====================================================== WARNING: possible circular locking dependency detected 6.15.0-rc6-syzkaller-ga82e92598ab1 #0 Not tainted ------------------------------------------------------ syz.0.426/8764 is trying to acquire lock: ffff0000d7a956d0 (&mm->mmap_lock){++++}-{4:4}, at: mmap_read_lock_killable+0x28/0x31c include/linux/mmap_lock.h:193 but task is already holding lock: ffff0000c183b948 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x214/0x79c fs/kernfs/dir.c:1890 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&root->kernfs_rwsem){++++}-{4:4}: down_write+0x50/0xc0 kernel/locking/rwsem.c:1577 kernfs_add_one+0x48/0x60c fs/kernfs/dir.c:791 kernfs_create_dir_ns+0xd4/0x12c fs/kernfs/dir.c:1091 sysfs_create_dir_ns+0x114/0x24c fs/sysfs/dir.c:59 create_dir lib/kobject.c:73 [inline] kobject_add_internal+0x5a8/0xb20 lib/kobject.c:240 kobject_add_varg lib/kobject.c:374 [inline] kobject_init_and_add+0x118/0x17c lib/kobject.c:457 btrfs_sysfs_add_qgroups+0x10c/0x264 fs/btrfs/sysfs.c:2616 btrfs_quota_enable+0x224/0x1c6c fs/btrfs/qgroup.c:1030 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3676 btrfs_ioctl+0x86c/0xc38 fs/btrfs/ioctl.c:5326 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:892 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #3 (&fs_info->qgroup_ioctl_lock){+.+.}-{4:4}: __mutex_lock_common+0x1d0/0x2190 kernel/locking/mutex.c:601 __mutex_lock kernel/locking/mutex.c:746 [inline] mutex_lock_nested+0x2c/0x38 kernel/locking/mutex.c:798 btrfs_quota_enable+0x270/0x1c6c fs/btrfs/qgroup.c:1059 btrfs_ioctl_quota_ctl+0x178/0x1bc fs/btrfs/ioctl.c:3676 btrfs_ioctl+0x86c/0xc38 fs/btrfs/ioctl.c:5326 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:906 [inline] __se_sys_ioctl fs/ioctl.c:892 [inline] __arm64_sys_ioctl+0x14c/0x1c4 fs/ioctl.c:892 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #2 (btrfs_trans_num_extwriters){++++}-{0:0}: join_transaction+0x190/0xb5c fs/btrfs/transaction.c:321 start_transaction+0x778/0x1558 fs/btrfs/transaction.c:705 btrfs_start_transaction+0x34/0x44 fs/btrfs/transaction.c:815 btrfs_rebuild_free_space_tree+0xac/0x54c fs/btrfs/free-space-tree.c:1317 btrfs_start_pre_rw_mount+0xa78/0xe10 fs/btrfs/disk-io.c:3074 open_ctree+0x1b7c/0x229c fs/btrfs/disk-io.c:3614 btrfs_fill_super+0x184/0x2c0 fs/btrfs/super.c:972 btrfs_get_tree_super fs/btrfs/super.c:1897 [inline] btrfs_get_tree+0xc4c/0x1038 fs/btrfs/super.c:2092 vfs_get_tree+0x90/0x28c fs/super.c:1759 fc_mount+0x24/0xac fs/namespace.c:1289 btrfs_get_tree_subvol fs/btrfs/super.c:2050 [inline] btrfs_get_tree+0x4d4/0x1038 fs/btrfs/super.c:2093 vfs_get_tree+0x90/0x28c fs/super.c:1759 do_new_mount+0x228/0x814 fs/namespace.c:3881 path_mount+0x5b4/0xde0 fs/namespace.c:4208 do_mount fs/namespace.c:4221 [inline] __do_sys_mount fs/namespace.c:4432 [inline] __se_sys_mount fs/namespace.c:4409 [inline] __arm64_sys_mount+0x3e8/0x468 fs/namespace.c:4409 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #1 (btrfs_trans_num_writers){++++}-{0:0}: __lock_release kernel/locking/lockdep.c:5572 [inline] lock_release+0x198/0x39c kernel/locking/lockdep.c:5887 percpu_up_read include/linux/percpu-rwsem.h:100 [inline] __sb_end_write include/linux/fs.h:1778 [inline] sb_end_intwrite+0x3c/0x348 include/linux/fs.h:1895 __btrfs_end_transaction+0x1f4/0x5f0 fs/btrfs/transaction.c:1075 btrfs_end_transaction+0x24/0x34 fs/btrfs/transaction.c:1109 btrfs_dirty_inode+0x140/0x190 fs/btrfs/inode.c:6143 btrfs_update_time+0xa0/0xd0 fs/btrfs/inode.c:6163 inode_update_time fs/inode.c:2076 [inline] touch_atime+0x2e4/0x814 fs/inode.c:2149 file_accessed include/linux/fs.h:2599 [inline] btrfs_file_mmap+0xb0/0x11c fs/btrfs/file.c:1938 call_mmap include/linux/fs.h:2243 [inline] mmap_file mm/internal.h:167 [inline] __mmap_new_file_vma mm/vma.c:2353 [inline] __mmap_new_vma mm/vma.c:2417 [inline] __mmap_region mm/vma.c:2519 [inline] mmap_region+0xc34/0x1a24 mm/vma.c:2597 do_mmap+0x968/0xf78 mm/mmap.c:561 vm_mmap_pgoff+0x2b8/0x43c mm/util.c:579 ksys_mmap_pgoff+0x394/0x5b8 mm/mmap.c:607 __do_sys_mmap arch/arm64/kernel/sys.c:28 [inline] __se_sys_mmap arch/arm64/kernel/sys.c:21 [inline] __arm64_sys_mmap+0xf8/0x110 arch/arm64/kernel/sys.c:21 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 -> #0 (&mm->mmap_lock){++++}-{4:4}: check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1728/0x3058 kernel/locking/lockdep.c:5235 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5866 down_read_killable+0x60/0x32c kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x28/0x31c include/linux/mmap_lock.h:193 get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x2a4/0x2d8 mm/memory.c:6406 do_page_fault+0x51c/0x1554 arch/arm64/mm/fault.c:668 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:783 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:919 el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:455 el1h_64_sync_handler+0x50/0xcc arch/arm64/kernel/entry-common.c:533 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:595 __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:169 [inline] filldir64+0x2c8/0x698 fs/readdir.c:372 dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x498/0x79c fs/kernfs/dir.c:1907 iterate_dir+0x458/0x5e0 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:403 [inline] __se_sys_getdents64 fs/readdir.c:389 [inline] __arm64_sys_getdents64+0x114/0x2fc fs/readdir.c:389 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 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.0.426/8764: #0: ffff0000d9720638 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0x1fc/0x2a0 fs/file.c:1213 #1: ffff0000ddffc650 (&type->i_mutex_dir_key#6){++++}-{4:4}, at: iterate_dir+0x3a0/0x5e0 fs/readdir.c:101 #2: ffff0000c183b948 (&root->kernfs_rwsem){++++}-{4:4}, at: kernfs_fop_readdir+0x214/0x79c fs/kernfs/dir.c:1890 stack backtrace: CPU: 0 UID: 0 PID: 8764 Comm: syz.0.426 Not tainted 6.15.0-rc6-syzkaller-ga82e92598ab1 #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:466 (C) __dump_stack+0x30/0x40 lib/dump_stack.c:94 dump_stack_lvl+0xd8/0x12c lib/dump_stack.c:120 dump_stack+0x1c/0x28 lib/dump_stack.c:129 print_circular_bug+0x324/0x32c kernel/locking/lockdep.c:2079 check_noncircular+0x154/0x174 kernel/locking/lockdep.c:2211 check_prev_add kernel/locking/lockdep.c:3166 [inline] check_prevs_add kernel/locking/lockdep.c:3285 [inline] validate_chain kernel/locking/lockdep.c:3909 [inline] __lock_acquire+0x1728/0x3058 kernel/locking/lockdep.c:5235 lock_acquire+0x14c/0x2e0 kernel/locking/lockdep.c:5866 down_read_killable+0x60/0x32c kernel/locking/rwsem.c:1547 mmap_read_lock_killable+0x28/0x31c include/linux/mmap_lock.h:193 get_mmap_lock_carefully mm/memory.c:6355 [inline] lock_mm_and_find_vma+0x2a4/0x2d8 mm/memory.c:6406 do_page_fault+0x51c/0x1554 arch/arm64/mm/fault.c:668 do_translation_fault+0xc4/0x114 arch/arm64/mm/fault.c:783 do_mem_abort+0x70/0x194 arch/arm64/mm/fault.c:919 el1_abort+0x3c/0x5c arch/arm64/kernel/entry-common.c:455 el1h_64_sync_handler+0x50/0xcc arch/arm64/kernel/entry-common.c:533 el1h_64_sync+0x6c/0x70 arch/arm64/kernel/entry.S:595 __uaccess_mask_ptr arch/arm64/include/asm/uaccess.h:169 [inline] (P) filldir64+0x2c8/0x698 fs/readdir.c:372 (P) dir_emit include/linux/fs.h:3861 [inline] kernfs_fop_readdir+0x498/0x79c fs/kernfs/dir.c:1907 iterate_dir+0x458/0x5e0 fs/readdir.c:108 __do_sys_getdents64 fs/readdir.c:403 [inline] __se_sys_getdents64 fs/readdir.c:389 [inline] __arm64_sys_getdents64+0x114/0x2fc fs/readdir.c:389 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:49 el0_svc_common+0x130/0x23c arch/arm64/kernel/syscall.c:132 do_el0_svc+0x48/0x58 arch/arm64/kernel/syscall.c:151 el0_svc+0x58/0x17c arch/arm64/kernel/entry-common.c:767 el0t_64_sync_handler+0x78/0x108 arch/arm64/kernel/entry-common.c:786 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:600 loop0: detected capacity change from 0 to 32768 BTRFS: device fsid ed167579-eb65-4e76-9a50-61ac97e9b59d devid 1 transid 8 /dev/loop0 (7:0) scanned by syz.0.426 (8764) BTRFS info (device loop0): first mount of filesystem ed167579-eb65-4e76-9a50-61ac97e9b59d BTRFS info (device loop0): using sha256 (sha256-ce) checksum algorithm BTRFS info (device loop0): using free-space-tree BTRFS info (device loop0): rebuilding free space tree