====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz.0.77/5160 is trying to acquire lock: ffff0000f2315e80 (&ei->xattr_sem){++++}-{4:4}, at: ext4_write_lock_xattr fs/ext4/xattr.h:157 [inline] ffff0000f2315e80 (&ei->xattr_sem){++++}-{4:4}, at: ext4_destroy_inline_data+0x30/0x114 fs/ext4/inline.c:1805 but task is already holding lock: ffff0000c74b8c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: percpu_down_read include/linux/percpu-rwsem.h:77 [inline] ffff0000c74b8c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1876 [inline] ffff0000c74b8c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x170/0x2dc fs/ext4/inode.c:3042 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}: percpu_down_read_internal+0x5c/0x294 include/linux/percpu-rwsem.h:53 percpu_down_read include/linux/percpu-rwsem.h:77 [inline] ext4_writepages_down_read fs/ext4/ext4.h:1876 [inline] ext4_writepages+0x170/0x2dc fs/ext4/inode.c:3042 do_writepages+0x284/0x47c mm/page-writeback.c:2571 __writeback_single_inode+0x140/0x1880 fs/fs-writeback.c:1787 writeback_single_inode+0x400/0xb20 fs/fs-writeback.c:1906 write_inode_now+0x170/0x208 fs/fs-writeback.c:3060 iput_final fs/inode.c:2009 [inline] iput+0x7cc/0xc2c fs/inode.c:2068 ext4_xattr_block_set+0x1460/0x21e8 fs/ext4/xattr.c:2206 ext4_xattr_move_to_block fs/ext4/xattr.c:2671 [inline] ext4_xattr_make_inode_space fs/ext4/xattr.c:2746 [inline] ext4_expand_extra_isize_ea+0xaf4/0x1384 fs/ext4/xattr.c:2834 __ext4_expand_extra_isize+0x2a4/0x378 fs/ext4/inode.c:6486 ext4_try_to_expand_extra_isize fs/ext4/inode.c:6529 [inline] __ext4_mark_inode_dirty+0x394/0x828 fs/ext4/inode.c:6607 ext4_evict_inode+0x798/0xfb8 fs/ext4/inode.c:267 evict+0x4c0/0x74c fs/inode.c:825 iput_final fs/inode.c:2019 [inline] iput+0x8f0/0xc2c fs/inode.c:2068 ext4_process_orphan+0x24c/0x2c0 fs/ext4/orphan.c:358 ext4_orphan_cleanup+0x7d4/0xd20 fs/ext4/orphan.c:472 __ext4_fill_super fs/ext4/super.c:5705 [inline] ext4_fill_super+0x4628/0x4e14 fs/ext4/super.c:5828 get_tree_bdev_flags+0x388/0x43c fs/super.c:1634 get_tree_bdev+0x2c/0x3c fs/super.c:1657 ext4_get_tree+0x28/0x38 fs/ext4/super.c:5860 vfs_get_tree+0x90/0x28c fs/super.c:1694 fc_mount+0x24/0xac fs/namespace.c:1198 do_new_mount_fc fs/namespace.c:3765 [inline] do_new_mount+0x2a4/0x538 fs/namespace.c:3841 path_mount+0x5f0/0xa88 fs/namespace.c:4161 do_mount+0xe8/0x148 fs/namespace.c:4174 __do_sys_mount fs/namespace.c:4390 [inline] __se_sys_mount fs/namespace.c:4367 [inline] __arm64_sys_mount+0x334/0x380 fs/namespace.c:4367 __invoke_syscall arch/arm64/kernel/syscall.c:35 [inline] invoke_syscall+0x98/0x244 arch/arm64/kernel/syscall.c:49 el0_svc_common+0xec/0x23c arch/arm64/kernel/syscall.c:121 do_el0_svc+0x4c/0x5c arch/arm64/kernel/syscall.c:140 el0_svc+0x64/0x260 arch/arm64/kernel/entry-common.c:736 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 -> #0 (&ei->xattr_sem){++++}-{4:4}: 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+0x17c0/0x2ebc kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868 down_write+0x50/0xc0 kernel/locking/rwsem.c:1631 ext4_write_lock_xattr fs/ext4/xattr.h:157 [inline] ext4_destroy_inline_data+0x30/0x114 fs/ext4/inline.c:1805 ext4_do_writepages+0x3e4/0x3bc0 fs/ext4/inode.c:2828 ext4_writepages+0x198/0x2dc fs/ext4/inode.c:3043 do_writepages+0x284/0x47c mm/page-writeback.c:2571 filemap_writeback+0x230/0x2bc mm/filemap.c:387 filemap_flush_range mm/filemap.c:436 [inline] filemap_flush+0x30/0x40 mm/filemap.c:451 ext4_alloc_da_blocks+0x104/0x414 fs/ext4/inode.c:3354 ext4_release_file+0x68/0x2c0 fs/ext4/file.c:169 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&sbi->s_writepages_rwsem); lock(&ei->xattr_sem); lock(&sbi->s_writepages_rwsem); lock(&ei->xattr_sem); *** DEADLOCK *** 1 lock held by syz.0.77/5160: #0: ffff0000c74b8c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: percpu_down_read include/linux/percpu-rwsem.h:77 [inline] #0: ffff0000c74b8c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages_down_read fs/ext4/ext4.h:1876 [inline] #0: ffff0000c74b8c18 (&sbi->s_writepages_rwsem){++++}-{0:0}, at: ext4_writepages+0x170/0x2dc fs/ext4/inode.c:3042 stack backtrace: CPU: 1 UID: 0 PID: 5160 Comm: syz.0.77 Not tainted syzkaller #0 PREEMPT Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/02/2026 Call trace: show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:499 (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+0x328/0x330 kernel/locking/lockdep.c:2043 check_noncircular+0x158/0x174 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+0x17c0/0x2ebc kernel/locking/lockdep.c:5237 lock_acquire+0x140/0x364 kernel/locking/lockdep.c:5868 down_write+0x50/0xc0 kernel/locking/rwsem.c:1631 ext4_write_lock_xattr fs/ext4/xattr.h:157 [inline] ext4_destroy_inline_data+0x30/0x114 fs/ext4/inline.c:1805 ext4_do_writepages+0x3e4/0x3bc0 fs/ext4/inode.c:2828 ext4_writepages+0x198/0x2dc fs/ext4/inode.c:3043 do_writepages+0x284/0x47c mm/page-writeback.c:2571 filemap_writeback+0x230/0x2bc mm/filemap.c:387 filemap_flush_range mm/filemap.c:436 [inline] filemap_flush+0x30/0x40 mm/filemap.c:451 ext4_alloc_da_blocks+0x104/0x414 fs/ext4/inode.c:3354 ext4_release_file+0x68/0x2c0 fs/ext4/file.c:169 __fput+0x338/0x74c fs/file_table.c:512 ____fput+0x20/0x30 fs/file_table.c:540 task_work_run+0x1cc/0x25c kernel/task_work.c:233 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline] __exit_to_user_mode_loop kernel/entry/common.c:70 [inline] exit_to_user_mode_loop+0x10c/0x17c kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] arm64_syscall_exit_to_user_mode arch/arm64/kernel/entry-common.c:88 [inline] el0_svc+0x18c/0x260 arch/arm64/kernel/entry-common.c:737 el0t_64_sync_handler+0x48/0x148 arch/arm64/kernel/entry-common.c:755 el0t_64_sync+0x198/0x19c arch/arm64/kernel/entry.S:594 EXT4-fs error (device loop0): ext4_mb_generate_buddy:1317: group 0, block bitmap and bg descriptor inconsistent: 25 vs 150994969 free clusters EXT4-fs (loop0): Delayed block allocation failed for inode 15 at logical offset 0 with max blocks 1 with error 28 EXT4-fs (loop0): This should not happen!! Data will be lost EXT4-fs (loop0): Total free blocks count 0 EXT4-fs (loop0): Free/Dirty block details EXT4-fs (loop0): free_blocks=2415919104 EXT4-fs (loop0): dirty_blocks=16 EXT4-fs (loop0): Block reservation details EXT4-fs (loop0): i_reserved_data_blocks=1