====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.2.1395/20347 is trying to acquire lock: ffff88803b3fe800 (sb_internal#2){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6434 but task is already holding lock: ffff88803b61ba30 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline] ffff88803b61ba30 (&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:1599 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+0x343/0x1340 arch/x86/mm/fault.c:1366 handle_page_fault arch/x86/mm/fault.c:1483 [inline] exc_page_fault+0x6a/0xc0 arch/x86/mm/fault.c:1536 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:595 filldir+0x2bd/0x630 fs/readdir.c:-1 dir_emit include/linux/fs.h:3593 [inline] kernfs_fop_readdir+0x583/0x960 fs/kernfs/dir.c:1999 iterate_dir+0x2f1/0x4e0 fs/readdir.c:110 __do_sys_getdents fs/readdir.c:319 [inline] __se_sys_getdents+0xf1/0x270 fs/readdir.c:304 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #4 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x3a/0x50 kernel/locking/rwsem.c:1631 kernfs_add_one+0x41/0x5e0 fs/kernfs/dir.c:825 kernfs_create_dir_ns+0x1a1/0x230 fs/kernfs/dir.c:1130 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+0x274/0x1e20 fs/btrfs/qgroup.c:1032 btrfs_ioctl_quota_ctl+0x189/0x1f0 fs/btrfs/ioctl.c:3568 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:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common kernel/locking/rtmutex_api.c:559 [inline] mutex_lock_nested+0x5a/0x1d0 kernel/locking/rtmutex_api.c:578 btrfs_quota_enable+0x2b1/0x1e20 fs/btrfs/qgroup.c:1061 btrfs_ioctl_quota_ctl+0x189/0x1f0 fs/btrfs/ioctl.c:3568 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:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 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+0x742/0x1890 fs/btrfs/transaction.c:720 btrfs_create_common+0x15c/0x310 fs/btrfs/inode.c:6972 btrfs_mkdir+0xc1/0xf0 fs/btrfs/inode.c:7117 vfs_mkdir+0x408/0x620 fs/namei.c:5410 filename_mkdirat+0x289/0x520 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 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+0x742/0x1890 fs/btrfs/transaction.c:720 btrfs_create_common+0x15c/0x310 fs/btrfs/inode.c:6972 btrfs_mkdir+0xc1/0xf0 fs/btrfs/inode.c:7117 vfs_mkdir+0x408/0x620 fs/namei.c:5410 filename_mkdirat+0x289/0x520 fs/namei.c:5443 __do_sys_mkdirat fs/namei.c:5464 [inline] __se_sys_mkdirat+0x35/0x150 fs/namei.c:5461 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f -> #0 (sb_internal#2){.+.+}-{0:0}: check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5253 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886 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+0x5ca/0x1890 fs/btrfs/transaction.c:714 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6434 touch_atime+0x2f8/0x670 fs/inode.c:2326 file_accessed include/linux/fs.h:2278 [inline] btrfs_file_mmap_prepare+0x189/0x200 fs/btrfs/file.c:2029 vfs_mmap_prepare include/linux/fs.h:2070 [inline] call_mmap_prepare mm/vma.c:2672 [inline] __mmap_region mm/vma.c:2758 [inline] mmap_region+0xe78/0x2310 mm/vma.c:2860 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:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f other info that might help us debug this: Chain exists of: sb_internal#2 --> &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#2); *** DEADLOCK *** locks held by syz.2.1395/20347: 2, last CPU#0: #0: ffff88803b61ba30 (&mm->mmap_lock){++++}-{4:4}, at: mmap_write_lock_killable include/linux/mmap_lock.h:554 [inline] #0: ffff88803b61ba30 (&mm->mmap_lock){++++}-{4:4}, at: vm_mmap_pgoff+0x1e0/0x4e0 mm/util.c:579 #1: ffff88803b3fe510 (sb_writers#11){.+.+}-{0:0}, at: file_accessed include/linux/fs.h:2278 [inline] #1: ffff88803b3fe510 (sb_writers#11){.+.+}-{0:0}, at: btrfs_file_mmap_prepare+0x189/0x200 fs/btrfs/file.c:2029 stack backtrace: CPU: 0 UID: 0 PID: 20347 Comm: syz.2.1395 Not tainted syzkaller #0 PREEMPT_{RT,(full)} Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0xe8/0x150 lib/dump_stack.c:120 print_circular_bug+0x2e1/0x300 kernel/locking/lockdep.c:2059 check_noncircular+0x12e/0x150 kernel/locking/lockdep.c:2191 check_prev_add kernel/locking/lockdep.c:3181 [inline] check_prevs_add kernel/locking/lockdep.c:3300 [inline] validate_chain kernel/locking/lockdep.c:3924 [inline] __lock_acquire+0x1520/0x2ce0 kernel/locking/lockdep.c:5253 lock_acquire+0x106/0x350 kernel/locking/lockdep.c:5886 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+0x5ca/0x1890 fs/btrfs/transaction.c:714 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6434 touch_atime+0x2f8/0x670 fs/inode.c:2326 file_accessed include/linux/fs.h:2278 [inline] btrfs_file_mmap_prepare+0x189/0x200 fs/btrfs/file.c:2029 vfs_mmap_prepare include/linux/fs.h:2070 [inline] call_mmap_prepare mm/vma.c:2672 [inline] __mmap_region mm/vma.c:2758 [inline] mmap_region+0xe78/0x2310 mm/vma.c:2860 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:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ffa136ae0d9 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:00007ffa118e5028 EFLAGS: 00000246 ORIG_RAX: 0000000000000009 RAX: ffffffffffffffda RBX: 00007ffa13936090 RCX: 00007ffa136ae0d9 RDX: 0000000000000001 RSI: 0000000000400000 RDI: 0000200000000000 RBP: 00007ffa13745024 R08: 0000000000000004 R09: 0000000000000000 R10: 0000000000010012 R11: 0000000000000246 R12: 0000000000000000 R13: 00007ffa13936128 R14: 00007ffa13936090 R15: 00007ffcb92dd308