syzbot

BUG: KCSAN: data-race in __fsnotify_parent / select_collect

write to 0xffff8880b29d4780 of 4 bytes by task 8298 on cpu 0:
 d_lru_del fs/dcache.c:410 [inline]
 select_collect+0xaf/0x2b0 fs/dcache.c:1505
 d_walk+0x285/0x4d0 fs/dcache.c:1326
 shrink_dcache_parent+0x85/0x3f0 fs/dcache.c:1565
 d_invalidate+0x6e/0x1a0 fs/dcache.c:1677
 proc_invalidate_siblings_dcache+0x1e3/0x2d0 fs/proc/inode.c:150
 proc_flush_pid+0x16/0x20 fs/proc/base.c:3318
 release_task+0xa9f/0xb90 kernel/exit.c:221
 wait_task_zombie kernel/exit.c:1088 [inline]
 wait_consider_task+0x104f/0x18c0 kernel/exit.c:1315
 do_wait_thread kernel/exit.c:1378 [inline]
 do_wait+0x1b1/0x4d0 kernel/exit.c:1449
 kernel_wait4+0x13c/0x1a0 kernel/exit.c:1621
 __do_sys_wait4 kernel/exit.c:1649 [inline]
 __se_sys_wait4 kernel/exit.c:1645 [inline]
 __x64_sys_wait4+0x7a/0x100 kernel/exit.c:1645
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff8880b29d4780 of 4 bytes by task 5059 on cpu 1:
 __fsnotify_parent+0x79/0x470 fs/notify/fsnotify.c:180
 fsnotify_parent include/linux/fsnotify.h:68 [inline]
 fsnotify_file include/linux/fsnotify.h:90 [inline]
 fsnotify_perm+0x292/0x2d0 include/linux/fsnotify.h:115
 security_file_permission+0x87/0xa0 security/security.c:1450
 rw_verify_area+0x12c/0x240 fs/read_write.c:400
 vfs_read+0xf6/0x5e0 fs/read_write.c:472
 ksys_read+0xce/0x180 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read fs/read_write.c:615 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:615
 do_syscall_64+0x39/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 5059 Comm: systemd-journal Not tainted 5.9.0-rc3-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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