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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff8881006311f0 of 8 bytes by task 4125 on cpu 0:
 __filemap_add_folio+0x5b9/0x7d0 mm/filemap.c:928
 filemap_add_folio+0x98/0x1b0 mm/filemap.c:969
 __filemap_get_folio+0x31e/0x650 mm/filemap.c:1990
 grow_dev_folio fs/buffer.c:1050 [inline]
 grow_buffers fs/buffer.c:1116 [inline]
 __getblk_slow fs/buffer.c:1140 [inline]
 bdev_getblk+0x16e/0x3d0 fs/buffer.c:1467
 getblk_unmovable include/linux/buffer_head.h:371 [inline]
 ext4_getblk+0x1b6/0x510 fs/ext4/inode.c:975
 ext4_bread_batch+0x5c/0x320 fs/ext4/inode.c:1044
 __ext4_find_entry+0x840/0xf40 fs/ext4/namei.c:1601
 ext4_lookup_entry fs/ext4/namei.c:1703 [inline]
 ext4_lookup+0xbb/0x390 fs/ext4/namei.c:1771
 lookup_open fs/namei.c:3686 [inline]
 open_last_lookups fs/namei.c:3807 [inline]
 path_openat+0xcf3/0x2170 fs/namei.c:4043
 do_filp_open+0x109/0x230 fs/namei.c:4073
 do_sys_openat2+0xa6/0x110 fs/open.c:1437
 do_sys_open fs/open.c:1452 [inline]
 __do_sys_openat fs/open.c:1468 [inline]
 __se_sys_openat fs/open.c:1463 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1463
 x64_sys_call+0x1af/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:258
 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 0xffff8881006311f0 of 8 bytes by task 23 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:3238 [inline]
 process_scheduled_works+0x4cb/0x9d0 kernel/workqueue.c:3321
 worker_thread+0x582/0x770 kernel/workqueue.c:3402
 kthread+0x486/0x510 kernel/kthread.c:464
 ret_from_fork+0xda/0x150 arch/x86/kernel/process.c:148
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000000005 -> 0x0000000000000006

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 23 Comm: kworker/1:0 Not tainted 6.16.0-rc1-syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Workqueue: events_long defense_work_handler
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