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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff8881005f0bb8 of 8 bytes by task 12571 on cpu 1:
 __filemap_add_folio+0x5b9/0x7d0 mm/filemap.c:931
 filemap_add_folio+0x1d9/0x360 mm/filemap.c:978
 __filemap_get_folio+0x31e/0x650 mm/filemap.c:2022
 grow_dev_folio fs/buffer.c:1050 [inline]
 grow_buffers fs/buffer.c:1116 [inline]
 __getblk_slow fs/buffer.c:1134 [inline]
 bdev_getblk+0x14d/0x3b0 fs/buffer.c:1461
 __breadahead+0x29/0x170 fs/buffer.c:1470
 sb_breadahead include/linux/buffer_head.h:358 [inline]
 fat_ent_reada+0x1b7/0x2c0 fs/fat/fatent.c:705
 fat_trim_fs+0x441/0xb80 fs/fat/fatent.c:794
 fat_ioctl_fitrim fs/fat/file.c:146 [inline]
 fat_generic_ioctl+0x48e/0x7d0 fs/fat/file.c:169
 fat_dir_ioctl+0xc4/0x1d0 fs/fat/dir.c:816
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1816/0x3000 arch/x86/include/generated/asm/syscalls_64.h:17
 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 0xffff8881005f0bb8 of 8 bytes by task 12580 on cpu 0:
 nr_blockdev_pages+0x7e/0xd0 block/bdev.c:523
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 handshake_net_init+0x78/0x150 net/handshake/netlink.c:184
 ops_init+0x22a/0x2e0 net/core/net_namespace.c:137
 setup_net+0x83/0x210 net/core/net_namespace.c:445
 copy_net_ns+0x28c/0x3b0 net/core/net_namespace.c:580
 create_new_namespaces+0x20e/0x3d0 kernel/nsproxy.c:110
 unshare_nsproxy_namespaces+0xe8/0x120 kernel/nsproxy.c:218
 ksys_unshare+0x3d0/0x6d0 kernel/fork.c:3129
 __do_sys_unshare kernel/fork.c:3200 [inline]
 __se_sys_unshare kernel/fork.c:3198 [inline]
 __x64_sys_unshare+0x1f/0x30 kernel/fork.c:3198
 x64_sys_call+0x2915/0x3000 arch/x86/include/generated/asm/syscalls_64.h:273
 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

value changed: 0x0000000000000005 -> 0x0000000000000006

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12580 Comm: syz.2.3147 Not tainted syzkaller #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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