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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff8881004c0bb0 of 8 bytes by task 20041 on cpu 0:
 __filemap_add_folio+0x432/0x710 mm/filemap.c:929
 filemap_add_folio+0x9f/0x1b0 mm/filemap.c:981
 __filemap_get_folio+0x340/0x6b0 mm/filemap.c:1991
 grow_dev_folio fs/buffer.c:1039 [inline]
 grow_buffers fs/buffer.c:1105 [inline]
 __getblk_slow fs/buffer.c:1131 [inline]
 bdev_getblk+0x173/0x3b0 fs/buffer.c:1431
 __bread_gfp+0x52/0x280 fs/buffer.c:1485
 sb_bread include/linux/buffer_head.h:345 [inline]
 fat__get_entry fs/fat/dir.c:100 [inline]
 fat_get_entry+0x486/0x5f0 fs/fat/dir.c:128
 fat_get_short_entry fs/fat/dir.c:885 [inline]
 fat_subdirs+0xfc/0x1a0 fs/fat/dir.c:951
 fat_read_root+0x317/0x360 fs/fat/inode.c:1345
 fat_fill_super+0x1548/0x1c70 fs/fat/inode.c:1814
 vfat_fill_super+0x24/0x30 fs/fat/namei_vfat.c:1197
 get_tree_bdev_flags+0x2b4/0x330 fs/super.c:1636
 get_tree_bdev+0x1f/0x30 fs/super.c:1659
 vfat_get_tree+0x1c/0x30 fs/fat/namei_vfat.c:1202
 vfs_get_tree+0x56/0x1e0 fs/super.c:1759
 do_new_mount+0x246/0x6b0 fs/namespace.c:3878
 path_mount+0x49b/0xb30 fs/namespace.c:4205
 do_mount fs/namespace.c:4218 [inline]
 __do_sys_mount fs/namespace.c:4429 [inline]
 __se_sys_mount+0x28f/0x2e0 fs/namespace.c:4406
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4406
 x64_sys_call+0xd11/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881004c0bb0 of 8 bytes by task 36 on cpu 1:
 nr_blockdev_pages+0x7c/0xd0 block/bdev.c:485
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 update_defense_level+0x4b/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+0x4de/0xa20 kernel/workqueue.c:3319
 worker_thread+0x52c/0x710 kernel/workqueue.c:3400
 kthread+0x4b7/0x540 kernel/kthread.c:464
 ret_from_fork+0x4b/0x60 arch/x86/kernel/process.c:153
 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245

value changed: 0x0000000000000027 -> 0x000000000000002c

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 36 Comm: kworker/1:1 Tainted: G        W          6.14.0-syzkaller-09584-g7d06015d936c #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
Workqueue: events_long defense_work_handler
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