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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff8881005b24b0 of 8 bytes by task 27505 on cpu 1:
 __filemap_add_folio+0x3c3/0x750 mm/filemap.c:904
 filemap_add_folio+0x70/0x160 mm/filemap.c:939
 __filemap_get_folio+0x31f/0x500 mm/filemap.c:1944
 iomap_get_folio fs/iomap/buffered-io.c:554 [inline]
 __iomap_get_folio fs/iomap/buffered-io.c:701 [inline]
 iomap_write_begin+0x26f/0xe90 fs/iomap/buffered-io.c:744
 iomap_write_iter fs/iomap/buffered-io.c:909 [inline]
 iomap_file_buffered_write+0x231/0x570 fs/iomap/buffered-io.c:970
 blkdev_buffered_write block/fops.c:634 [inline]
 blkdev_write_iter+0x2c1/0x390 block/fops.c:684
 do_iter_write+0x4b4/0x7b0 fs/read_write.c:860
 vfs_iter_write+0x56/0x70 fs/read_write.c:901
 iter_file_splice_write+0x462/0x7e0 fs/splice.c:736
 do_splice_from fs/splice.c:933 [inline]
 direct_splice_actor+0x8a/0xb0 fs/splice.c:1142
 splice_direct_to_actor+0x31d/0x690 fs/splice.c:1088
 do_splice_direct+0x10d/0x190 fs/splice.c:1194
 do_sendfile+0x3b6/0x9a0 fs/read_write.c:1254
 __do_sys_sendfile64 fs/read_write.c:1322 [inline]
 __se_sys_sendfile64 fs/read_write.c:1308 [inline]
 __x64_sys_sendfile64+0x110/0x150 fs/read_write.c:1308
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff8881005b24b0 of 8 bytes by task 28555 on cpu 0:
 nr_blockdev_pages+0x7c/0xd0 block/bdev.c:441
 si_meminfo+0x87/0xd0 mm/show_mem.c:83
 update_defense_level+0x46/0x600 net/netfilter/ipvs/ip_vs_ctl.c:101
 defense_work_handler+0x1f/0x80 net/netfilter/ipvs/ip_vs_ctl.c:235
 process_one_work kernel/workqueue.c:2630 [inline]
 process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
 worker_thread+0x525/0x730 kernel/workqueue.c:2784
 kthread+0x1d7/0x210 kernel/kthread.c:388
 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x000000000000003b -> 0x000000000000003c

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 28555 Comm: kworker/0:2 Not tainted 6.6.0-rc5-syzkaller-00234-g8cb1f10d8c4b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: events_long defense_work_handler
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