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BUG: KCSAN: data-race in console_unlock / console_unlock

write to 0xffffffff8417d940 of 8 bytes by task 26030 on cpu 0:
 console_unlock+0x570/0xb30 kernel/printk/printk.c:2632
 vprintk_emit+0x125/0x3d0 kernel/printk/printk.c:2174
 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
 __should_failslab+0x81/0x90 mm/failslab.c:33
 should_failslab+0x5/0x20 mm/slab_common.c:1326
 slab_pre_alloc_hook mm/slab.h:494 [inline]
 slab_alloc_node mm/slab.c:3222 [inline]
 kmem_cache_alloc_node_trace+0x58/0x2e0 mm/slab.c:3617
 __do_kmalloc_node mm/slab.c:3639 [inline]
 __kmalloc_node_track_caller+0x30/0x40 mm/slab.c:3654
 kmalloc_reserve net/core/skbuff.c:355 [inline]
 __alloc_skb+0x187/0x420 net/core/skbuff.c:426
 alloc_skb include/linux/skbuff.h:1112 [inline]
 alloc_skb_with_frags+0x90/0x390 net/core/skbuff.c:6019
 sock_alloc_send_pskb+0x436/0x4e0 net/core/sock.c:2461
 sock_alloc_send_skb+0x2d/0x40 net/core/sock.c:2478
 __ip6_append_data+0x17ed/0x22b0 net/ipv6/ip6_output.c:1653
 ip6_make_skb+0x258/0x420 net/ipv6/ip6_output.c:2014
 udpv6_sendmsg+0x160a/0x16b0 net/ipv6/udp.c:1540
 inet6_sendmsg+0x5f/0x80 net/ipv6/af_inet6.c:642
 sock_sendmsg_nosec net/socket.c:703 [inline]
 sock_sendmsg net/socket.c:723 [inline]
 ____sys_sendmsg+0x360/0x4d0 net/socket.c:2392
 ___sys_sendmsg net/socket.c:2446 [inline]
 __sys_sendmmsg+0x315/0x4b0 net/socket.c:2532
 __do_sys_sendmmsg net/socket.c:2561 [inline]
 __se_sys_sendmmsg net/socket.c:2558 [inline]
 __x64_sys_sendmmsg+0x53/0x60 net/socket.c:2558
 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 0xffffffff8417d940 of 8 bytes by task 26003 on cpu 1:
 console_unlock+0x9f5/0xb30 kernel/printk/printk.c:2667
 do_con_write+0x5d29/0x5d90 drivers/tty/vt/vt.c:270
 con_put_char+0x35/0x60 drivers/tty/vt/vt.c:3263
 tty_put_char+0x5f/0xa0 drivers/tty/tty_io.c:3173
 do_output_char+0x4ca/0x4f0 drivers/tty/n_tty.c:485
 process_output drivers/tty/n_tty.c:511 [inline]
 n_tty_write+0x7f8/0xaf0 drivers/tty/n_tty.c:2300
 do_tty_write drivers/tty/tty_io.c:1038 [inline]
 file_tty_write+0x409/0x660 drivers/tty/tty_io.c:1110
 tty_write+0x24/0x30 drivers/tty/tty_io.c:1131
 call_write_iter include/linux/fs.h:2114 [inline]
 do_iter_readv_writev+0x2cb/0x360 fs/read_write.c:740
 do_iter_write+0x112/0x4c0 fs/read_write.c:866
 vfs_writev fs/read_write.c:939 [inline]
 do_writev+0x1e0/0x400 fs/read_write.c:982
 __do_sys_writev fs/read_write.c:1055 [inline]
 __se_sys_writev fs/read_write.c:1052 [inline]
 __x64_sys_writev+0x41/0x50 fs/read_write.c:1052
 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: 0x0000000000004d05 -> 0x0000000000004d06

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 26003 Comm: syz-executor.1 Not tainted 5.14.0-rc6-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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