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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff888100480bb8 of 8 bytes by task 3510 on cpu 0:
 __filemap_add_folio+0x5b9/0x7d0 mm/filemap.c:931
 filemap_add_folio+0x1d9/0x360 mm/filemap.c:978
 page_cache_ra_unbounded+0x203/0x450 mm/readahead.c:280
 do_page_cache_ra mm/readahead.c:332 [inline]
 force_page_cache_ra mm/readahead.c:361 [inline]
 page_cache_sync_ra+0x26e/0x6a0 mm/readahead.c:579
 filemap_get_pages+0x2d0/0x11b0 mm/filemap.c:2638
 filemap_read+0x231/0xa00 mm/filemap.c:2748
 blkdev_read_iter+0x22d/0x2e0 block/fops.c:859
 new_sync_read fs/read_write.c:491 [inline]
 vfs_read+0x64c/0x770 fs/read_write.c:572
 ksys_read+0xda/0x1a0 fs/read_write.c:715
 __do_sys_read fs/read_write.c:724 [inline]
 __se_sys_read fs/read_write.c:722 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:722
 x64_sys_call+0x27c0/0x3000 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff888100480bb8 of 8 bytes by task 3422 on cpu 1:
 nr_blockdev_pages+0x7e/0xd0 block/bdev.c:523
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 update_defense_level+0x47/0x5c0 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:3263 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3346
 worker_thread+0x582/0x770 kernel/workqueue.c:3427
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x122/0x1b0 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000000009 -> 0x000000000000000a

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 3422 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
Workqueue: events_long defense_work_handler
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