====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.4.171/7210 is trying to acquire lock: ffff88803ac74770 (sb_internal#5){.+.+}-{0:0}, at: btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6429 but task is already holding lock: ffff88803ac745f8 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x150/0x310 mm/memory.c:3589 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #6 (sb_pagefaults#3){.+.+}-{0:0}: 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_pagefault include/linux/fs/super.h:159 [inline] btrfs_page_mkwrite+0x329/0x1b10 fs/btrfs/file.c:1873 do_page_mkwrite+0x150/0x310 mm/memory.c:3589 wp_page_shared mm/memory.c:3990 [inline] do_wp_page+0x203b/0x49d0 mm/memory.c:4209 handle_pte_fault mm/memory.c:6333 [inline] __handle_mm_fault mm/memory.c:6455 [inline] handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6624 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334 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 -> #5 (vm_lock){++++}-{0:0}: __vma_start_exclude_readers+0x28a/0x940 mm/mmap_lock.c:125 __vma_start_write+0xdc/0x290 mm/mmap_lock.c:148 vma_start_write include/linux/mmap_lock.h:303 [inline] mprotect_fixup+0x5ee/0xa80 mm/mprotect.c:768 setup_arg_pages+0x565/0xac0 fs/exec.c:670 load_elf_binary+0xc67/0x29b0 fs/binfmt_elf.c:1029 search_binary_handler fs/exec.c:1664 [inline] exec_binprm fs/exec.c:1696 [inline] bprm_execve+0x93d/0x1460 fs/exec.c:1748 kernel_execve+0x844/0x930 fs/exec.c:1892 try_to_run_init_process+0x13/0x60 init/main.c:1510 kernel_init+0xad/0x1d0 init/main.c:1638 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 -> #4 (&mm->mmap_lock){++++}-{4:4}: 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 -> #3 (&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_add+0x163/0x240 lib/kobject.c:426 btrfs_sysfs_add_block_group_type+0x243/0x6c0 fs/btrfs/sysfs.c:1866 btrfs_create_pending_block_groups+0xd3d/0x1a00 fs/btrfs/block-group.c:2876 __btrfs_end_transaction+0x140/0x640 fs/btrfs/transaction.c:1080 btrfs_inc_block_group_ro+0x63e/0x6f0 fs/btrfs/block-group.c:3150 btrfs_relocate_block_group+0x26d/0x980 fs/btrfs/relocation.c:5355 btrfs_relocate_chunk+0x115/0x830 fs/btrfs/volumes.c:3590 __btrfs_balance+0x1dbf/0x2af0 fs/btrfs/volumes.c:4492 btrfs_balance+0xafa/0x11f0 fs/btrfs/volumes.c:4879 btrfs_ioctl_balance+0x3d6/0x610 fs/btrfs/ioctl.c:3452 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_rebuild_free_space_tree+0xbb/0x6e0 fs/btrfs/free-space-tree.c:1328 btrfs_start_pre_rw_mount+0x1529/0x1f20 fs/btrfs/disk-io.c:3060 open_ctree+0x2e07/0x4220 fs/btrfs/disk-io.c:3657 btrfs_fill_super fs/btrfs/super.c:981 [inline] btrfs_get_tree_super fs/btrfs/super.c:1944 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline] btrfs_get_tree+0x1061/0x1930 fs/btrfs/super.c:2121 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3763 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3839 do_mount fs/namespace.c:4172 [inline] __do_sys_mount fs/namespace.c:4361 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4338 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}: join_transaction+0x182/0xc90 fs/btrfs/transaction.c:322 start_transaction+0x6b9/0x1650 fs/btrfs/transaction.c:708 btrfs_rebuild_free_space_tree+0xbb/0x6e0 fs/btrfs/free-space-tree.c:1328 btrfs_start_pre_rw_mount+0x1529/0x1f20 fs/btrfs/disk-io.c:3060 open_ctree+0x2e07/0x4220 fs/btrfs/disk-io.c:3657 btrfs_fill_super fs/btrfs/super.c:981 [inline] btrfs_get_tree_super fs/btrfs/super.c:1944 [inline] btrfs_get_tree_subvol fs/btrfs/super.c:2087 [inline] btrfs_get_tree+0x1061/0x1930 fs/btrfs/super.c:2121 vfs_get_tree+0x92/0x2a0 fs/super.c:1754 fc_mount fs/namespace.c:1193 [inline] do_new_mount_fc fs/namespace.c:3763 [inline] do_new_mount+0x341/0xd30 fs/namespace.c:3839 do_mount fs/namespace.c:4172 [inline] __do_sys_mount fs/namespace.c:4361 [inline] __se_sys_mount+0x31d/0x420 fs/namespace.c:4338 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 (sb_internal#5){.+.+}-{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+0x15a5/0x2cf0 kernel/locking/lockdep.c:5237 lock_acquire+0xf0/0x2e0 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+0x56e/0x1650 fs/btrfs/transaction.c:702 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6429 file_update_time_flags+0x2d5/0x4b0 fs/inode.c:2426 btrfs_page_mkwrite+0x5df/0x1b10 fs/btrfs/file.c:1914 do_page_mkwrite+0x150/0x310 mm/memory.c:3589 wp_page_shared mm/memory.c:3990 [inline] do_wp_page+0x203b/0x49d0 mm/memory.c:4209 handle_pte_fault mm/memory.c:6333 [inline] __handle_mm_fault mm/memory.c:6455 [inline] handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6624 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334 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 other info that might help us debug this: Chain exists of: sb_internal#5 --> vm_lock --> sb_pagefaults#3 Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(sb_pagefaults#3); lock(vm_lock); lock(sb_pagefaults#3); rlock(sb_internal#5); *** DEADLOCK *** 2 locks held by syz.4.171/7210: #0: ffff88802f47b948 (vm_lock){++++}-{0:0}, at: lock_vma_under_rcu+0x1d1/0x500 mm/mmap_lock.c:310 #1: ffff88803ac745f8 (sb_pagefaults#3){.+.+}-{0:0}, at: do_page_mkwrite+0x150/0x310 mm/memory.c:3589 stack backtrace: CPU: 1 UID: 0 PID: 7210 Comm: syz.4.171 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 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+0x56e/0x1650 fs/btrfs/transaction.c:702 btrfs_dirty_inode+0x9f/0x190 fs/btrfs/inode.c:6429 file_update_time_flags+0x2d5/0x4b0 fs/inode.c:2426 btrfs_page_mkwrite+0x5df/0x1b10 fs/btrfs/file.c:1914 do_page_mkwrite+0x150/0x310 mm/memory.c:3589 wp_page_shared mm/memory.c:3990 [inline] do_wp_page+0x203b/0x49d0 mm/memory.c:4209 handle_pte_fault mm/memory.c:6333 [inline] __handle_mm_fault mm/memory.c:6455 [inline] handle_mm_fault+0x9f5/0x13c0 mm/memory.c:6624 do_user_addr_fault+0xa73/0x1340 arch/x86/mm/fault.c:1334 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: 0033:0x7f5c00a69cb8 Code: 25 00 00 00 00 48 8d b8 d8 fe ff ff 4c 89 74 24 50 e8 5c 3b 0d 00 85 c0 75 13 48 8b 84 24 80 00 00 00 48 8b b4 24 c0 00 00 00 <48> 89 30 64 f0 83 2c 25 a0 ff ff ff 01 4c 8b 74 24 50 e9 91 f5 ff RSP: 002b:00007ffe65b59540 EFLAGS: 00010246 RAX: 00002000000000c0 RBX: 0000000000000002 RCX: 0000000000000007 RDX: f4c482c00a724f7c RSI: 0000200000000300 RDI: 00005555786933d8 RBP: fffffffffffffffe R08: 0000001b2e320000 R09: 000000000000000c R10: 0000000000000300 R11: 0000000000000001 R12: 00007ffe65b59660 R13: 00007f5c00e15fac R14: 000000000002e13a R15: 00007f5c00e15fa0