====================================================== WARNING: possible circular locking dependency detected 6.13.0-rc3-syzkaller-00136-g8faabc041a00 #0 Not tainted ------------------------------------------------------ syz.2.3788/20732 is trying to acquire lock: ffff8880593921f0 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: inode_lock include/linux/fs.h:818 [inline] ffff8880593921f0 (&sb->s_type->i_mutex_key#25){++++}-{4:4}, at: __generic_file_fsync+0xb0/0x1f0 fs/libfs.c:1536 but task is already holding lock: ffff888142b8e278 (&q->q_usage_counter(io)#26){++++}-{0:0}, at: loop_set_status+0x1d9/0x700 drivers/block/loop.c:1267 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&q->q_usage_counter(io)#26){++++}-{0:0}: bio_queue_enter block/blk.h:75 [inline] blk_mq_submit_bio+0x1fb6/0x24c0 block/blk-mq.c:3090 __submit_bio+0x384/0x540 block/blk-core.c:629 __submit_bio_noacct_mq block/blk-core.c:710 [inline] submit_bio_noacct_nocheck+0x698/0xd70 block/blk-core.c:739 submit_bio_noacct+0x93a/0x1e20 block/blk-core.c:868 mpage_bio_submit_write fs/mpage.c:83 [inline] __mpage_writepage+0x12ae/0x1790 fs/mpage.c:622 write_cache_pages+0xb3/0x130 mm/page-writeback.c:2659 mpage_writepages+0xd1/0x180 fs/mpage.c:666 do_writepages+0x1b6/0x820 mm/page-writeback.c:2702 filemap_fdatawrite_wbc mm/filemap.c:397 [inline] filemap_fdatawrite_wbc+0x104/0x160 mm/filemap.c:387 __filemap_fdatawrite_range+0xb3/0xf0 mm/filemap.c:430 filemap_write_and_wait_range mm/filemap.c:684 [inline] filemap_write_and_wait_range+0xa3/0x130 mm/filemap.c:675 direct_write_fallback+0xc1/0x1a0 fs/libfs.c:2089 __generic_file_write_iter+0x1df/0x240 mm/filemap.c:4152 generic_file_write_iter+0xe1/0x340 mm/filemap.c:4182 new_sync_write fs/read_write.c:586 [inline] vfs_write+0x5b1/0x1150 fs/read_write.c:679 ksys_write+0x12b/0x250 fs/read_write.c:731 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&sb->s_type->i_mutex_key#25){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 down_write+0x93/0x200 kernel/locking/rwsem.c:1577 inode_lock include/linux/fs.h:818 [inline] __generic_file_fsync+0xb0/0x1f0 fs/libfs.c:1536 fat_file_fsync+0x70/0x210 fs/fat/file.c:191 vfs_fsync_range fs/sync.c:187 [inline] vfs_fsync+0x12d/0x1f0 fs/sync.c:201 __loop_update_dio+0x182/0x570 drivers/block/loop.c:204 loop_set_status+0x2a4/0x700 drivers/block/loop.c:1289 loop_set_status_old+0x163/0x1d0 drivers/block/loop.c:1388 lo_ioctl+0x65c/0x18b0 drivers/block/loop.c:1541 blkdev_ioctl+0x279/0x6d0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#26); lock(&sb->s_type->i_mutex_key#25); lock(&q->q_usage_counter(io)#26); lock(&sb->s_type->i_mutex_key#25); *** DEADLOCK *** 3 locks held by syz.2.3788/20732: #0: ffff888025600360 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_set_status+0x2a/0x700 drivers/block/loop.c:1251 #1: ffff888142b8e278 (&q->q_usage_counter(io)#26){++++}-{0:0}, at: loop_set_status+0x1d9/0x700 drivers/block/loop.c:1267 #2: ffff888142b8e2b0 (&q->q_usage_counter(queue)#10){+.+.}-{0:0}, at: loop_set_status+0x1d9/0x700 drivers/block/loop.c:1267 stack backtrace: CPU: 1 UID: 0 PID: 20732 Comm: syz.2.3788 Not tainted 6.13.0-rc3-syzkaller-00136-g8faabc041a00 #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/25/2024 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120 print_circular_bug+0x419/0x5d0 kernel/locking/lockdep.c:2074 check_noncircular+0x31a/0x400 kernel/locking/lockdep.c:2206 check_prev_add kernel/locking/lockdep.c:3161 [inline] check_prevs_add kernel/locking/lockdep.c:3280 [inline] validate_chain kernel/locking/lockdep.c:3904 [inline] __lock_acquire+0x249e/0x3c40 kernel/locking/lockdep.c:5226 lock_acquire.part.0+0x11b/0x380 kernel/locking/lockdep.c:5849 down_write+0x93/0x200 kernel/locking/rwsem.c:1577 inode_lock include/linux/fs.h:818 [inline] __generic_file_fsync+0xb0/0x1f0 fs/libfs.c:1536 fat_file_fsync+0x70/0x210 fs/fat/file.c:191 vfs_fsync_range fs/sync.c:187 [inline] vfs_fsync+0x12d/0x1f0 fs/sync.c:201 __loop_update_dio+0x182/0x570 drivers/block/loop.c:204 loop_set_status+0x2a4/0x700 drivers/block/loop.c:1289 loop_set_status_old+0x163/0x1d0 drivers/block/loop.c:1388 lo_ioctl+0x65c/0x18b0 drivers/block/loop.c:1541 blkdev_ioctl+0x279/0x6d0 block/ioctl.c:693 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:892 do_syscall_x64 arch/x86/entry/common.c:52 [inline] do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc0bf985d29 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:00007fc0c06d2038 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 00007fc0bfb75fa0 RCX: 00007fc0bf985d29 RDX: 0000000020000480 RSI: 0000000000004c02 RDI: 0000000000000004 RBP: 00007fc0bfa01aa8 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007fc0bfb75fa0 R15: 00007ffe42e86738