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12:02:24 -0700 (PDT) Date: Mon, 08 Aug 2022 12:02:24 -0700 In-Reply-To: <000000000000967c2805e5b5d4ed@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000cec16b05e5bf7409@google.com> Subject: Re: [syzbot] possible deadlock in ext4_bmap From: syzbot To: adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tytso@mit.edu Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org syzbot has found a reproducer for the following issue on: HEAD commit: ca688bff68bc Add linux-next specific files for 20220808 git tree: linux-next console+strace: https://syzkaller.appspot.com/x/log.txt?x=15a71e71080000 kernel config: https://syzkaller.appspot.com/x/.config?x=4c20e006003cdecb dashboard link: https://syzkaller.appspot.com/bug?extid=9543479984ae9e576000 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1551c53e080000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14fcdbfa080000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+9543479984ae9e576000@syzkaller.appspotmail.com warning: checkpointing journal with EXT4_IOC_CHECKPOINT_FLAG_ZEROOUT can be slow ====================================================== WARNING: possible circular locking dependency detected 5.19.0-next-20220808-syzkaller #0 Not tainted ------------------------------------------------------ syz-executor725/3607 is trying to acquire lock: ffff888144c48400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: inode_lock_shared include/linux/fs.h:771 [inline] ffff888144c48400 (&sb->s_type->i_mutex_key#8){++++}-{3:3}, at: ext4_bmap+0x4e/0x460 fs/ext4/inode.c:3157 but task is already holding lock: ffff88807ec503f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x487/0xc00 fs/jbd2/journal.c:2472 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&journal->j_checkpoint_mutex){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] mutex_lock_io_nested+0x13f/0x1190 kernel/locking/mutex.c:833 jbd2_journal_flush+0x19a/0xc00 fs/jbd2/journal.c:2462 ext4_ioctl_checkpoint fs/ext4/ioctl.c:1082 [inline] __ext4_ioctl+0x28fd/0x4ab0 fs/ext4/ioctl.c:1586 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #2 (&journal->j_barrier){+.+.}-{3:3}: __mutex_lock_common kernel/locking/mutex.c:603 [inline] __mutex_lock+0x12f/0x1350 kernel/locking/mutex.c:747 jbd2_journal_lock_updates+0x15e/0x310 fs/jbd2/transaction.c:904 ext4_change_inode_journal_flag+0x180/0x530 fs/ext4/inode.c:6014 ext4_ioctl_setflags fs/ext4/ioctl.c:685 [inline] ext4_fileattr_set+0xddf/0x1930 fs/ext4/ioctl.c:1001 vfs_fileattr_set+0x7f5/0xbe0 fs/ioctl.c:696 ioctl_fssetxattr fs/ioctl.c:758 [inline] do_vfs_ioctl+0xe62/0x15c0 fs/ioctl.c:845 __do_sys_ioctl fs/ioctl.c:868 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x108/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #1 (&sbi->s_writepages_rwsem){++++}-{0:0}: percpu_down_write+0x4d/0x440 kernel/locking/percpu-rwsem.c:221 ext4_ind_migrate+0x237/0x840 fs/ext4/migrate.c:624 ext4_ioctl_setflags fs/ext4/ioctl.c:694 [inline] ext4_fileattr_set+0x14b8/0x1930 fs/ext4/ioctl.c:1001 vfs_fileattr_set+0x7f5/0xbe0 fs/ioctl.c:696 ioctl_fssetxattr fs/ioctl.c:758 [inline] do_vfs_ioctl+0xe62/0x15c0 fs/ioctl.c:845 __do_sys_ioctl fs/ioctl.c:868 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x108/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd -> #0 (&sb->s_type->i_mutex_key#8){++++}-{3:3}: check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3829 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 down_read+0x98/0x450 kernel/locking/rwsem.c:1499 inode_lock_shared include/linux/fs.h:771 [inline] ext4_bmap+0x4e/0x460 fs/ext4/inode.c:3157 bmap+0xaa/0x120 fs/inode.c:1799 jbd2_journal_bmap+0xa8/0x180 fs/jbd2/journal.c:971 __jbd2_journal_erase fs/jbd2/journal.c:1784 [inline] jbd2_journal_flush+0x84f/0xc00 fs/jbd2/journal.c:2490 ext4_ioctl_checkpoint fs/ext4/ioctl.c:1082 [inline] __ext4_ioctl+0x28fd/0x4ab0 fs/ext4/ioctl.c:1586 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd other info that might help us debug this: Chain exists of: &sb->s_type->i_mutex_key#8 --> &journal->j_barrier --> &journal->j_checkpoint_mutex Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&journal->j_checkpoint_mutex); lock(&journal->j_barrier); lock(&journal->j_checkpoint_mutex); lock(&sb->s_type->i_mutex_key#8); *** DEADLOCK *** 2 locks held by syz-executor725/3607: #0: ffff88807ec50170 (&journal->j_barrier){+.+.}-{3:3}, at: jbd2_journal_lock_updates+0x15e/0x310 fs/jbd2/transaction.c:904 #1: ffff88807ec503f8 (&journal->j_checkpoint_mutex){+.+.}-{3:3}, at: jbd2_journal_flush+0x487/0xc00 fs/jbd2/journal.c:2472 stack backtrace: CPU: 1 PID: 3607 Comm: syz-executor725 Not tainted 5.19.0-next-20220808-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/22/2022 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106 check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2175 check_prev_add kernel/locking/lockdep.c:3095 [inline] check_prevs_add kernel/locking/lockdep.c:3214 [inline] validate_chain kernel/locking/lockdep.c:3829 [inline] __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5053 lock_acquire kernel/locking/lockdep.c:5666 [inline] lock_acquire+0x1ab/0x570 kernel/locking/lockdep.c:5631 down_read+0x98/0x450 kernel/locking/rwsem.c:1499 inode_lock_shared include/linux/fs.h:771 [inline] ext4_bmap+0x4e/0x460 fs/ext4/inode.c:3157 bmap+0xaa/0x120 fs/inode.c:1799 jbd2_journal_bmap+0xa8/0x180 fs/jbd2/journal.c:971 __jbd2_journal_erase fs/jbd2/journal.c:1784 [inline] jbd2_journal_flush+0x84f/0xc00 fs/jbd2/journal.c:2490 ext4_ioctl_checkpoint fs/ext4/ioctl.c:1082 [inline] __ext4_ioctl+0x28fd/0x4ab0 fs/ext4/ioctl.c:1586 vfs_ioctl fs/ioctl.c:51 [inline] __do_sys_ioctl fs/ioctl.c:870 [inline] __se_sys_ioctl fs/ioctl.c:856 [inline] __x64_sys_ioctl+0x193/0x200 fs/ioctl.c:856 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7fe2d1101d69 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 b1 14 00 00 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 c0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007ffd7aba8f78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010 RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe2d1101d69 RDX: 0000000020000000 RSI: 000000004004662b RDI: 0000000000000004 RBP: 0000000000000000 R08: 00007ffd7aba9118 R09: 00007ffd7aba9118 R10: 00007ffd7aba9118 R11: 0000000000000246 R12: 00007fe2d10c55f0 R13: 431bde82d7b634db R14: 0000000000000000 R15: 0000000000000000