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BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff8414898a of 1 bytes by task 1041 on cpu 1:
 vsnprintf+0xe8f/0xed0 lib/vsprintf.c:2869
 vscnprintf+0x29/0x80 lib/vsprintf.c:2900
 printk_sprint kernel/printk/printk.c:2012 [inline]
 vprintk_store+0x353/0x9c0 kernel/printk/printk.c:2084
 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
 printk+0x62/0x87 kernel/printk/printk.c:2216
 disk_unlock_native_capacity block/partitions/core.c:537 [inline]
 blk_add_partition block/partitions/core.c:577 [inline]
 blk_add_partitions block/partitions/core.c:655 [inline]
 bdev_disk_changed+0xac4/0xea0 block/partitions/core.c:697
 blkdev_get_whole+0x2f2/0x350 fs/block_dev.c:1269
 blkdev_get_by_dev+0x2ad/0x8d0 fs/block_dev.c:1417
 blkdev_reread_part block/ioctl.c:102 [inline]
 blkdev_common_ioctl+0xfc8/0x1040 block/ioctl.c:510
 blkdev_ioctl+0x16e/0x3c0 block/ioctl.c:579
 block_ioctl+0x6d/0x80 fs/block_dev.c:1604
 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_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff84148988 of 8 bytes by task 31684 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x125/0x460 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x8f0/0xbc0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x3e9/0x9c0 kernel/printk/printk.c:2105
 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
 printk+0x62/0x87 kernel/printk/printk.c:2216
 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline]
 show_trace_log_lvl+0x587/0x600 arch/x86/kernel/dumpstack.c:282
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xb7/0x103 lib/dump_stack.c:105
 dump_stack+0x11/0x1a lib/dump_stack.c:112
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x23c/0x250 lib/fault-inject.c:146
 prepare_alloc_pages mm/page_alloc.c:5172 [inline]
 __alloc_pages+0x102/0x320 mm/page_alloc.c:5380
 alloc_pages_vma+0x513/0x680 mm/mempolicy.c:2208
 new_page+0x124/0x170 mm/mempolicy.c:1236
 unmap_and_move mm/migrate.c:1132 [inline]
 migrate_pages+0x3b3/0x1530 mm/migrate.c:1411
 do_mbind+0xd43/0xf50 mm/mempolicy.c:1340
 kernel_mbind mm/mempolicy.c:1475 [inline]
 __do_sys_mbind mm/mempolicy.c:1482 [inline]
 __se_sys_mbind mm/mempolicy.c:1478 [inline]
 __x64_sys_mbind+0x10a/0x130 mm/mempolicy.c:1478
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000001000017da -> 0x0000000100000a64

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 31684 Comm: syz-executor.0 Not tainted 5.14.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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