loop2: detected capacity change from 0 to 512
==================================================================
BUG: KCSAN: data-race in find_get_block_common / has_bh_in_lru

read-write to 0xffff888237c26fd0 of 8 bytes by task 21396 on cpu 0:
 bh_lru_install fs/buffer.c:1345 [inline]
 find_get_block_common+0x4f0/0x960 fs/buffer.c:1410
 __getblk_slow fs/buffer.c:-1 [inline]
 bdev_getblk+0x30d/0x3b0 fs/buffer.c:1461
 __getblk include/linux/buffer_head.h:380 [inline]
 sb_getblk include/linux/buffer_head.h:386 [inline]
 __ext4_get_inode_loc+0x303/0x930 fs/ext4/inode.c:4837
 __ext4_get_inode_loc_noinmem fs/ext4/inode.c:4950 [inline]
 __ext4_iget+0x2ea/0x22d0 fs/ext4/inode.c:5225
 __ext4_fill_super fs/ext4/super.c:5512 [inline]
 ext4_fill_super+0x2992/0x3810 fs/ext4/super.c:5736
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1698
 get_tree_bdev+0x1f/0x30 fs/super.c:1721
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5768
 vfs_get_tree+0x57/0x1d0 fs/super.c:1758
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3642 [inline]
 do_new_mount+0x24d/0x660 fs/namespace.c:3718
 path_mount+0x4a5/0xb70 fs/namespace.c:4028
 do_mount fs/namespace.c:4041 [inline]
 __do_sys_mount fs/namespace.c:4229 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4206
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4206
 x64_sys_call+0x2b51/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 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 0xffff888237c26fd0 of 8 bytes by task 21399 on cpu 1:
 has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1551
 smp_call_function_many_cond+0x2a9/0xc60 kernel/smp.c:821
 on_each_cpu_cond_mask+0x3c/0x80 kernel/smp.c:1043
 on_each_cpu_cond include/linux/smp.h:105 [inline]
 invalidate_bh_lrus+0x2a/0x30 fs/buffer.c:1560
 kill_bdev block/bdev.c:90 [inline]
 set_blocksize+0x24f/0x310 block/bdev.c:207
 sb_set_blocksize+0x7a/0x100 block/bdev.c:224
 ext4_load_super fs/ext4/super.c:5123 [inline]
 __ext4_fill_super fs/ext4/super.c:5275 [inline]
 ext4_fill_super+0x146c/0x3810 fs/ext4/super.c:5736
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1698
 get_tree_bdev+0x1f/0x30 fs/super.c:1721
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5768
 vfs_get_tree+0x57/0x1d0 fs/super.c:1758
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3642 [inline]
 do_new_mount+0x24d/0x660 fs/namespace.c:3718
 path_mount+0x4a5/0xb70 fs/namespace.c:4028
 do_mount fs/namespace.c:4041 [inline]
 __do_sys_mount fs/namespace.c:4229 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4206
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4206
 x64_sys_call+0x2b51/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 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: 0xffff888106e7d548 -> 0xffff88810e63a958

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 21399 Comm: syz.2.5342 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
==================================================================
EXT4-fs error (device loop2): ext4_empty_dir:3086: inode #12: block 32: comm syz.2.5342: bad entry in directory: rec_len is too small for name_len - offset=0, inode=12, rec_len=12, size=2048 fake=0
EXT4-fs warning (device loop2): ext4_empty_dir:3089: inode #12: comm syz.2.5342: directory missing '.'