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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff86af78f8 of 88 bytes by task 9259 on cpu 0:
 prb_reserve+0x6e6/0xae0 kernel/printk/printk_ringbuffer.c:1690
 vprintk_store+0x54a/0x910 kernel/printk/printk.c:2302
 vprintk_emit+0x1a4/0x600 kernel/printk/printk.c:2402
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2441
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2451
 seq_buf_do_printk+0x113/0x1a0 lib/seq_buf.c:126
 mem_cgroup_print_oom_meminfo+0x17d/0x260 mm/memcontrol.c:1599
 dump_header+0xa2/0x240 mm/oom_kill.c:469
 oom_kill_process+0x295/0x350 mm/oom_kill.c:1047
 out_of_memory+0x97d/0xb80 mm/oom_kill.c:1185
 mem_cgroup_out_of_memory mm/memcontrol.c:1682 [inline]
 mem_cgroup_oom mm/memcontrol.c:1705 [inline]
 try_charge_memcg+0x62e/0xa10 mm/memcontrol.c:2430
 obj_cgroup_charge_pages+0xa6/0x150 mm/memcontrol.c:2823
 __memcg_kmem_charge_page+0x9e/0x170 mm/memcontrol.c:2867
 __alloc_frozen_pages_noprof+0x18a/0x350 mm/page_alloc.c:5257
 alloc_pages_mpol+0xb3/0x260 mm/mempolicy.c:2486
 alloc_frozen_pages_noprof mm/mempolicy.c:2557 [inline]
 alloc_pages_noprof+0x8f/0x130 mm/mempolicy.c:2577
 vm_area_alloc_pages mm/vmalloc.c:3718 [inline]
 __vmalloc_area_node mm/vmalloc.c:3863 [inline]
 __vmalloc_node_range_noprof+0xa46/0x12b0 mm/vmalloc.c:4051
 __kvmalloc_node_noprof+0x471/0x680 mm/slub.c:7164
 ip_set_alloc+0x24/0x30 net/netfilter/ipset/ip_set_core.c:261
 hash_netiface_create+0x282/0x740 net/netfilter/ipset/ip_set_hash_gen.h:1568
 ip_set_create+0x3cf/0x970 net/netfilter/ipset/ip_set_core.c:1109
 nfnetlink_rcv_msg+0x509/0x5d0 net/netfilter/nfnetlink.c:302
 netlink_rcv_skb+0x123/0x220 net/netlink/af_netlink.c:2550
 nfnetlink_rcv+0x167/0x1720 net/netfilter/nfnetlink.c:669
 netlink_unicast_kernel net/netlink/af_netlink.c:1318 [inline]
 netlink_unicast+0x5c0/0x690 net/netlink/af_netlink.c:1344
 netlink_sendmsg+0x5c8/0x6f0 net/netlink/af_netlink.c:1894
 sock_sendmsg_nosec net/socket.c:727 [inline]
 __sock_sendmsg+0x145/0x170 net/socket.c:742
 ____sys_sendmsg+0x31e/0x4a0 net/socket.c:2592
 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2646
 __sys_sendmsg net/socket.c:2678 [inline]
 __do_sys_sendmsg net/socket.c:2683 [inline]
 __se_sys_sendmsg net/socket.c:2681 [inline]
 __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2681
 x64_sys_call+0x17ba/0x3000 arch/x86/include/generated/asm/syscalls_64.h:47
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86af78f8 of 8 bytes by task 9300 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:500 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:2014 [inline]
 _prb_read_valid+0x383/0x950 kernel/printk/printk_ringbuffer.c:2171
 prb_first_valid_seq+0x35/0x70 kernel/printk/printk_ringbuffer.c:2299
 devkmsg_open+0x174/0x1b0 kernel/printk/printk.c:943
 memory_open+0xca/0xf0 drivers/char/mem.c:740
 chrdev_open+0x2eb/0x3a0 fs/char_dev.c:414
 do_dentry_open+0x54b/0xa60 fs/open.c:962
 vfs_open+0x37/0x1e0 fs/open.c:1094
 do_open fs/namei.c:4637 [inline]
 path_openat+0x1de9/0x23c0 fs/namei.c:4796
 do_filp_open+0x15d/0x280 fs/namei.c:4823
 do_sys_openat2+0xa6/0x150 fs/open.c:1430
 do_sys_open fs/open.c:1436 [inline]
 __do_sys_openat fs/open.c:1452 [inline]
 __se_sys_openat fs/open.c:1447 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1447
 x64_sys_call+0x2b07/0x3000 arch/x86/include/generated/asm/syscalls_64.h:258
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc0/0x2a0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x0000000000003157 -> 0x0000000000005157

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 9300 Comm: fido_id Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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