====================================================== WARNING: possible circular locking dependency detected syzkaller #0 Not tainted ------------------------------------------------------ syz-executor.1/4985 is trying to acquire lock: ffff88802cfc63f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: __jbd2_log_wait_for_space+0x1a9/0x4c0 fs/jbd2/checkpoint.c:71 but task is already holding lock: ffff8880673e49b8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline] ffff8880673e49b8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_buffered_write_iter+0xa1/0x3a0 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+0x44/0x2e0 kernel/locking/rwsem.c:1498 inode_lock_shared include/linux/fs.h:797 [inline] ext4_bmap+0x4f/0x3f0 fs/ext4/inode.c:3166 bmap+0xa2/0xd0 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+0x7e0/0xcd0 fs/jbd2/journal.c:2517 ext4_ioctl_checkpoint fs/ext4/ioctl.c:856 [inline] __ext4_ioctl fs/ext4/ioctl.c:1282 [inline] ext4_ioctl+0x31f7/0x3840 fs/ext4/ioctl.c:1291 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:874 [inline] __se_sys_ioctl+0xfa/0x170 fs/ioctl.c:860 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x66/0xd0 -> #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+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596 mutex_lock_io_nested+0x43/0x60 kernel/locking/mutex.c:777 __jbd2_log_wait_for_space+0x1a9/0x4c0 fs/jbd2/checkpoint.c:71 add_transaction_credits+0x952/0xcb0 fs/jbd2/transaction.c:299 start_this_handle+0x723/0x1560 fs/jbd2/transaction.c:423 jbd2__journal_start+0x2b7/0x5a0 fs/jbd2/transaction.c:521 __ext4_journal_start_sb+0x167/0x360 fs/ext4/ext4_jbd2.c:105 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline] ext4_dirty_inode+0x8b/0x100 fs/ext4/inode.c:6074 __mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x3c0/0x440 fs/inode.c:2083 ext4_write_checks+0x23b/0x2c0 fs/ext4/file.c:247 ext4_buffered_write_iter+0xae/0x3a0 fs/ext4/file.c:263 ext4_file_write_iter+0x73f/0x1720 fs/ext4/file.c:-1 __kernel_write+0x522/0x980 fs/read_write.c:539 __dump_emit+0x258/0x380 fs/coredump.c:943 dump_user_range+0x84/0x340 fs/coredump.c:1017 elf_core_dump+0x2fe0/0x3530 fs/binfmt_elf.c:2285 do_coredump+0x14e8/0x2a40 fs/coredump.c:894 get_signal+0x531/0x12e0 kernel/signal.c:2895 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:320 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1499 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 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.1/4985: #0: ffff88802cfc2460 (sb_writers#5){.+.+}-{0:0}, at: do_coredump+0x14c4/0x2a40 fs/coredump.c:893 #1: ffff8880673e49b8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: inode_lock include/linux/fs.h:787 [inline] #1: ffff8880673e49b8 (&sb->s_type->i_mutex_key#9){++++}-{3:3}, at: ext4_buffered_write_iter+0xa1/0x3a0 fs/ext4/file.c:262 stack backtrace: CPU: 0 PID: 4985 Comm: syz-executor.1 Not tainted syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 Call Trace: dump_stack_lvl+0x188/0x250 lib/dump_stack.c:106 check_noncircular+0x296/0x330 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+0x2c66/0x7b50 kernel/locking/lockdep.c:5012 lock_acquire+0x19e/0x400 kernel/locking/lockdep.c:5623 __mutex_lock_common+0x1e5/0x2400 kernel/locking/mutex.c:596 mutex_lock_io_nested+0x43/0x60 kernel/locking/mutex.c:777 __jbd2_log_wait_for_space+0x1a9/0x4c0 fs/jbd2/checkpoint.c:71 add_transaction_credits+0x952/0xcb0 fs/jbd2/transaction.c:299 start_this_handle+0x723/0x1560 fs/jbd2/transaction.c:423 jbd2__journal_start+0x2b7/0x5a0 fs/jbd2/transaction.c:521 __ext4_journal_start_sb+0x167/0x360 fs/ext4/ext4_jbd2.c:105 __ext4_journal_start fs/ext4/ext4_jbd2.h:326 [inline] ext4_dirty_inode+0x8b/0x100 fs/ext4/inode.c:6074 __mark_inode_dirty+0x2c8/0xc90 fs/fs-writeback.c:2480 generic_update_time+0x1cd/0x1f0 fs/inode.c:1881 inode_update_time fs/inode.c:1894 [inline] file_update_time+0x3c0/0x440 fs/inode.c:2083 ext4_write_checks+0x23b/0x2c0 fs/ext4/file.c:247 ext4_buffered_write_iter+0xae/0x3a0 fs/ext4/file.c:263 ext4_file_write_iter+0x73f/0x1720 fs/ext4/file.c:-1 __kernel_write+0x522/0x980 fs/read_write.c:539 __dump_emit+0x258/0x380 fs/coredump.c:943 dump_user_range+0x84/0x340 fs/coredump.c:1017 elf_core_dump+0x2fe0/0x3530 fs/binfmt_elf.c:2285 do_coredump+0x14e8/0x2a40 fs/coredump.c:894 get_signal+0x531/0x12e0 kernel/signal.c:2895 arch_do_signal_or_restart+0xe6/0x12a0 arch/x86/kernel/signal.c:867 handle_signal_work kernel/entry/common.c:154 [inline] exit_to_user_mode_loop+0x9e/0x130 kernel/entry/common.c:178 exit_to_user_mode_prepare+0xee/0x180 kernel/entry/common.c:214 irqentry_exit_to_user_mode+0x5/0x30 kernel/entry/common.c:320 exc_page_fault+0x88/0x100 arch/x86/mm/fault.c:1499 asm_exc_page_fault+0x22/0x30 arch/x86/include/asm/idtentry.h:606 RIP: 0033:0x7f5bfdfca767 Code: 5a 0a 00 e8 3b fb ff ff 48 8d 3d d5 5a 0a 00 e8 2f fb ff ff 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 53 89 fb 48 83 ec 10 <64> 8b 04 25 b4 ff ff ff 85 c0 74 2a 89 fe 31 c0 bf 3c 00 00 00 e8 RSP: 002b:00007f5bfd3811a0 EFLAGS: 00010206 RAX: 0000000000000000 RBX: 000000000000000b RCX: 00007f5bfe0103b9 RDX: 00007f5bfd3811c0 RSI: 00007f5bfd3812f0 RDI: 000000000000000b RBP: 00007f5bfe0714c2 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 R13: 000000000000000b R14: 00007f5bfe14df80 R15: 00007ffd3f516928