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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

write to 0xffff888101356c78 of 8 bytes by task 16568 on cpu 1:
 __filemap_add_folio+0x256/0x4d0 mm/filemap.c:946
 filemap_add_folio+0x6b/0x150 mm/filemap.c:999
 add_to_page_cache_lru+0x4e/0x70 mm/folio-compat.c:115
 page_cache_ra_unbounded+0x274/0x430 mm/readahead.c:221
 do_page_cache_ra mm/readahead.c:268 [inline]
 force_page_cache_ra+0x1e6/0x220 mm/readahead.c:300
 page_cache_sync_ra+0xcc/0xe0 mm/readahead.c:574
 page_cache_sync_readahead include/linux/pagemap.h:1029 [inline]
 filemap_get_pages mm/filemap.c:2556 [inline]
 filemap_read+0x3eb/0x16d0 mm/filemap.c:2642
 generic_file_read_iter+0x72/0x2a0 mm/filemap.c:2792
 blkdev_read_iter+0x96/0x140 block/fops.c:583
 call_read_iter include/linux/fs.h:2156 [inline]
 new_sync_read fs/read_write.c:400 [inline]
 vfs_read+0x66c/0x750 fs/read_write.c:481
 ksys_read+0xd9/0x190 fs/read_write.c:619
 __do_sys_read fs/read_write.c:629 [inline]
 __se_sys_read fs/read_write.c:627 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:627
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888101356c78 of 8 bytes by task 17298 on cpu 0:
 nr_blockdev_pages+0x7f/0xd0 block/bdev.c:522
 si_meminfo+0x3a/0x60 mm/page_alloc.c:5778
 update_defense_level+0x46/0x560 net/netfilter/ipvs/ip_vs_ctl.c:102
 defense_work_handler+0x1b/0x80 net/netfilter/ipvs/ip_vs_ctl.c:236
 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298
 worker_thread+0x616/0xa70 kernel/workqueue.c:2445
 kthread+0x2c7/0x2e0 kernel/kthread.c:327
 ret_from_fork+0x1f/0x30

value changed: 0x0000000000000001 -> 0x0000000000000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 17298 Comm: kworker/0:13 Tainted: G        W         5.16.0-rc4-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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