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Thu, 12 Aug 2021 06:53:18 -0700 (PDT) Date: Thu, 12 Aug 2021 06:53:18 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <000000000000a4cc9405c95d0e1c@google.com> Subject: [syzbot] possible deadlock in fuse_reverse_inval_entry From: syzbot To: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, miklos@szeredi.hu, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, syzbot found the following issue on: HEAD commit: 85a90500f9a1 Merge tag 'io_uring-5.14-2021-08-07' of git:/.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10bc00c2300000 kernel config: https://syzkaller.appspot.com/x/.config?x=343fd21f6f4da2d6 dashboard link: https://syzkaller.appspot.com/bug?extid=9f747458f5990eaa8d43 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1427c9aa300000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1540a2f6300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+9f747458f5990eaa8d43@syzkaller.appspotmail.com ============================================ WARNING: possible recursive locking detected 5.14.0-rc4-syzkaller #0 Not tainted -------------------------------------------- syz-executor799/8433 is trying to acquire lock: ffff888039930ed0 (&type->i_mutex_dir_key#7){++++}-{3:3}, at: inode_lock include/linux/fs.h:774 [inline] ffff888039930ed0 (&type->i_mutex_dir_key#7){++++}-{3:3}, at: fuse_reverse_inval_entry+0x1f5/0x530 fs/fuse/dir.c:1093 but task is already holding lock: ffff888039930150 (&type->i_mutex_dir_key#7){++++}-{3:3}, at: inode_lock include/linux/fs.h:774 [inline] ffff888039930150 (&type->i_mutex_dir_key#7){++++}-{3:3}, at: fuse_reverse_inval_entry+0x4c/0x530 fs/fuse/dir.c:1074 other info that might help us debug this: Possible unsafe locking scenario: CPU0 ---- lock(&type->i_mutex_dir_key#7); lock(&type->i_mutex_dir_key#7); *** DEADLOCK *** May be due to missing lock nesting notation 2 locks held by syz-executor799/8433: #0: ffff888022b6bb38 (&fc->killsb){.+.+}-{3:3}, at: fuse_notify_delete fs/fuse/dev.c:1540 [inline] #0: ffff888022b6bb38 (&fc->killsb){.+.+}-{3:3}, at: fuse_notify fs/fuse/dev.c:1790 [inline] #0: ffff888022b6bb38 (&fc->killsb){.+.+}-{3:3}, at: fuse_dev_do_write+0x285f/0x2bd0 fs/fuse/dev.c:1865 #1: ffff888039930150 (&type->i_mutex_dir_key#7){++++}-{3:3}, at: inode_lock include/linux/fs.h:774 [inline] #1: ffff888039930150 (&type->i_mutex_dir_key#7){++++}-{3:3}, at: fuse_reverse_inval_entry+0x4c/0x530 fs/fuse/dir.c:1074 stack backtrace: CPU: 1 PID: 8433 Comm: syz-executor799 Not tainted 5.14.0-rc4-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:105 print_deadlock_bug kernel/locking/lockdep.c:2944 [inline] check_deadlock kernel/locking/lockdep.c:2987 [inline] validate_chain kernel/locking/lockdep.c:3776 [inline] __lock_acquire.cold+0x149/0x3ab kernel/locking/lockdep.c:5015 lock_acquire kernel/locking/lockdep.c:5625 [inline] lock_acquire+0x1ab/0x510 kernel/locking/lockdep.c:5590 down_write+0x92/0x150 kernel/locking/rwsem.c:1406 inode_lock include/linux/fs.h:774 [inline] fuse_reverse_inval_entry+0x1f5/0x530 fs/fuse/dir.c:1093 fuse_notify_delete fs/fuse/dev.c:1541 [inline] fuse_notify fs/fuse/dev.c:1790 [inline] fuse_dev_do_write+0x287f/0x2bd0 fs/fuse/dev.c:1865 fuse_dev_write+0x144/0x1d0 fs/fuse/dev.c:1949 call_write_iter include/linux/fs.h:2114 [inline] new_sync_write+0x426/0x650 fs/read_write.c:518 vfs_write+0x75a/0xa40 fs/read_write.c:605 ksys_write+0x12d/0x250 fs/read_write.c:658 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+0x44/0xae RIP: 0033:0x4455e9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 81 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 b8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f64ac9752f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001 RAX: ffffffffffffffda RBX: 00000000004ce4e0 RCX: 00000000004455e9 RDX: 000000000000002e RSI: 00000000200000c0 RDI: 0000000000000003 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches