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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff8881005fc3f8 of 8 bytes by task 3313 on cpu 1:
 __filemap_add_folio+0x5b9/0x7d0 mm/filemap.c:919
 filemap_add_folio+0x1d9/0x360 mm/filemap.c:966
 __filemap_get_folio_mpol+0x326/0x650 mm/filemap.c:2016
 __filemap_get_folio include/linux/pagemap.h:763 [inline]
 grow_dev_folio fs/buffer.c:1050 [inline]
 grow_buffers fs/buffer.c:1116 [inline]
 __getblk_slow fs/buffer.c:1134 [inline]
 bdev_getblk+0x174/0x3f0 fs/buffer.c:1461
 getblk_unmovable include/linux/buffer_head.h:369 [inline]
 ext4_getblk+0x1b6/0x510 fs/ext4/inode.c:999
 ext4_bread+0x28/0x110 fs/ext4/inode.c:1047
 ext4_append+0x16e/0x2b0 fs/ext4/namei.c:83
 ext4_init_new_dir+0xec/0x180 fs/ext4/namei.c:2979
 ext4_mkdir+0x31f/0x740 fs/ext4/namei.c:3015
 vfs_mkdir+0x2db/0x3d0 fs/namei.c:5130
 do_mkdirat+0x133/0x3b0 fs/namei.c:5164
 __do_sys_mkdirat fs/namei.c:5186 [inline]
 __se_sys_mkdirat fs/namei.c:5184 [inline]
 __x64_sys_mkdirat+0x4c/0x60 fs/namei.c:5184
 x64_sys_call+0x30c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:259
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd8/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881005fc3f8 of 8 bytes by task 10 on cpu 0:
 nr_blockdev_pages+0x7e/0xd0 block/bdev.c:540
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 update_defense_level+0x47/0x5c0 net/netfilter/ipvs/ip_vs_ctl.c:101
 defense_work_handler+0x1f/0x80 net/netfilter/ipvs/ip_vs_ctl.c:234
 process_one_work kernel/workqueue.c:3257 [inline]
 process_scheduled_works+0x4ce/0x9d0 kernel/workqueue.c:3340
 worker_thread+0x582/0x770 kernel/workqueue.c:3421
 kthread+0x489/0x510 kernel/kthread.c:463
 ret_from_fork+0x149/0x290 arch/x86/kernel/process.c:158
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:246

value changed: 0x0000000000000201 -> 0x0000000000000202

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10 Comm: kworker/0:1 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_long defense_work_handler
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