syzbot

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BUG: KCSAN: data-race in _prb_read_valid / prb_reserve_in_last

write to 0xffffffff8687f000 of 8 bytes by task 3523 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
 disk_unlock_native_capacity block/partitions/core.c:520 [inline]
 blk_add_partition block/partitions/core.c:553 [inline]
 blk_add_partitions block/partitions/core.c:633 [inline]
 bdev_disk_changed+0x8d9/0xcb0 block/partitions/core.c:693
 blkdev_get_whole+0x1f5/0x2d0 block/bdev.c:748
 bdev_open+0x280/0x7e0 block/bdev.c:957
 blkdev_open+0x259/0x290 block/fops.c:691
 do_dentry_open+0x646/0xa20 fs/open.c:965
 vfs_open+0x37/0x1e0 fs/open.c:1095
 do_open fs/namei.c:3887 [inline]
 path_openat+0x1c5e/0x2170 fs/namei.c:4046
 do_filp_open+0x109/0x230 fs/namei.c:4073
 do_sys_openat2+0xa6/0x110 fs/open.c:1435
 do_sys_open fs/open.c:1450 [inline]
 __do_sys_openat fs/open.c:1466 [inline]
 __se_sys_openat fs/open.c:1461 [inline]
 __x64_sys_openat+0xf2/0x120 fs/open.c:1461
 x64_sys_call+0x2e9c/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:258
 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 0xffffffff8687eff8 of 16 bytes by task 2980 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
 syslog_print+0xeb/0x540 kernel/printk/printk.c:1633
 do_syslog+0x52b/0x7e0 kernel/printk/printk.c:1785
 __do_sys_syslog kernel/printk/printk.c:1877 [inline]
 __se_sys_syslog kernel/printk/printk.c:1875 [inline]
 __x64_sys_syslog+0x41/0x50 kernel/printk/printk.c:1875
 x64_sys_call+0x2f36/0x2ff0 arch/x86/include/generated/asm/syscalls_64.h:104
 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

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 UID: 0 PID: 2980 Comm: klogd Tainted: G        W           6.17.0-rc2-syzkaller-00028-gbe48bcf004f9 #0 PREEMPT(voluntary) 
Tainted: [W]=WARN
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025
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