====================================================== WARNING: possible circular locking dependency detected 5.15.181-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.4/4856 is trying to acquire lock: ffff0000d487e3f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: __jbd2_log_wait_for_space+0x178/0x51c fs/jbd2/checkpoint.c:71 but task is already holding lock: ffff0000e0f335c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline] ffff0000e0f335c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_buffered_write_iter+0x98/0x538 fs/ext4/file.c:262 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #1 (&sb->s_type->i_mutex_key#9){++++}-{3:3}: down_read+0xc0/0x390 kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] ext4_bmap+0x54/0x368 fs/ext4/inode.c:3164 bmap+0xa8/0xe8 fs/inode.c:1820 jbd2_journal_bmap fs/jbd2/journal.c:981 [inline] __jbd2_journal_erase fs/jbd2/journal.c:1795 [inline] jbd2_journal_flush+0x5e8/0x9f0 fs/jbd2/journal.c:2501 ext4_ioctl_checkpoint fs/ext4/ioctl.c:849 [inline] __ext4_ioctl fs/ext4/ioctl.c:1267 [inline] ext4_ioctl+0x2ca0/0x3600 fs/ext4/ioctl.c:1276 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl fs/ioctl.c:860 [inline] __arm64_sys_ioctl+0x14c/0x1c8 fs/ioctl.c:860 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline] invoke_syscall+0x98/0x2b8 arch/arm64/kernel/syscall.c:52 el0_svc_common+0x138/0x258 arch/arm64/kernel/syscall.c:142 do_el0_svc+0x58/0x14c arch/arm64/kernel/syscall.c:181 el0_svc+0x78/0x1e0 arch/arm64/kernel/entry-common.c:608 el0t_64_sync_handler+0xcc/0xe4 arch/arm64/kernel/entry-common.c:626 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 -> #0 (&journal->j_checkpoint_mutex){+.+.}-{3:3}: check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596 mutex_lock_io_nested+0xcc/0x12c kernel/locking/mutex.c:777 __jbd2_log_wait_for_space+0x178/0x51c fs/jbd2/checkpoint.c:71 add_transaction_credits+0x7cc/0xb58 fs/jbd2/transaction.c:299 start_this_handle+0x504/0x11a4 fs/jbd2/transaction.c:423 jbd2__journal_start+0x28c/0x744 fs/jbd2/transaction.c:521 __ext4_journal_start_sb+0x350/0x67c fs/ext4/ext4_jbd2.c:105 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline] ext4_dirty_inode+0x9c/0x100 fs/ext4/inode.c:6036 __mark_inode_dirty+0x2b0/0x1070 fs/fs-writeback.c:2464 generic_update_time+0x210/0x238 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x318/0x390 fs/inode.c:2083 file_modified+0x74/0xb4 fs/inode.c:2106 ext4_write_checks fs/ext4/file.c:247 [inline] ext4_buffered_write_iter+0x288/0x538 fs/ext4/file.c:263 ext4_file_write_iter+0x698/0x14cc include/linux/fs.h:-1 __kernel_write+0x3e8/0x7ac fs/read_write.c:539 __dump_emit+0x1dc/0x2fc fs/coredump.c:875 dump_emit+0x288/0x364 fs/coredump.c:912 dump_user_range+0xc8/0x354 fs/coredump.c:949 elf_core_dump+0x26d8/0x2bac fs/binfmt_elf.c:2285 do_coredump+0x1478/0x21d8 fs/coredump.c:826 get_signal+0x4f4/0x1340 kernel/signal.c:2886 do_signal arch/arm64/kernel/signal.c:893 [inline] do_notify_resume+0x29c/0x3128 arch/arm64/kernel/signal.c:946 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_da+0x10c/0x1fc arch/arm64/kernel/entry-common.c:495 el0t_64_sync_handler+0xd8/0xe4 arch/arm64/kernel/entry-common.c:629 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584 other info that might help us debug this: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&sb->s_type->i_mutex_key#9); lock(&journal->j_checkpoint_mutex); lock(&sb->s_type->i_mutex_key#9); lock(&journal->j_checkpoint_mutex); *** DEADLOCK *** 2 locks held by syz-executor.4/4856: #0: ffff0000d4878460 (sb_writers#3){.+.+}-{0:0}, at: do_coredump+0x1450/0x21d8 fs/coredump.c:825 #1: ffff0000e0f335c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline] #1: ffff0000e0f335c8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_buffered_write_iter+0x98/0x538 fs/ext4/file.c:262 stack backtrace: CPU: 1 PID: 4856 Comm: syz-executor.4 Not tainted 5.15.181-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025 Call trace: dump_backtrace+0x0/0x43c arch/arm64/kernel/stacktrace.c:152 show_stack+0x2c/0x3c arch/arm64/kernel/stacktrace.c:216 __dump_stack+0x30/0x40 lib/dump_stack.c:88 dump_stack_lvl+0xf8/0x160 lib/dump_stack.c:106 dump_stack+0x1c/0x5c lib/dump_stack.c:113 print_circular_bug+0x148/0x1b0 kernel/locking/lockdep.c:2011 check_noncircular+0x240/0x2d4 kernel/locking/lockdep.c:2133 check_prev_add kernel/locking/lockdep.c:3053 [inline] check_prevs_add kernel/locking/lockdep.c:3172 [inline] validate_chain kernel/locking/lockdep.c:3788 [inline] __lock_acquire+0x2928/0x651c kernel/locking/lockdep.c:5012 lock_acquire+0x1f4/0x620 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x194/0x1edc kernel/locking/mutex.c:596 mutex_lock_io_nested+0xcc/0x12c kernel/locking/mutex.c:777 __jbd2_log_wait_for_space+0x178/0x51c fs/jbd2/checkpoint.c:71 add_transaction_credits+0x7cc/0xb58 fs/jbd2/transaction.c:299 start_this_handle+0x504/0x11a4 fs/jbd2/transaction.c:423 jbd2__journal_start+0x28c/0x744 fs/jbd2/transaction.c:521 __ext4_journal_start_sb+0x350/0x67c fs/ext4/ext4_jbd2.c:105 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline] ext4_dirty_inode+0x9c/0x100 fs/ext4/inode.c:6036 __mark_inode_dirty+0x2b0/0x1070 fs/fs-writeback.c:2464 generic_update_time+0x210/0x238 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x318/0x390 fs/inode.c:2083 file_modified+0x74/0xb4 fs/inode.c:2106 ext4_write_checks fs/ext4/file.c:247 [inline] ext4_buffered_write_iter+0x288/0x538 fs/ext4/file.c:263 ext4_file_write_iter+0x698/0x14cc include/linux/fs.h:-1 __kernel_write+0x3e8/0x7ac fs/read_write.c:539 __dump_emit+0x1dc/0x2fc fs/coredump.c:875 dump_emit+0x288/0x364 fs/coredump.c:912 dump_user_range+0xc8/0x354 fs/coredump.c:949 elf_core_dump+0x26d8/0x2bac fs/binfmt_elf.c:2285 do_coredump+0x1478/0x21d8 fs/coredump.c:826 get_signal+0x4f4/0x1340 kernel/signal.c:2886 do_signal arch/arm64/kernel/signal.c:893 [inline] do_notify_resume+0x29c/0x3128 arch/arm64/kernel/signal.c:946 prepare_exit_to_user_mode arch/arm64/kernel/entry-common.c:133 [inline] exit_to_user_mode arch/arm64/kernel/entry-common.c:138 [inline] el0_da+0x10c/0x1fc arch/arm64/kernel/entry-common.c:495 el0t_64_sync_handler+0xd8/0xe4 arch/arm64/kernel/entry-common.c:629 el0t_64_sync+0x1a0/0x1a4 arch/arm64/kernel/entry.S:584