====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.8.1792/13354 is trying to acquire lock: ffff888029f02618 (sb_internal#3){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6235 but task is already holding lock: ffff888052c79760 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:415 [inline] ffff888052c79760 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x211/0x4d0 mm/util.c:578 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&mm->mmap_lock){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_write_killable+0xa7/0x230 kernel/locking/rwsem.c:1601 mmap_write_lock_killable include/linux/mmap_lock.h:415 [inline] upgrade_mmap_lock_carefully+0xba/0x1c0 mm/mmap_lock.c:310 lock_mm_and_find_vma+0x10a/0x300 mm/mmap_lock.c:363 do_user_addr_fault+0x331/0x1390 arch/x86/mm/fault.c:1359 handle_page_fault arch/x86/mm/fault.c:1476 [inline] exc_page_fault+0x76/0xf0 arch/x86/mm/fault.c:1532 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:623 filldir+0x2bc/0x6c0 fs/readdir.c:295 dir_emit include/linux/fs.h:3959 [inline] kernfs_fop_readdir+0x537/0x870 fs/kernfs/dir.c:1910 iterate_dir+0x399/0x570 fs/readdir.c:108 __do_sys_getdents fs/readdir.c:326 [inline] __se_sys_getdents+0xe4/0x250 fs/readdir.c:312 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&root->kernfs_rwsem){++++}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 down_write+0x96/0x1f0 kernel/locking/rwsem.c:1590 kernfs_add_one+0x41/0x520 fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1093 sysfs_create_dir_ns+0x123/0x280 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x59f/0xb40 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x125/0x190 lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x111/0x2b0 fs/btrfs/sysfs.c:2641 btrfs_quota_enable+0x253/0x2600 fs/btrfs/qgroup.c:1022 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3667 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 __mutex_lock_common kernel/locking/mutex.c:598 [inline] __mutex_lock+0x187/0x1350 kernel/locking/mutex.c:760 btrfs_quota_enable+0x28e/0x2600 fs/btrfs/qgroup.c:1051 btrfs_ioctl_quota_ctl+0x183/0x1c0 fs/btrfs/ioctl.c:3667 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 join_transaction+0x1a4/0xd70 fs/btrfs/transaction.c:321 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_ioctl_subvol_setflags+0x45e/0x810 fs/btrfs/ioctl.c:1419 btrfs_ioctl+0x93a/0xd00 fs/btrfs/ioctl.c:5240 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 join_transaction+0x182/0xd70 fs/btrfs/transaction.c:320 start_transaction+0x6b6/0x1620 fs/btrfs/transaction.c:705 btrfs_ioctl_subvol_setflags+0x45e/0x810 fs/btrfs/ioctl.c:1419 btrfs_ioctl+0x93a/0xd00 fs/btrfs/ioctl.c:5240 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:598 [inline] __se_sys_ioctl+0xfc/0x170 fs/ioctl.c:584 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (sb_internal#3){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3165 [inline] check_prevs_add kernel/locking/lockdep.c:3284 [inline] validate_chain+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1799 [inline] sb_start_intwrite include/linux/fs.h:1982 [inline] start_transaction+0x56e/0x1620 fs/btrfs/transaction.c:699 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6235 inode_update_time fs/inode.c:2075 [inline] touch_atime+0x2f9/0x6d0 fs/inode.c:2148 file_accessed include/linux/fs.h:2664 [inline] btrfs_file_mmap_prepare+0xd5/0x140 fs/btrfs/file.c:2050 vfs_mmap_prepare include/linux/fs.h:2295 [inline] call_mmap_prepare mm/vma.c:2585 [inline] __mmap_region mm/vma.c:2653 [inline] mmap_region+0xb41/0x20c0 mm/vma.c:2739 do_mmap+0xc45/0x10d0 mm/mmap.c:558 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:580 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 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: sb_internal#3 --> &root->kernfs_rwsem --> &mm->mmap_lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&mm->mmap_lock); lock(&root->kernfs_rwsem); lock(&mm->mmap_lock); rlock(sb_internal#3); *** DEADLOCK *** 2 locks held by syz.8.1792/13354: #0: ffff888052c79760 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:415 [inline] #0: ffff888052c79760 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x211/0x4d0 mm/util.c:578 #1: ffff888029f02428 (sb_writers#15){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2664 [inline] #1: ffff888029f02428 (sb_writers#15){.+.+}-{0:0}, at: btrfs_file_mmap_prepare+0xd5/0x140 fs/btrfs/file.c:2050 stack backtrace: CPU: 1 UID: 0 PID: 13354 Comm: syz.8.1792 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/18/2025 Call Trace: dump_stack_lvl+0x189/0x250 lib/dump_stack.c:120 print_circular_bug+0x2ee/0x310 kernel/locking/lockdep.c:2043 check_noncircular+0x134/0x160 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+0xb9b/0x2140 kernel/locking/lockdep.c:3908 __lock_acquire+0xab9/0xd20 kernel/locking/lockdep.c:5237 lock_acquire+0x120/0x360 kernel/locking/lockdep.c:5868 percpu_down_read_internal include/linux/percpu-rwsem.h:53 [inline] percpu_down_read_freezable include/linux/percpu-rwsem.h:83 [inline] __sb_start_write include/linux/fs.h:1799 [inline] sb_start_intwrite include/linux/fs.h:1982 [inline] start_transaction+0x56e/0x1620 fs/btrfs/transaction.c:699 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6235 inode_update_time fs/inode.c:2075 [inline] touch_atime+0x2f9/0x6d0 fs/inode.c:2148 file_accessed include/linux/fs.h:2664 [inline] btrfs_file_mmap_prepare+0xd5/0x140 fs/btrfs/file.c:2050 vfs_mmap_prepare include/linux/fs.h:2295 [inline] call_mmap_prepare mm/vma.c:2585 [inline] __mmap_region mm/vma.c:2653 [inline] mmap_region+0xb41/0x20c0 mm/vma.c:2739 do_mmap+0xc45/0x10d0 mm/mmap.c:558 vm_mmap_pgoff+0x2a6/0x4d0 mm/util.c:580 ksys_mmap_pgoff+0x51f/0x760 mm/mmap.c:604 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f937398eba9 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:00007f9374788038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f9373bd6180 RCX: 00007f937398eba9 RDX: 000000000000000a RSI: 0000000000b36000 RDI: 0000200000000000 RBP: 00007f9373a11e19 R08: 0000000000000006 R09: 0000000000000000 R10: 0000000000028011 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f9373bd6218 R14: 00007f9373bd6180 R15: 00007ffdde622e18