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BUG: KCSAN: data-race in __find_get_block / has_bh_in_lru

read to 0xffff88812c12a1c0 of 8 bytes by task 4565 on cpu 0:
 has_bh_in_lru+0x44/0x90 fs/buffer.c:1427
 on_each_cpu_cond_mask+0xa3/0x150 kernel/smp.c:695
 on_each_cpu_cond+0x44/0x60 kernel/smp.c:721
 invalidate_bh_lrus+0x32/0x40 fs/buffer.c:1436
 kill_bdev+0x7f/0xb0 fs/block_dev.c:85
 set_blocksize+0x1dd/0x210 fs/block_dev.c:136
 sb_set_blocksize+0x3d/0xc0 fs/block_dev.c:145
 sb_min_blocksize+0xa5/0xc0 fs/block_dev.c:161
 fat_fill_super+0x1da/0x1f50 fs/fat/inode.c:1646
 vfat_fill_super+0x3b/0x50 fs/fat/namei_vfat.c:1050
 mount_bdev+0x262/0x2d0 fs/super.c:1415
 vfat_mount+0x3e/0x60 fs/fat/namei_vfat.c:1057
 legacy_get_tree+0x7e/0xf0 fs/fs_context.c:647
 vfs_get_tree+0x56/0x1a0 fs/super.c:1545
 do_new_mount fs/namespace.c:2822 [inline]
 do_mount+0x1004/0x14f0 fs/namespace.c:3142
 ksys_mount+0xe8/0x160 fs/namespace.c:3351
 __do_sys_mount fs/namespace.c:3365 [inline]
 __se_sys_mount fs/namespace.c:3362 [inline]
 __x64_sys_mount+0x70/0x90 fs/namespace.c:3362
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

write to 0xffff88812c12a1c0 of 8 bytes by task 4699 on cpu 1:
 bh_lru_install fs/buffer.c:1279 [inline]
 __find_get_block fs/buffer.c:1338 [inline]
 __find_get_block+0x62b/0x760 fs/buffer.c:1330
 sb_find_get_block include/linux/buffer_head.h:338 [inline]
 recently_deleted fs/ext4/ialloc.c:677 [inline]
 find_inode_bit.isra.0+0x161/0x300 fs/ext4/ialloc.c:717
 __ext4_new_inode+0xd45/0x2f10 fs/ext4/ialloc.c:909
 ext4_symlink+0x31c/0x9b0 fs/ext4/namei.c:3275
 vfs_symlink fs/namei.c:4131 [inline]
 vfs_symlink+0x218/0x310 fs/namei.c:4117
 do_symlinkat+0x1a5/0x1e0 fs/namei.c:4158
 __do_sys_symlink fs/namei.c:4177 [inline]
 __se_sys_symlink fs/namei.c:4175 [inline]
 __x64_sys_symlink+0x3f/0x50 fs/namei.c:4175
 do_syscall_64+0xcc/0x3a0 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 4699 Comm: syz-executor.5 Not tainted 5.5.0-rc1-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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