EXT4-fs error (device loop4) in ext4_mb_clear_bb:6678: Corrupt filesystem
loop4: lost filesystem error report for type 5 error -117
==================================================================
BUG: KCSAN: data-race in _copy_to_iter / memcpy_and_pad

read to 0xffff88812c3dd400 of 1024 bytes by task 3287 on cpu 1:
 instrument_copy_to_user include/linux/instrumented.h:130 [inline]
 copy_to_user_iter lib/iov_iter.c:24 [inline]
 iterate_ubuf include/linux/iov_iter.h:30 [inline]
 iterate_and_advance2 include/linux/iov_iter.h:302 [inline]
 iterate_and_advance include/linux/iov_iter.h:332 [inline]
 _copy_to_iter+0x130/0xea0 lib/iov_iter.c:197
 copy_page_to_iter+0x174/0x210 lib/iov_iter.c:374
 copy_folio_to_iter include/linux/uio.h:212 [inline]
 filemap_read+0x3f8/0xad0 mm/filemap.c:2904
 blkdev_read_iter+0x29c/0x390 block/fops.c:896
 new_sync_read fs/read_write.c:493 [inline]
 vfs_read+0x699/0x7c0 fs/read_write.c:574
 ksys_read+0xdc/0x1a0 fs/read_write.c:716
 __do_sys_read fs/read_write.c:725 [inline]
 __se_sys_read fs/read_write.c:723 [inline]
 __x64_sys_read+0x40/0x50 fs/read_write.c:723
 x64_sys_call+0x2135/0x2550 arch/x86/include/generated/asm/syscalls_64.h:1
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

write to 0xffff88812c3dd5f0 of 16 bytes by task 12062 on cpu 0:
 memcpy_and_pad+0x5a/0x80 lib/string_helpers.c:1009
 ext4_update_super+0x78b/0xb90 fs/ext4/super.c:6361
 ext4_commit_super+0x40/0x260 fs/ext4/super.c:6390
 ext4_handle_error+0x46f/0x570 fs/ext4/super.c:736
 __ext4_std_error+0x174/0x340 fs/ext4/super.c:992
 ext4_mb_clear_bb fs/ext4/mballoc.c:6678 [inline]
 ext4_free_blocks+0x132b/0x1420 fs/ext4/mballoc.c:6781
 ext4_free_branches+0x313/0x430 fs/ext4/indirect.c:1100
 ext4_ind_truncate+0x5ef/0x840 fs/ext4/indirect.c:1181
 ext4_truncate+0x690/0xa50 fs/ext4/inode.c:5517
 ext4_process_orphan+0x10b/0x1c0 fs/ext4/orphan.c:338
 ext4_orphan_cleanup+0x753/0xab0 fs/ext4/orphan.c:473
 __ext4_fill_super fs/ext4/super.c:5769 [inline]
 ext4_fill_super+0x340a/0x37d0 fs/ext4/super.c:5899
 get_tree_bdev_flags+0x297/0x300 fs/super.c:1821
 get_tree_bdev+0x1f/0x30 fs/super.c:1844
 ext4_get_tree+0x1c/0x30 fs/ext4/super.c:5931
 vfs_get_tree+0x57/0x1d0 fs/super.c:1881
 fc_mount fs/namespace.c:1282 [inline]
 do_new_mount_fc fs/namespace.c:3910 [inline]
 do_new_mount+0x288/0x730 fs/namespace.c:3986
 path_mount+0x4ad/0xba0 fs/namespace.c:4337
 do_mount fs/namespace.c:4350 [inline]
 __do_sys_mount fs/namespace.c:4565 [inline]
 __se_sys_mount+0x28c/0x2e0 fs/namespace.c:4542
 __x64_sys_mount+0x67/0x80 fs/namespace.c:4542
 x64_sys_call+0xc3b/0x2550 arch/x86/include/generated/asm/syscalls_64.h:166
 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline]
 do_syscall_64+0x112/0x360 arch/x86/entry/syscall_64.c:84
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 12062 Comm: syz.4.1674 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/15/2026
==================================================================
EXT4-fs (loop4): 2 truncates cleaned up