==================================================================
BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff888100483db8 of 8 bytes by task 28264 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 include/linux/buffer_head.h:380 [inline]
 sb_getblk include/linux/buffer_head.h:386 [inline]
 read_mmp_block+0xa4/0x2b0 fs/ext4/mmp.c:85
 ext4_multi_mount_protect+0x112/0x600 fs/ext4/mmp.c:293
 __ext4_fill_super fs/ext4/super.c:5454 [inline]
 ext4_fill_super+0x22cf/0x37a0 fs/ext4/super.c:5777
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1691
 get_tree_bdev+0x1f/0x30 fs/super.c:1714
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5809
 vfs_get_tree+0x57/0x1d0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x24d/0x6a0 fs/namespace.c:3712
 path_mount+0x4ab/0xb80 fs/namespace.c:4022
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4201
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4201
 x64_sys_call+0x2cca/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 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 0xffff888100483db8 of 8 bytes by task 14699 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: 0x0000000000000001 -> 0x0000000000000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 14699 Comm: kworker/0:11 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
Workqueue: events_long defense_work_handler
==================================================================