syzbot

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BUG: KCSAN: data-race in fasync_remove_entry / sock_wake_async

write to 0xffff88811ed7a6d8 of 8 bytes by task 22824 on cpu 0:
 fasync_remove_entry+0xd5/0x140 fs/fcntl.c:884
 fasync_helper+0x92/0xc0 fs/fcntl.c:983
 sock_fasync+0x5c/0xc0 net/socket.c:1303
 __fput+0x420/0x460 fs/file_table.c:278
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:216 [inline]
 __prepare_exit_to_usermode+0x1c6/0x230 arch/x86/entry/common.c:246
 __syscall_return_slowpath+0x47/0x60 arch/x86/entry/common.c:329
 do_syscall_64+0x5d/0xb0 arch/x86/entry/common.c:368
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811ed7a6d8 of 8 bytes by task 22819 on cpu 1:
 sock_wake_async+0x26/0x100 net/socket.c:1318
 sk_wake_async include/net/sock.h:2260 [inline]
 unix_write_space+0x128/0x140 net/unix/af_unix.c:466
 sock_wfree+0xac/0x150 net/core/sock.c:2060
 unix_destruct_scm+0x164/0x190 net/unix/scm.c:149
 skb_release_head_state+0xb3/0x170 net/core/skbuff.c:651
 skb_release_all net/core/skbuff.c:662 [inline]
 __kfree_skb+0x14/0x150 net/core/skbuff.c:678
 kfree_skb+0x53/0x190 net/core/skbuff.c:696
 unix_release_sock+0x505/0x650 net/unix/af_unix.c:568
 unix_release+0x2f/0x50 net/unix/af_unix.c:867
 __sock_release net/socket.c:605 [inline]
 sock_close+0x6c/0x150 net/socket.c:1278
 __fput+0x1df/0x460 fs/file_table.c:281
 ____fput+0x11/0x20 fs/file_table.c:314
 task_work_run+0x8e/0x110 kernel/task_work.c:123
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop arch/x86/entry/common.c:216 [inline]
 __prepare_exit_to_usermode+0x1c6/0x230 arch/x86/entry/common.c:246
 __syscall_return_slowpath+0x47/0x60 arch/x86/entry/common.c:329
 do_syscall_64+0x5d/0xb0 arch/x86/entry/common.c:368
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22819 Comm: syz-executor.3 Not tainted 5.8.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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