loop4: p4 size 3657465856 extends beyond EOD, truncated
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BUG: KCSAN: data-race in pcpu_alloc / pcpu_free_area

write to 0xffffffff8455f74c of 4 bytes by interrupt on cpu 1:
 pcpu_update_empty_pages mm/percpu.c:559 [inline]
 pcpu_block_update_hint_free mm/percpu.c:994 [inline]
 pcpu_free_area+0x50c/0x5a0 mm/percpu.c:1254
 free_percpu+0x1d2/0x690 mm/percpu.c:2102
 bdev_free_inode+0x2a/0x60 fs/block_dev.c:812
 i_callback+0x2e/0x60 fs/inode.c:222
 rcu_do_batch kernel/rcu/tree.c:2558 [inline]
 rcu_core+0xb95/0xd50 kernel/rcu/tree.c:2793
 rcu_core_si+0x9/0x10 kernel/rcu/tree.c:2806
 __do_softirq+0x12c/0x275 kernel/softirq.c:559
 run_ksoftirqd+0x13/0x20 kernel/softirq.c:921
 smpboot_thread_fn+0x2a1/0x3f0 kernel/smpboot.c:165
 kthread+0x1d0/0x1f0 kernel/kthread.c:313
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

read to 0xffffffff8455f74c of 4 bytes by task 21489 on cpu 0:
 pcpu_alloc+0xa33/0x1200 mm/percpu.c:1835
 __alloc_percpu+0x20/0x30 mm/percpu.c:1907
 bdev_alloc+0x117/0x160 fs/block_dev.c:907
 add_partition+0x155/0x580 block/partitions/core.c:356
 blk_add_partition block/partitions/core.c:586 [inline]
 blk_add_partitions+0x583/0xa80 block/partitions/core.c:653
 bdev_disk_changed+0x2a1/0x310 fs/block_dev.c:1271
 loop_reread_partitions drivers/block/loop.c:656 [inline]
 loop_set_status+0x75f/0x7e0 drivers/block/loop.c:1419
 lo_ioctl+0x758/0x11f0 drivers/block/loop.c:1487
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585
 block_ioctl+0x6d/0x80 fs/block_dev.c:1664
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:1069 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:1055
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:1055
 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: 21489 Comm: syz-executor.4 Tainted: G        W         5.13.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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