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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve_in_last

write to 0xffffffff8686a768 of 8 bytes by task 12330 on cpu 0:
 data_realloc kernel/printk/printk_ringbuffer.c:1177 [inline]
 prb_reserve_in_last+0x861/0xb80 kernel/printk/printk_ringbuffer.c:1440
 vprintk_store+0x494/0x860 kernel/printk/printk.c:2300
 vprintk_emit+0x178/0x650 kernel/printk/printk.c:2426
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2465
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2475
 show_free_areas mm/show_mem.c:346 [inline]
 __show_mem+0xd8b/0x14b0 mm/show_mem.c:403
 warn_alloc_show_mem mm/page_alloc.c:3719 [inline]
 warn_alloc+0x189/0x1a0 mm/page_alloc.c:3744
 __vmalloc_area_node mm/vmalloc.c:3702 [inline]
 __vmalloc_node_range_noprof+0x497/0xe00 mm/vmalloc.c:3893
 __vmalloc_node_noprof mm/vmalloc.c:3956 [inline]
 __vmalloc_noprof+0x83/0xc0 mm/vmalloc.c:3970
 bpf_prog_alloc_no_stats+0x47/0x390 kernel/bpf/core.c:104
 bpf_prog_alloc+0x3c/0x150 kernel/bpf/core.c:146
 bpf_prog_load+0x514/0x1070 kernel/bpf/syscall.c:2882
 __sys_bpf+0x51d/0x790 kernel/bpf/syscall.c:5836
 __do_sys_bpf kernel/bpf/syscall.c:5943 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5941 [inline]
 __x64_sys_bpf+0x41/0x50 kernel/bpf/syscall.c:5941
 x64_sys_call+0x2478/0x2fb0 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xd2/0x200 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff8686a760 of 16 bytes by task 12340 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1874 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1922 [inline]
 _prb_read_valid+0x1bc/0x920 kernel/printk/printk_ringbuffer.c:2113
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2185
 printk_get_next_message+0xc8/0x510 kernel/printk/printk.c:3005
 console_emit_next_record kernel/printk/printk.c:3092 [inline]
 console_flush_all+0x290/0x730 kernel/printk/printk.c:3226
 __console_flush_and_unlock kernel/printk/printk.c:3285 [inline]
 console_unlock+0xa1/0x330 kernel/printk/printk.c:3325
 con_shutdown+0x4b/0x60 drivers/tty/vt/vt.c:3651
 release_tty+0x85/0x4f0 drivers/tty/tty_io.c:1580
 tty_release_struct+0x96/0xb0 drivers/tty/tty_io.c:1692
 tty_release+0x856/0xb10 drivers/tty/tty_io.c:1852
 __fput+0x29b/0x650 fs/file_table.c:465
 ____fput+0x1c/0x30 fs/file_table.c:493
 task_work_run+0x131/0x1a0 kernel/task_work.c:227
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 exit_to_user_mode_loop+0xe4/0x100 kernel/entry/common.c:114
 exit_to_user_mode_prepare include/linux/entry-common.h:330 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:414 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:449 [inline]
 do_syscall_64+0x1d6/0x200 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 12340 Comm: syz.2.2857 Not tainted 6.16.0-rc7-syzkaller-00018-g01a412d06bc5 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
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