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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff8881006311f8 of 8 bytes by task 13569 on cpu 0:
 __filemap_add_folio+0x439/0x710 mm/filemap.c:918
 filemap_add_folio+0x9c/0x1b0 mm/filemap.c:970
 page_cache_ra_unbounded+0x148/0x2e0 mm/readahead.c:252
 do_page_cache_ra mm/readahead.c:303 [inline]
 page_cache_ra_order mm/readahead.c:547 [inline]
 ondemand_readahead+0x542/0x6b0 mm/readahead.c:669
 page_cache_async_ra+0x94/0xa0 mm/readahead.c:718
 filemap_readahead mm/filemap.c:2504 [inline]
 filemap_get_pages+0x398/0xfb0 mm/filemap.c:2545
 filemap_splice_read+0x360/0x920 mm/filemap.c:2894
 do_splice_read fs/splice.c:985 [inline]
 splice_direct_to_actor+0x26c/0x670 fs/splice.c:1089
 do_splice_direct_actor fs/splice.c:1207 [inline]
 do_splice_direct+0xd7/0x150 fs/splice.c:1233
 do_sendfile+0x3ab/0x960 fs/read_write.c:1295
 __do_sys_sendfile64 fs/read_write.c:1362 [inline]
 __se_sys_sendfile64 fs/read_write.c:1348 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1348
 x64_sys_call+0x2c9f/0x2d70 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881006311f8 of 8 bytes by task 970 on cpu 1:
 nr_blockdev_pages+0x7c/0xd0 block/bdev.c:475
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 update_defense_level+0x49/0x5b0 net/netfilter/ipvs/ip_vs_ctl.c:102
 defense_work_handler+0x1f/0x80 net/netfilter/ipvs/ip_vs_ctl.c:235
 process_one_work kernel/workqueue.c:3231 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3312
 worker_thread+0x526/0x730 kernel/workqueue.c:3393
 kthread+0x1d1/0x210 kernel/kthread.c:389
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244

value changed: 0x00000000000004c9 -> 0x00000000000004d2

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 970 Comm: kworker/1:2 Tainted: G        W          6.10.0-rc1-syzkaller-00104-gd8ec19857b09 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/02/2024
Workqueue: events_long defense_work_handler
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