loop1: detected capacity change from 0 to 512
==================================================================
BUG: KCSAN: data-race in find_get_block_common / has_bh_in_lru

read-write to 0xffff888237c27550 of 8 bytes by task 20352 on cpu 0:
 bh_lru_install fs/buffer.c:1345 [inline]
 find_get_block_common+0x498/0x8e0 fs/buffer.c:1410
 bdev_getblk+0x4d/0x3f0 include/linux/gfp.h:-1
 __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:4835
 ext4_get_inode_loc fs/ext4/inode.c:4963 [inline]
 ext4_reserve_inode_write+0xd7/0x250 fs/ext4/inode.c:6287
 __ext4_mark_inode_dirty+0x8c/0x3f0 fs/ext4/inode.c:6465
 ext4_dirty_inode+0x92/0xc0 fs/ext4/inode.c:6502
 __mark_inode_dirty+0x162/0x740 fs/fs-writeback.c:2595
 generic_update_time fs/inode.c:2158 [inline]
 inode_update_time fs/inode.c:2171 [inline]
 file_update_time_flags+0x2d3/0x300 fs/inode.c:2398
 file_update_time+0x17/0x20 fs/inode.c:2419
 ext4_page_mkwrite+0x18c/0xb90 fs/ext4/inode.c:6668
 do_page_mkwrite mm/memory.c:3531 [inline]
 do_shared_fault mm/memory.c:5834 [inline]
 do_fault mm/memory.c:5896 [inline]
 do_pte_missing mm/memory.c:4404 [inline]
 handle_pte_fault mm/memory.c:6276 [inline]
 __handle_mm_fault mm/memory.c:6414 [inline]
 handle_mm_fault+0x18fb/0x3030 mm/memory.c:6583
 do_user_addr_fault+0x62f/0x1050 arch/x86/mm/fault.c:1334
 handle_page_fault arch/x86/mm/fault.c:1474 [inline]
 exc_page_fault+0x62/0xa0 arch/x86/mm/fault.c:1527
 asm_exc_page_fault+0x26/0x30 arch/x86/include/asm/idtentry.h:618

read to 0xffff888237c27550 of 8 bytes by task 20355 on cpu 1:
 has_bh_in_lru+0x35/0x1f0 fs/buffer.c:1551
 smp_call_function_many_cond+0x2a9/0xc30 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+0x24a/0x310 block/bdev.c:207
 sb_set_blocksize+0x93/0x170 block/bdev.c:241
 sb_min_blocksize+0x53/0x60 block/bdev.c:256
 ext4_load_super fs/ext4/super.c:5091 [inline]
 __ext4_fill_super fs/ext4/super.c:5312 [inline]
 ext4_fill_super+0x3a1/0x3800 fs/ext4/super.c:5777
 get_tree_bdev_flags+0x291/0x300 fs/super.c:1691
 get_tree_bdev+0x1f/0x30 fs/super.c:1714
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5809
 vfs_get_tree+0x57/0x1d0 fs/super.c:1751
 fc_mount fs/namespace.c:1199 [inline]
 do_new_mount_fc fs/namespace.c:3636 [inline]
 do_new_mount+0x288/0x700 fs/namespace.c:3712
 path_mount+0x4d0/0xbc0 fs/namespace.c:4022
 do_mount fs/namespace.c:4035 [inline]
 __do_sys_mount fs/namespace.c:4224 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4201
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4201
 x64_sys_call+0x2cca/0x3000 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000000000 -> 0xffff8881075cd340

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 20355 Comm: syz.1.5338 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
==================================================================
EXT4-fs (loop1): mounting ext3 file system using the ext4 subsystem
EXT4-fs (loop1): orphan cleanup on readonly fs
EXT4-fs (loop1): 1 truncate cleaned up
EXT4-fs (loop1): mounted filesystem 00000000-0000-0000-0000-000000000000 ro without journal. Quota mode: none.