====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Tainted: G L ------------------------------------------------------ syz.9.10810/9582 is trying to acquire lock: ffff88801c295210 (&root->kernfs_iattr_rwsem){++++}-{4:4}, at: kernfs_iop_getattr+0x9e/0x450 fs/kernfs/inode.c:192 but task is already holding lock: ffff888025eb09b0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline] ffff888025eb09b0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:590 [inline] ffff888025eb09b0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: lo_ioctl+0x1a65/0x1fc0 drivers/block/loop.c:1541 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #2 (&q->q_usage_counter(io)#22){++++}-{0:0}: blk_alloc_queue+0x544/0x690 block/blk-core.c:504 blk_mq_alloc_queue block/blk-mq.c:4420 [inline] __blk_mq_alloc_disk+0x194/0x390 block/blk-mq.c:4467 loop_add+0x480/0xb40 drivers/block/loop.c:2045 loop_init+0xd7/0x160 drivers/block/loop.c:2284 do_one_initcall+0x250/0x870 init/main.c:1347 do_initcall_level+0x10a/0x1a0 init/main.c:1409 do_initcalls+0x59/0xa0 init/main.c:1425 kernel_init_freeable+0x29d/0x3e0 init/main.c:1658 kernel_init+0x1d/0x1d0 init/main.c:1548 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #1 (fs_reclaim){+.+.}-{0:0}: __fs_reclaim_acquire mm/page_alloc.c:4329 [inline] fs_reclaim_acquire+0x71/0x100 mm/page_alloc.c:4343 might_alloc include/linux/sched/mm.h:317 [inline] slab_pre_alloc_hook mm/slub.c:4565 [inline] slab_alloc_node mm/slub.c:4925 [inline] kmem_cache_alloc_noprof+0x64/0x5f0 mm/slub.c:4959 __kernfs_iattrs+0xdd/0x380 fs/kernfs/inode.c:36 kernfs_iattrs fs/kernfs/inode.c:60 [inline] __kernfs_setattr fs/kernfs/inode.c:73 [inline] kernfs_iop_setattr+0xe6/0x3f0 fs/kernfs/inode.c:127 notify_change+0xbba/0xea0 fs/attr.c:556 do_truncate+0x1c2/0x250 fs/open.c:68 handle_truncate fs/namei.c:4305 [inline] do_open fs/namei.c:4704 [inline] path_openat+0x2fed/0x3830 fs/namei.c:4863 do_file_open+0x23e/0x4a0 fs/namei.c:4892 do_sys_openat2+0x115/0x200 fs/open.c:1368 do_sys_open fs/open.c:1374 [inline] __do_sys_openat fs/open.c:1390 [inline] __se_sys_openat fs/open.c:1385 [inline] __x64_sys_openat+0x138/0x170 fs/open.c:1385 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&root->kernfs_iattr_rwsem){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 down_read+0x4a/0x330 kernel/locking/rwsem.c:1574 kernfs_iop_getattr+0x9e/0x450 fs/kernfs/inode.c:192 vfs_getattr_nosec+0x2e1/0x430 fs/stat.c:213 loop_query_min_dio_size drivers/block/loop.c:459 [inline] loop_assign_backing_file+0x27a/0x4b0 drivers/block/loop.c:512 loop_change_fd drivers/block/loop.c:592 [inline] lo_ioctl+0x1ad6/0x1fc0 drivers/block/loop.c:1541 lo_compat_ioctl+0x324/0x3f0 drivers/block/loop.c:1701 compat_blkdev_ioctl+0x5ea/0x7c0 block/ioctl.c:853 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x5ea/0x950 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x23e/0x6f0 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e other info that might help us debug this: Chain exists of: &root->kernfs_iattr_rwsem --> fs_reclaim --> &q->q_usage_counter(io)#22 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&q->q_usage_counter(io)#22); lock(fs_reclaim); lock(&q->q_usage_counter(io)#22); rlock(&root->kernfs_iattr_rwsem); *** DEADLOCK *** 3 locks held by syz.9.10810/9582: #0: ffff888022ffe430 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_global_lock_killable drivers/block/loop.c:118 [inline] #0: ffff888022ffe430 (&lo->lo_mutex){+.+.}-{4:4}, at: loop_change_fd drivers/block/loop.c:557 [inline] #0: ffff888022ffe430 (&lo->lo_mutex){+.+.}-{4:4}, at: lo_ioctl+0x14c7/0x1fc0 drivers/block/loop.c:1541 #1: ffff888025eb09b0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline] #1: ffff888025eb09b0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: loop_change_fd drivers/block/loop.c:590 [inline] #1: ffff888025eb09b0 (&q->q_usage_counter(io)#22){++++}-{0:0}, at: lo_ioctl+0x1a65/0x1fc0 drivers/block/loop.c:1541 #2: ffff888025eb09e8 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: blk_mq_freeze_queue include/linux/blk-mq.h:956 [inline] #2: ffff888025eb09e8 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: loop_change_fd drivers/block/loop.c:590 [inline] #2: ffff888025eb09e8 (&q->q_usage_counter(queue)#6){+.+.}-{0:0}, at: lo_ioctl+0x1a65/0x1fc0 drivers/block/loop.c:1541 stack backtrace: CPU: 0 UID: 0 PID: 9582 Comm: syz.9.10810 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2043 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain kernel/locking/lockdep.c:3908 [inline] __lock_acquire+0x1520/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5868 down_read+0x4a/0x330 kernel/locking/rwsem.c:1574 kernfs_iop_getattr+0x9e/0x450 fs/kernfs/inode.c:192 vfs_getattr_nosec+0x2e1/0x430 fs/stat.c:213 loop_query_min_dio_size drivers/block/loop.c:459 [inline] loop_assign_backing_file+0x27a/0x4b0 drivers/block/loop.c:512 loop_change_fd drivers/block/loop.c:592 [inline] lo_ioctl+0x1ad6/0x1fc0 drivers/block/loop.c:1541 lo_compat_ioctl+0x324/0x3f0 drivers/block/loop.c:1701 compat_blkdev_ioctl+0x5ea/0x7c0 block/ioctl.c:853 __do_compat_sys_ioctl fs/ioctl.c:695 [inline] __se_compat_sys_ioctl fs/ioctl.c:638 [inline] __ia32_compat_sys_ioctl+0x5ea/0x950 fs/ioctl.c:638 do_syscall_32_irqs_on arch/x86/entry/syscall_32.c:83 [inline] __do_fast_syscall_32+0x23e/0x6f0 arch/x86/entry/syscall_32.c:307 do_fast_syscall_32+0x33/0x70 arch/x86/entry/syscall_32.c:332 entry_SYSENTER_compat_after_hwframe+0x84/0x8e RIP: 0023:0xf7f430ec Code: 90 85 d2 74 0a 89 ce 81 e6 ff 0f 00 00 89 32 85 c0 74 05 c1 e9 0c 89 08 31 c0 5e 5d c3 90 0f 1f 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 58 b8 RSP: 002b:00000000f53e550c EFLAGS: 00000206 ORIG_RAX: 0000000000000036 RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000004c06 RDX: 0000000000000004 RSI: 0000000000000000 RDI: 0000000000000000 RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 ldm_validate_partition_table(): Disk read failed. Dev loop5: unable to read RDB block 0 loop5: unable to read partition table loop5: partition table beyond EOD, truncated loop_reread_partitions: partition scan of loop5 (Wk݊5) failed (rc=-5) ---------------- Code disassembly (best guess): 0: 90 nop 1: 85 d2 test %edx,%edx 3: 74 0a je 0xf 5: 89 ce mov %ecx,%esi 7: 81 e6 ff 0f 00 00 and $0xfff,%esi d: 89 32 mov %esi,(%rdx) f: 85 c0 test %eax,%eax 11: 74 05 je 0x18 13: c1 e9 0c shr $0xc,%ecx 16: 89 08 mov %ecx,(%rax) 18: 31 c0 xor %eax,%eax 1a: 5e pop %rsi 1b: 5d pop %rbp 1c: c3 ret 1d: 90 nop 1e: 0f 1f 00 nopl (%rax) 21: 51 push %rcx 22: 52 push %rdx 23: 55 push %rbp 24: 89 e5 mov %esp,%ebp 26: 0f 34 sysenter 28: cd 80 int $0x80 * 2a: 5d pop %rbp <-- trapping instruction 2b: 5a pop %rdx 2c: 59 pop %rcx 2d: c3 ret 2e: 90 nop 2f: 90 nop 30: 90 nop 31: 90 nop 32: 90 nop 33: 90 nop 34: 90 nop 35: 90 nop 36: 90 nop 37: 90 nop 38: 90 nop 39: 90 nop 3a: 90 nop 3b: 90 nop 3c: 90 nop 3d: 90 nop 3e: 58 pop %rax 3f: b8 .byte 0xb8