====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.9.2177/26932 is trying to acquire lock: ffff888011b91d30 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601 but task is already holding lock: ffff888019c4d238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x275/0x8d0 fs/kernfs/dir.c:1898 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x3a/0x50 kernel/locking/rwsem.c:1590 kernfs_add_one+0x41/0x5c0 fs/kernfs/dir.c:796 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1098 sysfs_create_dir_ns+0x12f/0x2a0 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x631/0xd10 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x12b/0x1a0 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x116/0x2e0 fs/btrfs/sysfs.c:2604 btrfs_quota_enable+0x282/0x2850 fs/btrfs/qgroup.c:1034 btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3540 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/rtmutex_api.c:533 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:552 btrfs_quota_enable+0x2c6/0x2850 fs/btrfs/qgroup.c:1063 btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3540 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:597 [inline] __se_sys_ioctl+0xff/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x1a4/0xc90 fs/btrfs/transaction.c:323 start_transaction+0x6b9/0x1650 fs/btrfs/transaction.c:708 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6429 file_update_time_flags+0x2d5/0x4b0 fs/inode.c:2426 btrfs_fallocate+0x75c/0x1bb0 fs/btrfs/file.c:3145 vfs_fallocate+0x672/0x7f0 fs/open.c:340 ioctl_preallocate fs/ioctl.c:289 [inline] file_ioctl+0x5cb/0x870 fs/ioctl.c:329 do_vfs_ioctl+0xc29/0x1540 fs/ioctl.c:576 __do_sys_ioctl fs/ioctl.c:595 [inline] __se_sys_ioctl+0x82/0x170 fs/ioctl.c:583 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5574 [inline] lock_release+0x199/0x3d0 kernel/locking/lockdep.c:5889 percpu_up_read include/linux/percpu-rwsem.h:112 [inline] __sb_end_write include/linux/fs/super.h:14 [inline] sb_end_intwrite+0x26/0x1c0 include/linux/fs/super.h:101 __btrfs_end_transaction+0x248/0x640 fs/btrfs/transaction.c:1085 btrfs_dirty_inode+0x14c/0x190 fs/btrfs/inode.c:6443 touch_atime+0x2f8/0x6b0 fs/inode.c:2271 file_accessed include/linux/fs.h:2263 [inline] btrfs_file_mmap_prepare+0x189/0x200 fs/btrfs/file.c:2051 vfs_mmap_prepare include/linux/fs.h:2075 [inline] call_mmap_prepare mm/vma.c:2644 [inline] __mmap_region mm/vma.c:2743 [inline] mmap_region+0xddc/0x2230 mm/vma.c:2837 do_mmap+0xc2f/0x10c0 mm/mmap.c:559 vm_mmap_pgoff+0x2cc/0x4f0 mm/util.c:581 ksys_mmap_pgoff+0x4e8/0x720 mm/mmap.c:605 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (&mm->mmap_lock){++++}-{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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 down_read_killable+0xa4/0x220 kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601 get_mmap_lock_carefully mm/mmap_lock.c:450 [inline] lock_mm_and_find_vma+0x2d7/0x340 mm/mmap_lock.c:501 do_user_addr_fault+0x330/0x1340 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 filldir64+0x2cd/0x670 fs/readdir.c:-1 dir_emit include/linux/fs.h:3566 [inline] kernfs_fop_readdir+0x57e/0x8d0 fs/kernfs/dir.c:1915 iterate_dir+0x3a5/0x580 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:412 [inline] __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: &mm->mmap_lock --> &fs_info->qgroup_ioctl_lock --> &root->kernfs_rwsem Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&root->kernfs_rwsem); lock(&fs_info->qgroup_ioctl_lock); lock(&root->kernfs_rwsem); rlock(&mm->mmap_lock); *** DEADLOCK *** 3 locks held by syz.9.2177/26932: #0: ffff88802ae5cb28 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x252/0x320 fs/file.c:1261 #1: ffff888040feb2f8 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x29e/0x580 fs/readdir.c:101 #2: ffff888019c4d238 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x275/0x8d0 fs/kernfs/dir.c:1898 stack backtrace: CPU: 1 UID: 0 PID: 26932 Comm: syz.9.2177 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026 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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 kernel/locking/lockdep.c:5868 down_read_killable+0xa4/0x220 kernel/locking/rwsem.c:1560 mmap_read_lock_killable+0x1d/0x70 include/linux/mmap_lock.h:601 get_mmap_lock_carefully mm/mmap_lock.c:450 [inline] lock_mm_and_find_vma+0x2d7/0x340 mm/mmap_lock.c:501 do_user_addr_fault+0x330/0x1340 arch/x86/mm/fault.c:1357 handle_page_fault arch/x86/mm/fault.c:1474 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1527 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618 RIP: 0010:filldir64+0x2cd/0x670 fs/readdir.c:382 Code: 4c 24 08 48 8b 44 24 58 48 89 01 48 8b 04 24 8b 54 24 14 49 bc 00 00 00 00 00 fc ff df 66 89 41 10 80 e2 0f 88 51 12 49 63 ee 44 29 13 00 4c 8d 79 13 bf 07 00 00 00 44 89 f6 e8 cd a5 86 ff RSP: 0018:ffffc900042a7c40 EFLAGS: 00050202 RAX: 0000000000000028 RBX: ffffc900042a7e38 RCX: 0000200000000fe0 RDX: 0000000000000008 RSI: 0000200000000fb8 RDI: 0000200000001008 RBP: 0000000000000012 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: ffffed100a959b71 R12: dffffc0000000000 R13: ffff888035107000 R14: 0000000000000012 R15: 0000200000001008 dir_emit include/linux/fs.h:3566 [inline] kernfs_fop_readdir+0x57e/0x8d0 fs/kernfs/dir.c:1915 iterate_dir+0x3a5/0x580 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:412 [inline] __se_sys_getdents64+0xf1/0x280 fs/readdir.c:397 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fc4af9ec799 Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007fc4adc3e028 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9 RAX: ffffffffffffffda RBX: 00007fc4afc65fa0 RCX: 00007fc4af9ec799 RDX: 0000000000001001 RSI: 0000200000000cc0 RDI: 0000000000000003 RBP: 00007fc4afa82c99 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007fc4afc66038 R14: 00007fc4afc65fa0 R15: 00007ffec3edde38 SQUASHFS error: lzo decompression failed, data probably corrupt SQUASHFS error: Failed to read block 0x0: -5 SQUASHFS error: lzo decompression failed, data probably corrupt SQUASHFS error: Failed to read block 0x0: -5 ---------------- Code disassembly (best guess): 0: 4c 24 08 rex.WR and $0x8,%al 3: 48 8b 44 24 58 mov 0x58(%rsp),%rax 8: 48 89 01 mov %rax,(%rcx) b: 48 8b 04 24 mov (%rsp),%rax f: 8b 54 24 14 mov 0x14(%rsp),%edx 13: 49 bc 00 00 00 00 00 movabs $0xdffffc0000000000,%r12 1a: fc ff df 1d: 66 89 41 10 mov %ax,0x10(%rcx) 21: 80 e2 0f and $0xf,%dl 24: 88 51 12 mov %dl,0x12(%rcx) 27: 49 63 ee movslq %r14d,%rbp * 2a: c6 44 29 13 00 movb $0x0,0x13(%rcx,%rbp,1) <-- trapping instruction 2f: 4c 8d 79 13 lea 0x13(%rcx),%r15 33: bf 07 00 00 00 mov $0x7,%edi 38: 44 89 f6 mov %r14d,%esi 3b: e8 cd a5 86 ff call 0xff86a60d