loop0: detected capacity change from 0 to 16
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BUG: KCSAN: data-race in kthread_is_per_cpu / page_cache_ra_unbounded

write to 0xffff88810090102c of 4 bytes by task 4693 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 0xffff88810090102c of 4 bytes by task 14134 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
 freezable_schedule include/linux/freezer.h:172 [inline]
 futex_wait_queue_me+0x1a1/0x260 kernel/futex.c:2606
 futex_wait+0x143/0x430 kernel/futex.c:2708
 do_futex+0x9e8/0x1ee0 kernel/futex.c:3733
 __do_sys_futex kernel/futex.c:3796 [inline]
 __se_sys_futex+0x2a8/0x390 kernel/futex.c:3762
 __x64_sys_futex+0x74/0x80 kernel/futex.c:3762
 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: 14134 Comm: syz-executor.0 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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