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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff888100631830 of 8 bytes by task 3667 on cpu 1:
 __filemap_add_folio+0x430/0x6f0 mm/filemap.c:920
 filemap_add_folio+0x9c/0x1b0 mm/filemap.c:972
 page_cache_ra_unbounded+0x175/0x310 mm/readahead.c:268
 do_page_cache_ra mm/readahead.c:320 [inline]
 force_page_cache_ra mm/readahead.c:349 [inline]
 page_cache_sync_ra+0x252/0x670 mm/readahead.c:562
 page_cache_sync_readahead include/linux/pagemap.h:1394 [inline]
 filemap_get_pages+0x2c1/0x10e0 mm/filemap.c:2547
 filemap_read+0x216/0x680 mm/filemap.c:2645
 blkdev_read_iter+0x20e/0x2c0 block/fops.c:765
 new_sync_read fs/read_write.c:488 [inline]
 vfs_read+0x5dc/0x700 fs/read_write.c:569
 ksys_read+0xeb/0x1b0 fs/read_write.c:712
 __do_sys_read fs/read_write.c:722 [inline]
 __se_sys_read fs/read_write.c:720 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:720
 x64_sys_call+0x27d3/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:1
 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 0xffff888100631830 of 8 bytes by task 9 on cpu 0:
 nr_blockdev_pages+0x7c/0xd0 block/bdev.c:482
 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:3229 [inline]
 process_scheduled_works+0x483/0x9a0 kernel/workqueue.c:3310
 worker_thread+0x51d/0x6f0 kernel/workqueue.c:3391
 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: 0x0000000000000001 -> 0x0000000000000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 9 Comm: kworker/0:1 Not tainted 6.12.0-rc7-syzkaller-00125-gcfaaa7d010d1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
Workqueue: events_long defense_work_handler
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