syzbot

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BUG: KCSAN: data-race in d_shrink_del / fsnotify_parent

write to 0xffff88811d483000 of 4 bytes by task 26333 on cpu 0:
 d_shrink_del+0xcd/0x170 fs/dcache.c:421
 shrink_dentry_list+0x128/0x1d0 fs/dcache.c:1109
 shrink_dcache_sb+0x106/0x1c0 fs/dcache.c:1242
 reconfigure_super+0x318/0x570 fs/super.c:940
 do_remount fs/namespace.c:2553 [inline]
 do_mount+0x1120/0x1590 fs/namespace.c:3132
 __do_sys_mount fs/namespace.c:3350 [inline]
 __se_sys_mount fs/namespace.c:3327 [inline]
 __x64_sys_mount+0x12b/0x1a0 fs/namespace.c:3327
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff88811d483000 of 4 bytes by task 26329 on cpu 1:
 fsnotify_parent+0x4d/0x1b0 fs/notify/fsnotify.c:153
 fsnotify_file include/linux/fsnotify.h:74 [inline]
 fsnotify_perm include/linux/fsnotify.h:103 [inline]
 fsnotify_perm include/linux/fsnotify.h:82 [inline]
 security_file_permission+0x1a1/0x300 security/security.c:1430
 rw_verify_area+0xd8/0x230 fs/read_write.c:400
 do_splice_to+0x5f/0x100 fs/splice.c:880
 splice_direct_to_actor+0x1b9/0x540 fs/splice.c:971
 do_splice_direct+0x152/0x1d0 fs/splice.c:1080
 do_sendfile+0x380/0x800 fs/read_write.c:1521
 __do_sys_sendfile64 fs/read_write.c:1582 [inline]
 __se_sys_sendfile64 fs/read_write.c:1568 [inline]
 __x64_sys_sendfile64+0x121/0x140 fs/read_write.c:1568
 do_syscall_64+0xc7/0x3b0 arch/x86/entry/common.c:295
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26329 Comm: syz-executor.5 Not tainted 5.7.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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