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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff888100631e70 of 8 bytes by task 3116 on cpu 0:
 __filemap_add_folio+0x4c1/0x730 mm/filemap.c:902
 filemap_add_folio+0x70/0x160 mm/filemap.c:937
 __filemap_get_folio+0x2f1/0x5a0 mm/filemap.c:1926
 grow_dev_page fs/buffer.c:1041 [inline]
 grow_buffers fs/buffer.c:1106 [inline]
 __getblk_slow fs/buffer.c:1133 [inline]
 bdev_getblk+0x1bb/0x7a0 fs/buffer.c:1429
 __getblk include/linux/buffer_head.h:358 [inline]
 sb_getblk include/linux/buffer_head.h:364 [inline]
 ext4_getblk+0x1c1/0x510 fs/ext4/inode.c:841
 ext4_bread+0x2c/0x110 fs/ext4/inode.c:887
 ext4_append+0x164/0x2a0 fs/ext4/namei.c:83
 ext4_init_new_dir+0x17b/0x510 fs/ext4/namei.c:2980
 ext4_mkdir+0x312/0x740 fs/ext4/namei.c:3026
 vfs_mkdir+0x1ef/0x2f0 fs/namei.c:4106
 do_mkdirat+0x12f/0x2a0 fs/namei.c:4129
 __do_sys_mkdirat fs/namei.c:4144 [inline]
 __se_sys_mkdirat fs/namei.c:4142 [inline]
 __x64_sys_mkdirat+0x50/0x60 fs/namei.c:4142
 do_syscall_x64 arch/x86/entry/common.c:51 [inline]
 do_syscall_64+0x44/0x110 arch/x86/entry/common.c:82
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff888100631e70 of 8 bytes by task 19074 on cpu 1:
 nr_blockdev_pages+0x7c/0xd0 block/bdev.c:441
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 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:242

value changed: 0x000000000000065f -> 0x0000000000000660

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 19074 Comm: kworker/1:14 Not tainted 6.7.0-rc1-syzkaller-00125-g7475e51b8796 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/10/2023
Workqueue: events_long defense_work_handler
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