loop5: detected capacity change from 0 to 545
==================================================================
BUG: KCSAN: data-race in kthread_is_per_cpu / page_cache_ra_unbounded

write to 0xffff8881315d602c of 4 bytes by task 23404 on cpu 1:
 memalloc_nofs_restore include/linux/sched/mm.h:259 [inline]
 page_cache_ra_unbounded+0x3e3/0x410 mm/readahead.c:239
 do_page_cache_ra mm/readahead.c:267 [inline]
 force_page_cache_ra+0x246/0x280 mm/readahead.c:299
 page_cache_sync_ra+0xcc/0xe0 mm/readahead.c:573
 page_cache_sync_readahead include/linux/pagemap.h:874 [inline]
 filemap_get_pages mm/filemap.c:2483 [inline]
 filemap_read+0x388/0x1230 mm/filemap.c:2566
 generic_file_read_iter+0x75/0x2c0 mm/filemap.c:2717
 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1720
 call_read_iter include/linux/fs.h:2110 [inline]
 new_sync_read fs/read_write.c:415 [inline]
 vfs_read+0x565/0x5d0 fs/read_write.c:496
 ksys_read+0xce/0x180 fs/read_write.c:634
 __do_sys_read fs/read_write.c:644 [inline]
 __se_sys_read fs/read_write.c:642 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:642
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff8881315d602c of 4 bytes by task 23410 on cpu 0:
 __to_kthread kernel/kthread.c:101 [inline]
 kthread_is_per_cpu+0x2d/0x80 kernel/kthread.c:540
 can_migrate_task+0xf/0x180 kernel/sched/fair.c:7615
 detach_tasks+0xab/0x380 kernel/sched/fair.c:7779
 load_balance+0x768/0xcc0 kernel/sched/fair.c:9679
 newidle_balance+0x10b/0x310 kernel/sched/fair.c:10643
 pick_next_task_fair+0x37/0x270 kernel/sched/fair.c:7203
 pick_next_task kernel/sched/core.c:4960 [inline]
 __schedule+0x256/0x5b0 kernel/sched/core.c:5111
 schedule+0x67/0x90 kernel/sched/core.c:5226
 io_schedule+0x3b/0x50 kernel/sched/core.c:7215
 bit_wait_io+0x8/0x50 kernel/sched/wait_bit.c:209
 __wait_on_bit kernel/sched/wait_bit.c:49 [inline]
 out_of_line_wait_on_bit+0xb6/0x110 kernel/sched/wait_bit.c:64
 wait_on_bit_io include/linux/wait_bit.h:101 [inline]
 __wait_on_buffer+0x54/0x60 fs/buffer.c:122
 wait_on_buffer include/linux/buffer_head.h:354 [inline]
 ext4_read_bh+0x153/0x190 fs/ext4/super.c:184
 ext4_read_bh_lock fs/ext4/super.c:194 [inline]
 __ext4_sb_bread_gfp fs/ext4/super.c:226 [inline]
 ext4_sb_bread_unmovable+0xf1/0x1d0 fs/ext4/super.c:243
 ext4_fill_super+0x41f/0x8010 fs/ext4/super.c:4089
 mount_bdev+0x1e8/0x290 fs/super.c:1367
 ext4_mount+0x2d/0x40 fs/ext4/super.c:6632
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:592
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 do_new_mount fs/namespace.c:2905 [inline]
 path_mount+0x11d4/0x1ce0 fs/namespace.c:3235
 do_mount fs/namespace.c:3248 [inline]
 __do_sys_mount fs/namespace.c:3456 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3433
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3433
 do_syscall_64+0x4a/0x90 arch/x86/entry/common.c:47
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 23410 Comm: syz-executor.5 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
EXT4-fs (loop5): ext4_check_descriptors: Block bitmap for group 0 overlaps superblock
EXT4-fs (loop5): group descriptors corrupted!