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BUG: KCSAN: data-race in smc_poll / smc_switch_to_fallback

write to 0xffff88810a188e4d of 1 bytes by task 19015 on cpu 0:
 smc_switch_to_fallback+0x5a/0x7f0 net/smc/af_smc.c:927
 smc_sendmsg+0xce/0x2f0 net/smc/af_smc.c:2797
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg net/socket.c:742 [inline]
 ____sys_sendmsg+0x5af/0x600 net/socket.c:2592
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681
 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff88810a188e4d of 1 bytes by task 19013 on cpu 1:
 smc_poll+0x275/0x530 net/smc/af_smc.c:2898
 sock_poll+0x21c/0x240 net/socket.c:1443
 vfs_poll include/linux/poll.h:82 [inline]
 __io_arm_poll_handler+0x1ec/0xc30 io_uring/poll.c:581
 io_poll_add+0x69/0xf0 io_uring/poll.c:899
 __io_issue_sqe+0xfd/0x2d0 io_uring/io_uring.c:1384
 io_issue_sqe+0x206/0xc00 io_uring/io_uring.c:1407
 io_queue_sqe io_uring/io_uring.c:1634 [inline]
 io_submit_sqe io_uring/io_uring.c:1920 [inline]
 io_submit_sqes+0x7fb/0x1270 io_uring/io_uring.c:2043
 __do_sys_io_uring_enter io_uring/io_uring.c:2603 [inline]
 __se_sys_io_uring_enter+0x1c9/0xf50 io_uring/io_uring.c:2538
 __x64_sys_io_uring_enter+0x78/0x90 io_uring/io_uring.c:2538
 x64_sys_call+0x1e16/0x3020 arch/x86/include/generated/asm/syscalls_64.h:427
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x12c/0x370 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00 -> 0x01

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 19013 Comm: syz.7.4546 Tainted: G        W           syzkaller #0 PREEMPT(full) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
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