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BUG: KCSAN: data-race in copy_page_to_iter / fat12_ent_put

write to 0xffff888137e35204 of 1 bytes by task 15222 on cpu 0:
 fat12_ent_put+0xce/0x180 fs/fat/fatent.c:164
 fat_free_clusters+0x2aa/0x870 fs/fat/fatent.c:596
 fat_alloc_new_dir+0x4b7/0x500 fs/fat/dir.c:1192
 vfat_mkdir+0x81/0x230 fs/fat/namei_vfat.c:861
 vfs_mkdir+0x2c8/0x3d0 fs/namei.c:3883
 do_mkdirat+0x12e/0x2c0 fs/namei.c:3909
 __do_sys_mkdirat fs/namei.c:3924 [inline]
 __se_sys_mkdirat fs/namei.c:3922 [inline]
 __x64_sys_mkdirat+0x4c/0x60 fs/namei.c:3922
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff888137e35000 of 1377 bytes by task 11571 on cpu 1:
 instrument_copy_to_user include/linux/instrumented.h:119 [inline]
 copyout lib/iov_iter.c:156 [inline]
 copy_page_to_iter_iovec lib/iov_iter.c:228 [inline]
 __copy_page_to_iter lib/iov_iter.c:852 [inline]
 copy_page_to_iter+0x2cb/0x950 lib/iov_iter.c:880
 filemap_read+0x138b/0x16d0 mm/filemap.c:2697
 generic_file_read_iter+0x72/0x2a0 mm/filemap.c:2792
 blkdev_read_iter+0x96/0x140 block/fops.c:583
 call_read_iter include/linux/fs.h:2156 [inline]
 new_sync_read fs/read_write.c:400 [inline]
 vfs_read+0x66c/0x750 fs/read_write.c:481
 ksys_read+0xd9/0x190 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+0x3e/0x50 fs/read_write.c:627
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 11571 Comm: udevd Not tainted 5.16.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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