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BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff86f317e0 of 1 bytes by task 2788 on cpu 1:
 number+0x7d0/0xa90 lib/vsprintf.c:562
 vsnprintf+0xa44/0xe20 lib/vsprintf.c:2883
 vscnprintf+0x42/0x80 lib/vsprintf.c:2923
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2128
 vprintk_store+0x56f/0x800 kernel/printk/printk.c:2242
 vprintk_emit+0xd0/0x430 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x83/0x90 kernel/printk/printk_safe.c:50
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 show_ip arch/x86/kernel/dumpstack.c:142 [inline]
 show_iret_regs+0x26/0x60 arch/x86/kernel/dumpstack.c:149
 __show_regs+0x22/0x340 arch/x86/kernel/process_64.c:75
 show_trace_log_lvl+0x2bc/0x3d0 arch/x86/kernel/dumpstack.c:298
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0xda/0x130 lib/dump_stack.c:106
 dump_stack+0x15/0x20 lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x21f/0x230 lib/fault-inject.c:153
 __should_failslab+0x92/0xa0 mm/failslab.c:44
 should_failslab+0x9/0x20 mm/slab_common.c:1457
 slab_pre_alloc_hook+0x38/0x180 mm/slab.h:672
 slab_alloc_node mm/slab.c:3240 [inline]
 kmem_cache_alloc_node+0x5d/0x2e0 mm/slab.c:3528
 __alloc_skb+0x109/0x2e0 net/core/skbuff.c:644
 alloc_skb include/linux/skbuff.h:1288 [inline]
 netlink_alloc_large_skb net/netlink/af_netlink.c:1211 [inline]
 netlink_sendmsg+0x483/0x770 net/netlink/af_netlink.c:1888
 sock_sendmsg_nosec net/socket.c:724 [inline]
 sock_sendmsg net/socket.c:747 [inline]
 ____sys_sendmsg+0x375/0x4c0 net/socket.c:2503
 ___sys_sendmsg net/socket.c:2557 [inline]
 __sys_sendmsg+0x1e3/0x270 net/socket.c:2586
 __do_sys_sendmsg net/socket.c:2595 [inline]
 __se_sys_sendmsg net/socket.c:2593 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2593
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffffffff86f317e0 of 8 bytes by task 2789 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x893/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2232
 vprintk_emit+0xd0/0x430 kernel/printk/printk.c:2288
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x83/0x90 kernel/printk/printk_safe.c:50
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 set_capacity_and_notify+0x175/0x1d0 block/genhd.c:90
 loop_set_size+0x2e/0x70 drivers/block/loop.c:237
 loop_configure+0xaf6/0xca0 drivers/block/loop.c:1100
 lo_ioctl+0x682/0x12e0
 blkdev_ioctl+0x38e/0x480 block/ioctl.c:615
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x0000000100000c3e -> 0x6464663778303a33

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 2789 Comm: syz-executor.1 Not tainted 6.3.0-syzkaller-12423-g865fdb08197e #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/14/2023
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