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BUG: KCSAN: data-race in data_push_tail / symbol_string

write to 0xffffffff870e6dd1 of 1 bytes by task 728 on cpu 0:
 string_nocheck lib/vsprintf.c:650 [inline]
 symbol_string+0x1b6/0x240 lib/vsprintf.c:1006
 pointer+0x77a/0xd10 lib/vsprintf.c:2422
 vsnprintf+0x861/0xe30 lib/vsprintf.c:2828
 vscnprintf+0x42/0x80 lib/vsprintf.c:2930
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2124
 vprintk_store+0x56f/0x800 kernel/printk/printk.c:2238
 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2284
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline]
 show_trace_log_lvl+0x42e/0x510 arch/x86/kernel/dumpstack.c:285
 __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/slub.c:3747
 slab_pre_alloc_hook mm/slub.c:3763 [inline]
 slab_alloc_node mm/slub.c:3842 [inline]
 kmem_cache_alloc+0x56/0x2d0 mm/slub.c:3867
 vm_area_dup+0x2c/0x130 kernel/fork.c:480
 __split_vma+0xf8/0x610 mm/mmap.c:2335
 do_vmi_align_munmap+0x224/0x9c0 mm/mmap.c:2549
 do_vmi_munmap+0x1ea/0x230 mm/mmap.c:2695
 mmap_region+0x543/0x1640 mm/mmap.c:2746
 do_mmap+0x6a5/0xab0 mm/mmap.c:1379
 do_shmat+0x5b1/0x7b0 ipc/shm.c:1661
 __do_sys_shmat ipc/shm.c:1697 [inline]
 __se_sys_shmat ipc/shm.c:1692 [inline]
 __x64_sys_shmat+0x64/0xb0 ipc/shm.c:1692
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffffffff870e6dd0 of 8 bytes by task 829 on cpu 1:
 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+0x897/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2228
 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2284
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 fib6_add_rt2node net/ipv6/ip6_fib.c:1265 [inline]
 fib6_add+0x1b49/0x1f40 net/ipv6/ip6_fib.c:1477
 __ip6_ins_rt net/ipv6/route.c:1303 [inline]
 ip6_route_add+0x71/0x100 net/ipv6/route.c:3847
 inet6_rtm_newroute+0x177/0x1140 net/ipv6/route.c:5510
 rtnetlink_rcv_msg+0x80a/0x8c0 net/core/rtnetlink.c:6618
 netlink_rcv_skb+0x126/0x220 net/netlink/af_netlink.c:2543
 rtnetlink_rcv+0x1c/0x20 net/core/rtnetlink.c:6636
 netlink_unicast_kernel net/netlink/af_netlink.c:1341 [inline]
 netlink_unicast+0x589/0x660 net/netlink/af_netlink.c:1367
 netlink_sendmsg+0x66e/0x770 net/netlink/af_netlink.c:1908
 sock_sendmsg_nosec net/socket.c:730 [inline]
 __sock_sendmsg net/socket.c:745 [inline]
 ____sys_sendmsg+0x37c/0x4d0 net/socket.c:2584
 ___sys_sendmsg net/socket.c:2638 [inline]
 __sys_sendmsg+0x1e9/0x270 net/socket.c:2667
 __do_sys_sendmsg net/socket.c:2676 [inline]
 __se_sys_sendmsg net/socket.c:2674 [inline]
 __x64_sys_sendmsg+0x46/0x50 net/socket.c:2674
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x0000000100005399 -> 0x0000000100005320

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 829 Comm: syz-executor.3 Not tainted 6.8.0-rc6-syzkaller-00024-ge326df53af00 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
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