[net?] [s390?] KCSAN: data-race in smc_poll / smc_switch_to_fallback

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1fe4fd6f5cad Merge tag 'xfs-6.2-fixes-2' of git://git.kern..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=12ebb6f6480000
kernel config: https://syzkaller.appspot.com/x/.config?x=64543f00d69a19cc
dashboard link: https://syzkaller.appspot.com/bug?extid=3b3f756e24586e8619c9
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
CC: [da...@davemloft.net edum...@google.com ja...@linux.ibm.com kgr...@linux.ibm.com ku...@kernel.org linux-...@vger.kernel.org linux...@vger.kernel.org net...@vger.kernel.org pab...@redhat.com wen...@linux.ibm.com]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/65e368f3968e/disk-1fe4fd6f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c26eb5e0db6d/vmlinux-1fe4fd6f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/3aa7fccecc9e/bzImage-1fe4fd6f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+3b3f75...@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in smc_poll / smc_switch_to_fallback

write to 0xffff8881321b9d3d of 1 bytes by task 9321 on cpu 0:
smc_switch_to_fallback+0x5f/0x730 net/smc/af_smc.c:872
smc_sendmsg+0x191/0x380 net/smc/af_smc.c:2656
sock_sendmsg_nosec net/socket.c:714 [inline]
sock_sendmsg net/socket.c:734 [inline]
____sys_sendmsg+0x38f/0x500 net/socket.c:2476
___sys_sendmsg net/socket.c:2530 [inline]
__sys_sendmsg+0x19a/0x230 net/socket.c:2559
__do_sys_sendmsg net/socket.c:2568 [inline]
__se_sys_sendmsg net/socket.c:2566 [inline]
__x64_sys_sendmsg+0x42/0x50 net/socket.c:2566
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881321b9d3d of 1 bytes by task 9320 on cpu 1:
smc_poll+0x41/0x4a0 net/smc/af_smc.c:2737
sock_poll+0x23e/0x260 net/socket.c:1353
vfs_poll include/linux/poll.h:88 [inline]
do_pollfd fs/select.c:873 [inline]
do_poll fs/select.c:921 [inline]
do_sys_poll+0x6d5/0xca0 fs/select.c:1015
__do_sys_ppoll fs/select.c:1121 [inline]
__se_sys_ppoll+0x195/0x1d0 fs/select.c:1101
__x64_sys_ppoll+0x63/0x70 fs/select.c:1101
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9320 Comm: syz-executor.4 Tainted: G W 6.2.0-rc3-syzkaller-00008-g1fe4fd6f5cad-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
==================================================================


---
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 syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.

[syzbot]

Auto-closing this bug as obsolete.
Crashes did not happen for a while, no reproducer and no activity.