]
       __gup_longterm_locked+0x22bb/0x2920 mm/gup.c:2113
       internal_get_user_pages_fast+0x217f/0x2730 mm/gup.c:3213
       iov_iter_extract_user_pages lib/iov_iter.c:1785 [inline]
       iov_iter_extract_pages+0x393/0x790 lib/iov_iter.c:1848
       dio_refill_pages fs/direct-io.c:173 [inline]
       dio_get_page fs/direct-io.c:214 [inline]
       do_direct_IO fs/direct-io.c:914 [inline]
       __blockdev_direct_IO+0x10d6/0x3420 fs/direct-io.c:1248
       ocfs2_direct_IO+0x240/0x2b0 fs/ocfs2/aops.c:2468
       generic_file_read_iter+0x317/0x4f0 mm/filemap.c:2855
       ocfs2_file_read_iter+0x476/0xa30 fs/ocfs2/file.c:2588
       call_read_iter include/linux/fs.h:2012 [inline]
       new_sync_read fs/read_write.c:389 [inline]
       vfs_read+0x431/0x920 fs/read_write.c:470
       ksys_read+0x147/0x250 fs/read_write.c:613
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #1 (&mm->mmap_lock){++++}-{3:3}:
       __might_fault+0xc6/0x120 mm/memory.c:5946
       _copy_to_user+0x2a/0xa0 lib/usercopy.c:36
       copy_to_user include/linux/uaccess.h:191 [inline]
       fiemap_fill_next_extent+0x1c1/0x390 fs/ioctl.c:145
       ocfs2_fiemap+0x882/0xc80 fs/ocfs2/extent_map.c:796
       ioctl_fiemap fs/ioctl.c:220 [inline]
       do_vfs_ioctl+0x140c/0x1bb0 fs/ioctl.c:811
       __do_sys_ioctl fs/ioctl.c:869 [inline]
       __se_sys_ioctl+0x83/0x170 fs/ioctl.c:857
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

-> #0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}:
       check_prev_add kernel/locking/lockdep.c:3134 [inline]
       check_prevs_add kernel/locking/lockdep.c:3253 [inline]
       validate_chain kernel/locking/lockdep.c:3869 [inline]
       __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
       lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
       down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
       ocfs2_page_mkwrite+0x2d0/0xd10 fs/ocfs2/mmap.c:142
       do_page_mkwrite+0x153/0x3e0 mm/memory.c:2950
       do_shared_fault mm/memory.c:4695 [inline]
       do_fault mm/memory.c:4757 [inline]
       do_pte_missing mm/memory.c:3688 [inline]
       handle_pte_fault mm/memory.c:5025 [inline]
       __handle_mm_fault mm/memory.c:5166 [inline]
       handle_mm_fault+0x19b8/0x4920 mm/memory.c:5331
       faultin_page mm/gup.c:868 [inline]
       __get_user_pages+0x5ea/0x1470 mm/gup.c:1167
       __get_user_pages_locked mm/gup.c:1495 [inline]
       __gup_longterm_locked+0x22bb/0x2920 mm/gup.c:2113
       internal_get_user_pages_fast+0x217f/0x2730 mm/gup.c:3213
       iov_iter_extract_user_pages lib/iov_iter.c:1785 [inline]
       iov_iter_extract_pages+0x393/0x790 lib/iov_iter.c:1848
       dio_refill_pages fs/direct-io.c:173 [inline]
       dio_get_page fs/direct-io.c:214 [inline]
       do_direct_IO fs/direct-io.c:914 [inline]
       __blockdev_direct_IO+0x10d6/0x3420 fs/direct-io.c:1248
       ocfs2_direct_IO+0x240/0x2b0 fs/ocfs2/aops.c:2468
       generic_file_read_iter+0x317/0x4f0 mm/filemap.c:2855
       ocfs2_file_read_iter+0x476/0xa30 fs/ocfs2/file.c:2588
       call_read_iter include/linux/fs.h:2012 [inline]
       new_sync_read fs/read_write.c:389 [inline]
       vfs_read+0x431/0x920 fs/read_write.c:470
       ksys_read+0x147/0x250 fs/read_write.c:613
       do_syscall_x64 arch/x86/entry/common.c:51 [inline]
       do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
       entry_SYSCALL_64_after_hwframe+0x68/0xd2

other info that might help us debug this:

Chain exists of:
  &ocfs2_file_ip_alloc_sem_key --> &mm->mmap_lock --> sb_pagefaults#6

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  rlock(sb_pagefaults#6);
                               lock(&mm->mmap_lock);
                               lock(sb_pagefaults#6);
  lock(&ocfs2_file_ip_alloc_sem_key);

 *** DEADLOCK ***

3 locks held by syz.6.1684/13983:
 #0: ffff88807ab294c8 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2a3/0x330 fs/file.c:1042
 #1: ffff888077f81e20 (&mm->mmap_lock){++++}-{3:3}, at: mmap_read_lock_killable include/linux/mmap_lock.h:155 [inline]
 #1: ffff888077f81e20 (&mm->mmap_lock){++++}-{3:3}, at: __get_user_pages_locked mm/gup.c:1486 [inline]
 #1: ffff888077f81e20 (&mm->mmap_lock){++++}-{3:3}, at: __gup_longterm_locked+0x225d/0x2920 mm/gup.c:2113
 #2: ffff88804f506510 (sb_pagefaults#6){.+.+}-{0:0}, at: do_page_mkwrite+0x153/0x3e0 mm/memory.c:2950

stack backtrace:
CPU: 1 PID: 13983 Comm: syz.6.1684 Not tainted 6.6.96-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x16c/0x230 lib/dump_stack.c:106
 check_noncircular+0x2bd/0x3c0 kernel/locking/lockdep.c:2187
 check_prev_add kernel/locking/lockdep.c:3134 [inline]
 check_prevs_add kernel/locking/lockdep.c:3253 [inline]
 validate_chain kernel/locking/lockdep.c:3869 [inline]
 __lock_acquire+0x2ddb/0x7c80 kernel/locking/lockdep.c:5137
 lock_acquire+0x197/0x410 kernel/locking/lockdep.c:5754
 down_write+0x97/0x1f0 kernel/locking/rwsem.c:1573
 ocfs2_page_mkwrite+0x2d0/0xd10 fs/ocfs2/mmap.c:142
 do_page_mkwrite+0x153/0x3e0 mm/memory.c:2950
 do_shared_fault mm/memory.c:4695 [inline]
 do_fault mm/memory.c:4757 [inline]
 do_pte_missing mm/memory.c:3688 [inline]
 handle_pte_fault mm/memory.c:5025 [inline]
 __handle_mm_fault mm/memory.c:5166 [inline]
 handle_mm_fault+0x19b8/0x4920 mm/memory.c:5331
 faultin_page mm/gup.c:868 [inline]
 __get_user_pages+0x5ea/0x1470 mm/gup.c:1167
 __get_user_pages_locked mm/gup.c:1495 [inline]
 __gup_longterm_locked+0x22bb/0x2920 mm/gup.c:2113
 internal_get_user_pages_fast+0x217f/0x2730 mm/gup.c:3213
 iov_iter_extract_user_pages lib/iov_iter.c:1785 [inline]
 iov_iter_extract_pages+0x393/0x790 lib/iov_iter.c:1848
 dio_refill_pages fs/direct-io.c:173 [inline]
 dio_get_page fs/direct-io.c:214 [inline]
 do_direct_IO fs/direct-io.c:914 [inline]
 __blockdev_direct_IO+0x10d6/0x3420 fs/direct-io.c:1248
 ocfs2_direct_IO+0x240/0x2b0 fs/ocfs2/aops.c:2468
 generic_file_read_iter+0x317/0x4f0 mm/filemap.c:2855
 ocfs2_file_read_iter+0x476/0xa30 fs/ocfs2/file.c:2588
 call_read_iter include/linux/fs.h:2012 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x431/0x920 fs/read_write.c:470
 ksys_read+0x147/0x250 fs/read_write.c:613
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:81
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fa489f8e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fa48ad20038 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 00007fa48a1b5fa0 RCX: 00007fa489f8e929
RDX: 0000000000001000 RSI: 0000200000001400 RDI: 0000000000000004
RBP: 00007fa48a010b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007fa48a1b5fa0 R15: 00007ffdbbbe37f8
 </TASK>
(syz.6.1684,13983,0):ocfs2_dio_end_io:2428 ERROR: Direct IO failed, bytes = -4

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/10 06:01 linux-6.6.y a5df3a702b2c 956bd956 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-6-kasan possible deadlock in ocfs2_page_mkwrite
* Struck through repros no longer work on HEAD.