====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.506/10178 is trying to acquire lock: ffff888025bfa770 (sb_internal#4){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6443 but task is already holding lock: ffff8880372bd1b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline] ffff8880372bd1b0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1e0/0x4e0 mm/util.c:579 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #5 (&mm->mmap_lock){++++}-{4:4}: down_read_killable+0xa4/0x220 kernel/locking/rwsem.c:1593 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+0x2d6/0x340 mm/mmap_lock.c:501 do_user_addr_fault+0x341/0x1340 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+0x2bc/0x620 fs/readdir.c:-1 dir_emit include/linux/fs.h:3578 [inline] kernfs_fop_readdir+0x583/0x960 fs/kernfs/dir.c:2000 iterate_dir+0x2f1/0x4e0 fs/readdir.c:110 __do_sys_getdents64 fs/readdir.c:399 [inline] __se_sys_getdents64+0xf1/0x280 fs/readdir.c:384 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 -> #4 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x3a/0x50 kernel/locking/rwsem.c:1625 kernfs_add_one+0x41/0x5d0 fs/kernfs/dir.c:826 kernfs_create_dir_ns+0xde/0x130 fs/kernfs/dir.c:1131 sysfs_create_dir_ns+0x12f/0x2a0 fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x62c/0xce0 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+0x118/0x2f0 fs/btrfs/sysfs.c:2604 btrfs_quota_enable+0x270/0x29d0 fs/btrfs/qgroup.c:1034 btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3541 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+0x174/0x580 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:534 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:553 btrfs_quota_enable+0x2aa/0x29d0 fs/btrfs/qgroup.c:1063 btrfs_ioctl_quota_ctl+0x186/0x1c0 fs/btrfs/ioctl.c:3541 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+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x18a/0xc60 fs/btrfs/transaction.c:324 start_transaction+0x6f8/0x1800 fs/btrfs/transaction.c:719 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6443 touch_atime+0x2f8/0x6a0 fs/inode.c:2271 file_accessed include/linux/fs.h:2264 [inline] btrfs_encoded_read+0x1b6/0x1890 fs/btrfs/inode.c:9751 btrfs_ioctl_encoded_read+0x4ea/0x850 fs/btrfs/ioctl.c:4361 btrfs_ioctl+0x316/0xd10 fs/btrfs/ioctl.c:-1 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+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #1 (btrfs_trans_num_writers){++++}-{0:0}: join_transaction+0x169/0xc60 fs/btrfs/transaction.c:323 start_transaction+0x6f8/0x1800 fs/btrfs/transaction.c:719 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6443 touch_atime+0x2f8/0x6a0 fs/inode.c:2271 file_accessed include/linux/fs.h:2264 [inline] btrfs_encoded_read+0x1b6/0x1890 fs/btrfs/inode.c:9751 btrfs_ioctl_encoded_read+0x4ea/0x850 fs/btrfs/ioctl.c:4361 btrfs_ioctl+0x316/0xd10 fs/btrfs/ioctl.c:-1 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+0x174/0x580 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (sb_internal#4){.+.+}-{0:0}: 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+0x1520/0x2cc0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 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/super.h:19 [inline] sb_start_intwrite include/linux/fs/super.h:177 [inline] start_transaction+0x5b1/0x1800 fs/btrfs/transaction.c:713 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6443 touch_atime+0x2f8/0x6a0 fs/inode.c:2271 file_accessed include/linux/fs.h:2264 [inline] btrfs_file_mmap_prepare+0x189/0x200 fs/btrfs/file.c:2056 vfs_mmap_prepare include/linux/fs.h:2076 [inline] call_mmap_prepare mm/vma.c:2672 [inline] __mmap_region mm/vma.c:2755 [inline] mmap_region+0xe8b/0x2340 mm/vma.c:2857 do_mmap+0xc1e/0x10b0 mm/mmap.c:560 vm_mmap_pgoff+0x275/0x4e0 mm/util.c:581 ksys_mmap_pgoff+0x4a6/0x720 mm/mmap.c:606 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 other info that might help us debug this: Chain exists of: sb_internal#4 --> &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#4); *** DEADLOCK *** 2 locks held by syz.4.506/10178: #0: ffff8880372bd1b0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline] #0: ffff8880372bd1b0 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1e0/0x4e0 mm/util.c:579 #1: ffff888025bfa480 (sb_writers#23){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2264 [inline] #1: ffff888025bfa480 (sb_writers#23){.+.+}-{0:0}, at: btrfs_file_mmap_prepare+0x189/0x200 fs/btrfs/file.c:2056 stack backtrace: CPU: 0 UID: 0 PID: 10178 Comm: syz.4.506 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 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+0x1520/0x2cc0 kernel/locking/lockdep.c:5237 lock_acquire+0x106/0x350 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/super.h:19 [inline] sb_start_intwrite include/linux/fs/super.h:177 [inline] start_transaction+0x5b1/0x1800 fs/btrfs/transaction.c:713 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6443 touch_atime+0x2f8/0x6a0 fs/inode.c:2271 file_accessed include/linux/fs.h:2264 [inline] btrfs_file_mmap_prepare+0x189/0x200 fs/btrfs/file.c:2056 vfs_mmap_prepare include/linux/fs.h:2076 [inline] call_mmap_prepare mm/vma.c:2672 [inline] __mmap_region mm/vma.c:2755 [inline] mmap_region+0xe8b/0x2340 mm/vma.c:2857 do_mmap+0xc1e/0x10b0 mm/mmap.c:560 vm_mmap_pgoff+0x275/0x4e0 mm/util.c:581 ksys_mmap_pgoff+0x4a6/0x720 mm/mmap.c:606 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 RIP: 0033:0x7f07aaa2ce59 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:00007f07a8c7e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007f07aaca5fa0 RCX: 00007f07aaa2ce59 RDX: 0000000000000001 RSI: 0000000000004000 RDI: 0000200000000000 RBP: 00007f07aaac2d6f R08: 0000000000000007 R09: 0000000000000000 R10: 0000000000010012 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f07aaca6038 R14: 00007f07aaca5fa0 R15: 00007ffc1d310da8