syzbot


possible deadlock in __ocfs2_write_remove_suid

Status: upstream: reported on 2025/10/13 15:29
Reported-by: syzbot+baf61a8eca78f35c11be@syzkaller.appspotmail.com
First crash: 50d, last: 33d
Similar bugs (1)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream possible deadlock in __ocfs2_write_remove_suid ocfs2 4 4 252d 395d 0/29 auto-obsoleted due to no activity on 2025/07/03 04:24

Sample crash report:
ocfs2: Mounting device (7,4) on (node local, slot 0) with writeback data mode.
======================================================
WARNING: possible circular locking dependency detected
syzkaller #0 Not tainted
------------------------------------------------------
syz.4.1227/9762 is trying to acquire lock:
ffff888062d04650 (sb_internal#4){.+.+}-{0:0}, at: __ocfs2_write_remove_suid+0x1a0/0x760 fs/ocfs2/file.c:1388

but task is already holding lock:
ffff88805c0b4da0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_inode_lock_for_extent_tree+0xd6/0x190 fs/ocfs2/file.c:2213

which lock already depends on the new lock.


the existing dependency chain (in reverse order) is:

-> #3
 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       ocfs2_read_virt_blocks+0x23f/0x8a0 fs/ocfs2/extent_map.c:984
       ocfs2_read_dir_block+0xd3/0x4d0 fs/ocfs2/dir.c:508
       ocfs2_dir_foreach_blk_el fs/ocfs2/dir.c:1842 [inline]
       ocfs2_dir_foreach_blk+0x26e/0x1900 fs/ocfs2/dir.c:1928
       ocfs2_dir_foreach fs/ocfs2/dir.c:1938 [inline]
       ocfs2_empty_dir+0x1a1/0x6c0 fs/ocfs2/dir.c:2156
       ocfs2_rename+0x204e/0x3690 fs/ocfs2/namei.c:1499
       vfs_rename+0xbbf/0x10d0 fs/namei.c:4840
       do_renameat2+0xa83/0xf70 fs/namei.c:4993
       __do_sys_rename fs/namei.c:5039 [inline]
       __se_sys_rename fs/namei.c:5037 [inline]
       __x64_sys_rename+0x82/0x90 fs/namei.c:5037
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #2 (jbd2_handle){++++}-{0:0}:
       start_this_handle+0x1338/0x15a0 fs/jbd2/transaction.c:464
       jbd2__journal_start+0x2b7/0x5a0 fs/jbd2/transaction.c:521
       jbd2_journal_start+0x26/0x30 fs/jbd2/transaction.c:560
       ocfs2_start_trans+0x374/0x6c0 fs/ocfs2/journal.c:376
       ocfs2_mknod+0xe2f/0x22b0 fs/ocfs2/namei.c:361
       ocfs2_mkdir+0x192/0x410 fs/ocfs2/namei.c:657
       vfs_mkdir+0x387/0x570 fs/namei.c:4073
       do_mkdirat+0x1d7/0x5a0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #1 (&journal->j_trans_barrier){.+.+}-{3:3}:
       down_read+0x44/0x2e0 kernel/locking/rwsem.c:1498
       ocfs2_start_trans+0x368/0x6c0 fs/ocfs2/journal.c:374
       ocfs2_mknod+0xe2f/0x22b0 fs/ocfs2/namei.c:361
       ocfs2_mkdir+0x192/0x410 fs/ocfs2/namei.c:657
       vfs_mkdir+0x387/0x570 fs/namei.c:4073
       do_mkdirat+0x1d7/0x5a0 fs/namei.c:4098
       __do_sys_mkdirat fs/namei.c:4113 [inline]
       __se_sys_mkdirat fs/namei.c:4111 [inline]
       __x64_sys_mkdirat+0x85/0x90 fs/namei.c:4111
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

-> #0 (sb_internal#4){.+.+}-{0:0}:
       check_prev_add kernel/locking/lockdep.c:3053 [inline]
       check_prevs_add kernel/locking/lockdep.c:3172 [inline]
       validate_chain kernel/locking/lockdep.c:3788 [inline]
       __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
       lock_acquire+0x197/0x3f0 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_intwrite include/linux/fs.h:1928 [inline]
       ocfs2_start_trans+0x269/0x6c0 fs/ocfs2/journal.c:372
       __ocfs2_write_remove_suid+0x1a0/0x760 fs/ocfs2/file.c:1388
       ocfs2_write_remove_suid fs/ocfs2/file.c:1429 [inline]
       ocfs2_prepare_inode_for_write fs/ocfs2/file.c:2314 [inline]
       ocfs2_file_write_iter+0x963/0x1cf0 fs/ocfs2/file.c:2454
       call_write_iter include/linux/fs.h:2173 [inline]
       new_sync_write fs/read_write.c:507 [inline]
       vfs_write+0x712/0xd00 fs/read_write.c:594
       ksys_write+0x14d/0x250 fs/read_write.c:647
       do_syscall_x64 arch/x86/entry/common.c:50 [inline]
       do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
       entry_SYSCALL_64_after_hwframe+0x66/0xd0

other info that might help us debug this:

Chain exists of:
  sb_internal#4 --> jbd2_handle --> &ocfs2_file_ip_alloc_sem_key

 Possible unsafe locking scenario:

       CPU0                    CPU1
       ----                    ----
  lock(&ocfs2_file_ip_alloc_sem_key);
                               lock(jbd2_handle);
                               lock(&ocfs2_file_ip_alloc_sem_key);
  lock(sb_internal#4);

 *** DEADLOCK ***

4 locks held by syz.4.1227/9762:
 #0: ffff8880227fb9f0 (&f->f_pos_lock){+.+.}-{3:3}, at: __fdget_pos+0x2bf/0x370 fs/file.c:1056
 #1: ffff888062d04460 (sb_writers#21){.+.+}-{0:0}, at: vfs_write+0x28a/0xd00 fs/read_write.c:590
 #2: ffff88805c0b5108 (&sb->s_type->i_mutex_key#36){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline]
 #2: ffff88805c0b5108 (&sb->s_type->i_mutex_key#36){+.+.}-{3:3}, at: ocfs2_file_write_iter+0x401/0x1cf0 fs/ocfs2/file.c:2402
 #3: ffff88805c0b4da0 (&ocfs2_file_ip_alloc_sem_key){++++}-{3:3}, at: ocfs2_inode_lock_for_extent_tree+0xd6/0x190 fs/ocfs2/file.c:2213

stack backtrace:
CPU: 0 PID: 9762 Comm: syz.4.1227 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Call Trace:
 <TASK>
 dump_stack_lvl+0x168/0x230 lib/dump_stack.c:106
 check_noncircular+0x274/0x310 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 kernel/locking/lockdep.c:3788 [inline]
 __lock_acquire+0x2c33/0x7c60 kernel/locking/lockdep.c:5012
 lock_acquire+0x197/0x3f0 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_intwrite include/linux/fs.h:1928 [inline]
 ocfs2_start_trans+0x269/0x6c0 fs/ocfs2/journal.c:372
 __ocfs2_write_remove_suid+0x1a0/0x760 fs/ocfs2/file.c:1388
 ocfs2_write_remove_suid fs/ocfs2/file.c:1429 [inline]
 ocfs2_prepare_inode_for_write fs/ocfs2/file.c:2314 [inline]
 ocfs2_file_write_iter+0x963/0x1cf0 fs/ocfs2/file.c:2454
 call_write_iter include/linux/fs.h:2173 [inline]
 new_sync_write fs/read_write.c:507 [inline]
 vfs_write+0x712/0xd00 fs/read_write.c:594
 ksys_write+0x14d/0x250 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f23a9a67fc9
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:00007f23a7ccf038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f23a9cbefa0 RCX: 00007f23a9a67fc9
RDX: 0000000000000009 RSI: 0000200000000140 RDI: 0000000000000004
RBP: 00007f23a9aeaf91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f23a9cbf038 R14: 00007f23a9cbefa0 R15: 00007ffdab8d7c38
 </TASK>

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/10/30 21:08 linux-5.15.y cc5ec8769306 2c50b6a9 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __ocfs2_write_remove_suid
2025/10/13 15:28 linux-5.15.y 29e53a5b1c4f b6605ba8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan possible deadlock in __ocfs2_write_remove_suid
* Struck through repros no longer work on HEAD.