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BUG: KCSAN: data-race in __filemap_add_folio / nr_blockdev_pages

read-write to 0xffff8881004c1830 of 8 bytes by task 3291 on cpu 0:
 __filemap_add_folio+0x4c1/0x730 mm/filemap.c:903
 filemap_add_folio+0x70/0x160 mm/filemap.c:938
 page_cache_ra_unbounded+0x15e/0x2e0 mm/readahead.c:250
 do_page_cache_ra mm/readahead.c:299 [inline]
 force_page_cache_ra mm/readahead.c:330 [inline]
 page_cache_sync_ra+0x24b/0x2a0 mm/readahead.c:689
 page_cache_sync_readahead include/linux/pagemap.h:1300 [inline]
 filemap_get_pages+0x251/0xf90 mm/filemap.c:2498
 filemap_read+0x214/0x680 mm/filemap.c:2594
 blkdev_read_iter+0x217/0x2c0 block/fops.c:757
 call_read_iter include/linux/fs.h:2079 [inline]
 new_sync_read fs/read_write.c:395 [inline]
 vfs_read+0x5ab/0x6a0 fs/read_write.c:476
 ksys_read+0xeb/0x1a0 fs/read_write.c:619
 __do_sys_read fs/read_write.c:629 [inline]
 __se_sys_read fs/read_write.c:627 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:627
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffff8881004c1830 of 8 bytes by task 3626 on cpu 1:
 nr_blockdev_pages+0x7c/0xd0 block/bdev.c:449
 si_meminfo+0x87/0xd0 mm/show_mem.c:80
 handshake_net_init+0x7a/0x140 net/handshake/netlink.c:184
 ops_init+0x1fc/0x2c0 net/core/net_namespace.c:136
 setup_net+0x2cd/0x710 net/core/net_namespace.c:339
 copy_net_ns+0x384/0x520 net/core/net_namespace.c:495
 create_new_namespaces+0x228/0x430 kernel/nsproxy.c:110
 copy_namespaces+0x1a9/0x200 kernel/nsproxy.c:179
 copy_process+0x1029/0x20a0 kernel/fork.c:2500
 kernel_clone+0x169/0x560 kernel/fork.c:2902
 __do_sys_clone kernel/fork.c:3045 [inline]
 __se_sys_clone kernel/fork.c:3029 [inline]
 __x64_sys_clone+0xe8/0x120 kernel/fork.c:3029
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000000000007 -> 0x0000000000000008

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 3626 Comm: syz-executor.2 Not tainted 6.8.0-rc3-syzkaller-00047-g047371968ffc #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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