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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86703c18 of 8 bytes by task 25606 on cpu 0:
 prb_reserve+0x740/0xb60
 vprintk_store+0x558/0x870 kernel/printk/printk.c:2326
 vprintk_emit+0x15e/0x680 kernel/printk/printk.c:2408
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2447
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:86
 _printk+0x7a/0xa0 kernel/printk/printk.c:2457
 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline]
 show_trace_log_lvl+0x380/0x400 arch/x86/kernel/dumpstack.c:285
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0xf2/0x150 lib/dump_stack.c:120
 dump_stack+0x15/0x1a lib/dump_stack.c:129
 fail_dump lib/fault-inject.c:53 [inline]
 should_fail_ex+0x223/0x230 lib/fault-inject.c:154
 should_fail+0xb/0x10 lib/fault-inject.c:164
 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37
 _inline_copy_from_user include/linux/uaccess.h:163 [inline]
 _copy_from_user+0x1e/0xb0 lib/usercopy.c:18
 copy_from_user include/linux/uaccess.h:212 [inline]
 copy_from_bpfptr_offset include/linux/bpfptr.h:53 [inline]
 copy_from_bpfptr include/linux/bpfptr.h:59 [inline]
 __sys_bpf+0x14e/0x7a0 kernel/bpf/syscall.c:5763
 __do_sys_bpf kernel/bpf/syscall.c:5897 [inline]
 __se_sys_bpf kernel/bpf/syscall.c:5895 [inline]
 __x64_sys_bpf+0x43/0x50 kernel/bpf/syscall.c:5895
 x64_sys_call+0x2914/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:322
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86703c18 of 8 bytes by task 25608 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:486 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:1957 [inline]
 _prb_read_valid+0x3bb/0xba0 kernel/printk/printk_ringbuffer.c:2114
 prb_read_valid_info+0x67/0x90 kernel/printk/printk_ringbuffer.c:2216
 find_first_fitting_seq+0x1bc/0x310 kernel/printk/printk.c:1589
 syslog_print_all+0x12e/0x5c0 kernel/printk/printk.c:1721
 do_syslog+0x431/0x7f0 kernel/printk/printk.c:1799
 __do_sys_syslog kernel/printk/printk.c:1877 [inline]
 __se_sys_syslog kernel/printk/printk.c:1875 [inline]
 __x64_sys_syslog+0x43/0x50 kernel/printk/printk.c:1875
 x64_sys_call+0x29be/0x2dc0 arch/x86/include/generated/asm/syscalls_64.h:104
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000001451 -> 0x0000000000000000

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 25608 Comm: syz.5.7315 Not tainted 6.13.0-rc4-syzkaller-00012-g9b2ffa6148b1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/13/2024
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