syzbot

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BUG: KCSAN: data-race in __fsnotify_parent / select_collect

write to 0xffff888105fc9e40 of 4 bytes by task 1027 on cpu 1:
 d_lru_del fs/dcache.c:410 [inline]
 select_collect+0xaf/0x2b0 fs/dcache.c:1538
 d_walk+0x2d5/0x5d0 fs/dcache.c:1359
 shrink_dcache_parent+0x85/0x420 fs/dcache.c:1598
 d_invalidate+0x8a/0x1d0 fs/dcache.c:1710
 proc_invalidate_siblings_dcache+0x203/0x2f0 fs/proc/inode.c:150
 proc_flush_pid+0x16/0x20 fs/proc/base.c:3325
 release_task+0xad7/0xbe0 kernel/exit.c:222
 wait_task_zombie kernel/exit.c:1107 [inline]
 wait_consider_task+0x10ce/0x19e0 kernel/exit.c:1334
 do_wait_thread kernel/exit.c:1397 [inline]
 do_wait+0x1b1/0x4a0 kernel/exit.c:1468
 kernel_wait4+0x13c/0x1a0 kernel/exit.c:1630
 __do_sys_wait4 kernel/exit.c:1658 [inline]
 __se_sys_wait4 kernel/exit.c:1654 [inline]
 __x64_sys_wait4+0x7a/0x100 kernel/exit.c:1654
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888105fc9e40 of 4 bytes by task 1021 on cpu 0:
 __fsnotify_parent+0x7d/0x430 fs/notify/fsnotify.c:187
 fsnotify_parent include/linux/fsnotify.h:68 [inline]
 fsnotify_file include/linux/fsnotify.h:90 [inline]
 fsnotify_access include/linux/fsnotify.h:247 [inline]
 vfs_read+0x35f/0x5d0 fs/read_write.c:500
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 1021 Comm: systemd-journal Not tainted 5.12.0-rc8-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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