Date:   Wed, 4 Jan 2023 11:39:13 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     syzbot <syzbot+f9db6ff27b9bfdcfeca0@...kaller.appspotmail.com>
Cc:     davem@...emloft.net, edumazet@...gle.com, kuba@...nel.org,
        linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
        mst@...hat.com, netdev@...r.kernel.org, pabeni@...hat.com,
        rds-devel@....oracle.com, santosh.shilimkar@...cle.com,
        syzkaller-bugs@...glegroups.com,
        virtualization@...ts.linux-foundation.org
Subject: Re: [syzbot] possible deadlock in rds_message_put

On Wed, Jan 4, 2023 at 8:19 AM syzbot
<syzbot+f9db6ff27b9bfdcfeca0@...kaller.appspotmail.com> wrote:
>
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    c183e6c3ec34 Merge git://git.kernel.org/pub/scm/linux/kern..
> git tree:       net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=1161aa7c480000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=8ca07260bb631fb4
> dashboard link: https://syzkaller.appspot.com/bug?extid=f9db6ff27b9bfdcfeca0
> 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=1370b478480000
> C reproducer:   https://syzkaller.appspot.com/x/repro.c?x=17ab141a480000
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/9b693820fb05/disk-c183e6c3.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/e449d80e60dc/vmlinux-c183e6c3.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/08e31763ce79/bzImage-c183e6c3.xz
>
> The issue was bisected to:
>
> commit 1628c6877f371194b603330c324828d03e0eacda
> Author: Jason Wang <jasowang@...hat.com>
> Date:   Mon Jan 4 06:55:02 2021 +0000
>
>     virtio_vdpa: don't warn when fail to disable vq
>

There's little chance for this commit to be the first bad one. It only
removes a WARN_ON().

Thanks

> bisection log:  https://syzkaller.appspot.com/x/bisect.txt?x=1479f7da480000
> final oops:     https://syzkaller.appspot.com/x/report.txt?x=1679f7da480000
> console output: https://syzkaller.appspot.com/x/log.txt?x=1279f7da480000
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+f9db6ff27b9bfdcfeca0@...kaller.appspotmail.com
> Fixes: 1628c6877f37 ("virtio_vdpa: don't warn when fail to disable vq")
>
> ======================================================
> WARNING: possible circular locking dependency detected
> 6.1.0-syzkaller-11778-gc183e6c3ec34 #0 Not tainted
> ------------------------------------------------------
> syz-executor390/18169 is trying to acquire lock:
> ffff8880763af100 (&rm->m_rs_lock){..-.}-{2:2}, at: rds_message_purge net/rds/message.c:138 [inline]
> ffff8880763af100 (&rm->m_rs_lock){..-.}-{2:2}, at: rds_message_put+0x1dd/0xc20 net/rds/message.c:180
>
> but task is already holding lock:
> ffff88802afafa70 (&rs->rs_recv_lock){...-}-{2:2}, at: rds_clear_recv_queue+0x33/0x350 net/rds/recv.c:761
>
> which lock already depends on the new lock.
>
>
> the existing dependency chain (in reverse order) is:
>
> -> #1 (&rs->rs_recv_lock){...-}-{2:2}:
>        __raw_read_lock_irqsave include/linux/rwlock_api_smp.h:160 [inline]
>        _raw_read_lock_irqsave+0x49/0x90 kernel/locking/spinlock.c:236
>        rds_wake_sk_sleep+0x23/0xe0 net/rds/af_rds.c:109
>        rds_send_remove_from_sock+0xb9/0x9e0 net/rds/send.c:634
>        rds_send_path_drop_acked+0x2f3/0x3d0 net/rds/send.c:710
>        rds_tcp_write_space+0x1b5/0x690 net/rds/tcp_send.c:198
>        tcp_new_space net/ipv4/tcp_input.c:5483 [inline]
>        tcp_check_space+0x11b/0x810 net/ipv4/tcp_input.c:5502
>        tcp_data_snd_check net/ipv4/tcp_input.c:5511 [inline]
>        tcp_rcv_established+0x93e/0x2230 net/ipv4/tcp_input.c:6019
>        tcp_v4_do_rcv+0x670/0x9b0 net/ipv4/tcp_ipv4.c:1721
>        sk_backlog_rcv include/net/sock.h:1113 [inline]
>        __release_sock+0x133/0x3b0 net/core/sock.c:2928
>        release_sock+0x58/0x1b0 net/core/sock.c:3485
>        rds_send_xmit+0xafc/0x2540 net/rds/send.c:422
>        rds_sendmsg+0x27d3/0x3080 net/rds/send.c:1381
>        sock_sendmsg_nosec net/socket.c:714 [inline]
>        sock_sendmsg+0xd3/0x120 net/socket.c:734
>        __sys_sendto+0x23a/0x340 net/socket.c:2117
>        __do_sys_sendto net/socket.c:2129 [inline]
>        __se_sys_sendto net/socket.c:2125 [inline]
>        __x64_sys_sendto+0xe1/0x1b0 net/socket.c:2125
>        do_syscall_x64 arch/x86/entry/common.c:50 [inline]
>        do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
>        entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> -> #0 (&rm->m_rs_lock){..-.}-{2:2}:
>        check_prev_add kernel/locking/lockdep.c:3097 [inline]
>        check_prevs_add kernel/locking/lockdep.c:3216 [inline]
>        validate_chain kernel/locking/lockdep.c:3831 [inline]
>        __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
>        lock_acquire kernel/locking/lockdep.c:5668 [inline]
>        lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
>        __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>        _raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
>        rds_message_purge net/rds/message.c:138 [inline]
>        rds_message_put+0x1dd/0xc20 net/rds/message.c:180
>        rds_inc_put net/rds/recv.c:82 [inline]
>        rds_inc_put+0x13e/0x1a0 net/rds/recv.c:76
>        rds_clear_recv_queue+0x14b/0x350 net/rds/recv.c:767
>        rds_release+0xd8/0x3c0 net/rds/af_rds.c:73
>        __sock_release+0xcd/0x280 net/socket.c:650
>        sock_close+0x1c/0x20 net/socket.c:1365
>        __fput+0x27c/0xa90 fs/file_table.c:320
>        task_work_run+0x16f/0x270 kernel/task_work.c:179
>        resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
>        exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
>        exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:203
>        __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
>        syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
>        do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
>        entry_SYSCALL_64_after_hwframe+0x63/0xcd
>
> other info that might help us debug this:
>
>  Possible unsafe locking scenario:
>
>        CPU0                    CPU1
>        ----                    ----
>   lock(&rs->rs_recv_lock);
>                                lock(&rm->m_rs_lock);
>                                lock(&rs->rs_recv_lock);
>   lock(&rm->m_rs_lock);
>
>  *** DEADLOCK ***
>
> 2 locks held by syz-executor390/18169:
>  #0: ffff8880719a3210 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: inode_lock include/linux/fs.h:756 [inline]
>  #0: ffff8880719a3210 (&sb->s_type->i_mutex_key#10){+.+.}-{3:3}, at: __sock_release+0x86/0x280 net/socket.c:649
>  #1: ffff88802afafa70 (&rs->rs_recv_lock){...-}-{2:2}, at: rds_clear_recv_queue+0x33/0x350 net/rds/recv.c:761
>
> stack backtrace:
> CPU: 0 PID: 18169 Comm: syz-executor390 Not tainted 6.1.0-syzkaller-11778-gc183e6c3ec34 #0
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
> Call Trace:
>  <TASK>
>  __dump_stack lib/dump_stack.c:88 [inline]
>  dump_stack_lvl+0xd1/0x138 lib/dump_stack.c:106
>  check_noncircular+0x25f/0x2e0 kernel/locking/lockdep.c:2177
>  check_prev_add kernel/locking/lockdep.c:3097 [inline]
>  check_prevs_add kernel/locking/lockdep.c:3216 [inline]
>  validate_chain kernel/locking/lockdep.c:3831 [inline]
>  __lock_acquire+0x2a43/0x56d0 kernel/locking/lockdep.c:5055
>  lock_acquire kernel/locking/lockdep.c:5668 [inline]
>  lock_acquire+0x1e3/0x630 kernel/locking/lockdep.c:5633
>  __raw_spin_lock_irqsave include/linux/spinlock_api_smp.h:110 [inline]
>  _raw_spin_lock_irqsave+0x3d/0x60 kernel/locking/spinlock.c:162
>  rds_message_purge net/rds/message.c:138 [inline]
>  rds_message_put+0x1dd/0xc20 net/rds/message.c:180
>  rds_inc_put net/rds/recv.c:82 [inline]
>  rds_inc_put+0x13e/0x1a0 net/rds/recv.c:76
>  rds_clear_recv_queue+0x14b/0x350 net/rds/recv.c:767
>  rds_release+0xd8/0x3c0 net/rds/af_rds.c:73
>  __sock_release+0xcd/0x280 net/socket.c:650
>  sock_close+0x1c/0x20 net/socket.c:1365
>  __fput+0x27c/0xa90 fs/file_table.c:320
>  task_work_run+0x16f/0x270 kernel/task_work.c:179
>  resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
>  exit_to_user_mode_loop kernel/entry/common.c:171 [inline]
>  exit_to_user_mode_prepare+0x23c/0x250 kernel/entry/common.c:203
>  __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
>  syscall_exit_to_user_mode+0x1d/0x50 kernel/entry/common.c:296
>  do_syscall_64+0x46/0xb0 arch/x86/entry/common.c:86
>  entry_SYSCALL_64_after_hwframe+0x63/0xcd
> RIP: 0033:0x7f4a3a75f5fb
> Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 03 fd ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 41 fd ff ff 8b 44
> RSP: 002b:00007ffff26fde60 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
> RAX: 0000000000000000 RBX: 0000000000000005 RCX: 00007f4a3a75f5fb
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
> RBP: 0000000000000032 R08: 0000000000000000 R09: 00007f4a3a7f51ae
> R10: 0000000000000000 R11: 0000000000000293 R12: 00007f4a3a8284ec
> R13: 00007ffff26fdeb0 R14: 00007ffff26fded0 R15: 00007ffff26fdf40
>  </TASK>
>
>
> ---
> 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@...glegroups.com.
>
> syzbot will keep track of this issue. See:
> https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
> For information about bisection process see: https://goo.gl/tpsmEJ#bisection
> syzbot can test patches for this issue, for details see:
> https://goo.gl/tpsmEJ#testing-patches
>

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