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BUG: KCSAN: data-race in _prb_read_valid / data_alloc

write to 0xffffffff86c699e8 of 8 bytes by task 16055 on cpu 0:
 data_alloc+0x2fc/0x380 kernel/printk/printk_ringbuffer.c:1129
 prb_reserve+0x8e3/0xaf0 kernel/printk/printk_ringbuffer.c:1727
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2354
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2455
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2494
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2504
 __oom_kill_process+0x395/0x7f0 mm/oom_kill.c:945
 oom_kill_process+0xf4/0x350 mm/oom_kill.c:1042
 out_of_memory+0x981/0xbc0 mm/oom_kill.c:1169
 mem_cgroup_out_of_memory mm/memcontrol.c:1907 [inline]
 mem_cgroup_oom mm/memcontrol.c:1930 [inline]
 try_charge_memcg+0x621/0xa00 mm/memcontrol.c:2697
 obj_cgroup_charge_pages mm/memcontrol.c:3097 [inline]
 __memcg_kmem_charge_page+0x199/0x3a0 mm/memcontrol.c:3141
 __alloc_frozen_pages_noprof+0x18a/0x350 mm/page_alloc.c:5321
 alloc_pages_mpol+0xa9/0x1d0 mm/mempolicy.c:2490
 alloc_frozen_pages_noprof mm/mempolicy.c:2561 [inline]
 alloc_pages_noprof+0x8f/0x140 mm/mempolicy.c:2581
 vm_area_alloc_pages mm/vmalloc.c:3742 [inline]
 __vmalloc_area_node mm/vmalloc.c:3892 [inline]
 __vmalloc_node_range_noprof+0xae9/0x11e0 mm/vmalloc.c:4082
 __kvmalloc_node_noprof+0x3a0/0x590 mm/slub.c:6933
 futex_hash_allocate+0x192/0x920 kernel/futex/core.c:1823
 futex_hash_prctl+0xd8/0xf0 kernel/futex/core.c:1995
 __do_sys_prctl kernel/sys.c:2885 [inline]
 __se_sys_prctl+0x4f4/0x13b0 kernel/sys.c:2534
 __x64_sys_prctl+0x67/0x80 kernel/sys.c:2534
 x64_sys_call+0x2533/0x3020 arch/x86/include/generated/asm/syscalls_64.h:158
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86c699e8 of 16 bytes by task 16081 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:496 [inline]
 desc_read_finalized_seq kernel/printk/printk_ringbuffer.c:1934 [inline]
 prb_read kernel/printk/printk_ringbuffer.c:1982 [inline]
 _prb_read_valid+0x183/0x930 kernel/printk/printk_ringbuffer.c:2173
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2245
 __console_flush_and_unlock kernel/printk/printk.c:3392 [inline]
 console_unlock+0x146/0x280 kernel/printk/printk.c:3413
 class_console_lock_destructor include/linux/console.h:734 [inline]
 vt_resizex+0x3b7/0x3d0 drivers/tty/vt/vt_ioctl.c:718
 vt_ioctl+0x1091/0x1900 drivers/tty/vt/vt_ioctl.c:923
 tty_ioctl+0x7d7/0xb80 drivers/tty/tty_io.c:2792
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:597 [inline]
 __se_sys_ioctl+0xce/0x140 fs/ioctl.c:583
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:583
 x64_sys_call+0x1563/0x3020 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 16081 Comm: syz.7.4571 Tainted: G        W           syzkaller #0 PREEMPT(lazy) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
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