syzbot

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BUG: KCSAN: data-race in do_sys_poll / pollwake

write to 0xffffc90000ecbbd0 of 4 bytes by task 3045 on cpu 1:
 __pollwake fs/select.c:195 [inline]
 pollwake+0xb6/0x100 fs/select.c:215
 __wake_up_common kernel/sched/wait.c:89 [inline]
 __wake_up_common_lock kernel/sched/wait.c:106 [inline]
 __wake_up_sync_key+0x4f/0x80 kernel/sched/wait.c:173
 sock_def_readable+0x70/0x190 net/core/sock.c:3533
 unix_dgram_sendmsg+0x99d/0xec0 net/unix/af_unix.c:2154
 unix_seqpacket_sendmsg+0xd1/0x110 net/unix/af_unix.c:2375
 sock_sendmsg_nosec net/socket.c:712 [inline]
 __sock_sendmsg+0x142/0x180 net/socket.c:727
 sock_write_iter+0x165/0x1b0 net/socket.c:1131
 do_iter_readv_writev+0x41e/0x4c0 fs/read_write.c:-1
 vfs_writev+0x2c9/0x870 fs/read_write.c:1055
 do_writev+0xe7/0x210 fs/read_write.c:1101
 __do_sys_writev fs/read_write.c:1169 [inline]
 __se_sys_writev fs/read_write.c:1166 [inline]
 __x64_sys_writev+0x45/0x50 fs/read_write.c:1166
 x64_sys_call+0x2006/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:21
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffc90000ecbbd0 of 4 bytes by task 3046 on cpu 0:
 poll_schedule_timeout fs/select.c:240 [inline]
 do_poll fs/select.c:958 [inline]
 do_sys_poll+0x97b/0xbc0 fs/select.c:1009
 __do_sys_ppoll fs/select.c:1115 [inline]
 __se_sys_ppoll+0x1b9/0x200 fs/select.c:1095
 __x64_sys_ppoll+0x67/0x80 fs/select.c:1095
 x64_sys_call+0x2de5/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:272
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd0/0x1a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3046 Comm: dhcpcd Not tainted 6.15.0-rc5-syzkaller-00275-gbec6f00f120e #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/19/2025
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