[syzbot] [rds?] KCSAN: data-race in rds_sendmsg / rds_sendmsg

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit:    401644852d0b Merge tag 'fs_for_v6.6-rc6' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=10bbf9ce680000
kernel config:  https://syzkaller.appspot.com/x/.config?x=70d8e328e7a4e377
dashboard link: https://syzkaller.appspot.com/bug?extid=00563755980a79a575f6
compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/32193fa290fa/disk-40164485.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/45596bbf452b/vmlinux-40164485.xz
kernel image: https://storage.googleapis.com/syzbot-assets/930999dd8dfc/bzImage-40164485.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+00563755980a79a575f6@xxxxxxxxxxxxxxxxxxxxxxxxx

==================================================================
BUG: KCSAN: data-race in rds_sendmsg / rds_sendmsg

write to 0xffff8881039110f8 of 8 bytes by task 15969 on cpu 0:
 rds_sendmsg+0xbc6/0x1410 net/rds/send.c:1304
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2558
 ___sys_sendmsg net/socket.c:2612 [inline]
 __sys_sendmsg+0x1e9/0x270 net/socket.c:2641
 __do_sys_sendmsg net/socket.c:2650 [inline]
 __se_sys_sendmsg net/socket.c:2648 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881039110f8 of 8 bytes by task 15973 on cpu 1:
 rds_sendmsg+0xa51/0x1410 net/rds/send.c:1291
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2558
 ___sys_sendmsg net/socket.c:2612 [inline]
 __sys_sendmsg+0x1e9/0x270 net/socket.c:2641
 __do_sys_sendmsg net/socket.c:2650 [inline]
 __se_sys_sendmsg net/socket.c:2648 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2648
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000000000000 -> 0xffff888137df17e8

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 15973 Comm: syz-executor.0 Not tainted 6.6.0-rc5-syzkaller-00072-g401644852d0b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
==================================================================


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