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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve

write to 0xffffffff868fa728 of 88 bytes by task 27335 on cpu 0:
 prb_reserve+0x695/0xaf0 kernel/printk/printk_ringbuffer.c:1651
 vprintk_store+0x56d/0x860 kernel/printk/printk.c:2299
 vprintk_emit+0x10d/0x580 kernel/printk/printk.c:2399
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2438
 vprintk+0x1d/0x30 kernel/printk/printk_safe.c:82
 _printk+0x79/0xa0 kernel/printk/printk.c:2448
 ib_get_eth_speed+0x33d/0x4b0 drivers/infiniband/core/verbs.c:2006
 siw_query_port+0x3a/0x2d0 drivers/infiniband/sw/siw/siw_verbs.c:179
 iw_query_port drivers/infiniband/core/device.c:2137 [inline]
 ib_query_port+0x393/0x3d0 drivers/infiniband/core/device.c:2178
 ib_setup_port_attrs+0x14a/0x1430 drivers/infiniband/core/sysfs.c:1429
 add_one_compat_dev+0x261/0x360 drivers/infiniband/core/device.c:1005
 rdma_dev_init_net+0x182/0x210 drivers/infiniband/core/device.c:1221
 ops_init+0x22a/0x2e0 net/core/net_namespace.c:137
 setup_net+0x83/0x210 net/core/net_namespace.c:445
 copy_net_ns+0x28c/0x3b0 net/core/net_namespace.c:580
 create_new_namespaces+0x20e/0x3d0 kernel/nsproxy.c:110
 copy_namespaces+0x1ad/0x210 kernel/nsproxy.c:175
 copy_process+0xd32/0x2000 kernel/fork.c:2184
 kernel_clone+0x16c/0x5c0 kernel/fork.c:2609
 __do_sys_clone kernel/fork.c:2750 [inline]
 __se_sys_clone kernel/fork.c:2734 [inline]
 __x64_sys_clone+0xe6/0x120 kernel/fork.c:2734
 x64_sys_call+0x119c/0x3000 arch/x86/include/generated/asm/syscalls_64.h:57
 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 0xffffffff868fa728 of 8 bytes by task 27311 on cpu 1:
 desc_read kernel/printk/printk_ringbuffer.c:483 [inline]
 prb_first_seq kernel/printk/printk_ringbuffer.c:1975 [inline]
 _prb_read_valid+0x383/0x920 kernel/printk/printk_ringbuffer.c:2132
 prb_read_valid+0x3c/0x60 kernel/printk/printk_ringbuffer.c:2203
 printk_get_next_message+0xc8/0x510 kernel/printk/printk.c:2978
 console_emit_next_record kernel/printk/printk.c:3065 [inline]
 console_flush_all+0x290/0x6a0 kernel/printk/printk.c:3199
 __console_flush_and_unlock kernel/printk/printk.c:3258 [inline]
 console_unlock+0xa1/0x2e0 kernel/printk/printk.c:3298
 class_console_lock_destructor include/linux/console.h:669 [inline]
 do_con_write+0x28df/0x2940 drivers/tty/vt/vt.c:3243
 con_write+0x24/0x40 drivers/tty/vt/vt.c:3565
 process_output_block drivers/tty/n_tty.c:561 [inline]
 n_tty_write+0x7ca/0xb40 drivers/tty/n_tty.c:2377
 iterate_tty_write drivers/tty/tty_io.c:1006 [inline]
 file_tty_write+0x378/0x690 drivers/tty/tty_io.c:1081
 tty_write+0x25/0x30 drivers/tty/tty_io.c:1102
 new_sync_write fs/read_write.c:593 [inline]
 vfs_write+0x52a/0x960 fs/read_write.c:686
 ksys_write+0xda/0x1a0 fs/read_write.c:738
 __do_sys_write fs/read_write.c:749 [inline]
 __se_sys_write fs/read_write.c:746 [inline]
 __x64_sys_write+0x40/0x50 fs/read_write.c:746
 x64_sys_call+0x2802/0x3000 arch/x86/include/generated/asm/syscalls_64.h:2
 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

value changed: 0x00000000000031dd -> 0x00000000000051dd

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 27311 Comm: syz.5.6675 Tainted: G        W           syzkaller #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
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