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BUG: KCSAN: data-race in delete_from_page_cache_batch / nr_blockdev_pages

read-write to 0xffff888101e15d50 of 8 bytes by task 8457 on cpu 0:
 page_cache_delete_batch mm/filemap.c:340 [inline]
 delete_from_page_cache_batch+0x57b/0x800 mm/filemap.c:358
 truncate_inode_pages_range+0x482/0xf20 mm/truncate.c:366
 truncate_inode_pages+0x20/0x30 mm/truncate.c:476
 kill_bdev fs/block_dev.c:86 [inline]
 __blkdev_put+0x1f5/0x4a0 fs/block_dev.c:1776
 blkdev_put+0x1d9/0x200 fs/block_dev.c:1844
 kill_block_super+0x7b/0x90 fs/super.c:1449
 deactivate_locked_super+0x6a/0xb0 fs/super.c:335
 deactivate_super+0x85/0x90 fs/super.c:366
 cleanup_mnt+0x277/0x2e0 fs/namespace.c:1118
 __cleanup_mnt+0x15/0x20 fs/namespace.c:1125
 task_work_run+0x8e/0x110 kernel/task_work.c:151
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_user_mode_loop kernel/entry/common.c:164 [inline]
 exit_to_user_mode_prepare+0x13c/0x170 kernel/entry/common.c:191
 syscall_exit_to_user_mode+0x16/0x30 kernel/entry/common.c:266
 do_syscall_64+0x45/0x80 arch/x86/entry/common.c:56
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

read to 0xffff888101e15d50 of 8 bytes by task 14544 on cpu 1:
 nr_blockdev_pages+0x7c/0xd0 fs/block_dev.c:946
 si_meminfo+0x3a/0x60 mm/page_alloc.c:5335
 update_defense_level+0x34/0x550 net/netfilter/ipvs/ip_vs_ctl.c:101
 defense_work_handler+0x1b/0x80 net/netfilter/ipvs/ip_vs_ctl.c:235
 process_one_work+0x3e1/0x950 kernel/workqueue.c:2272
 worker_thread+0x635/0xb90 kernel/workqueue.c:2418
 kthread+0x1fd/0x220 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:296

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14544 Comm: kworker/1:6 Not tainted 5.10.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_long defense_work_handler
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