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BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86065c60 of 8 bytes by task 24421 on cpu 1:
 data_alloc+0x291/0x2c0 kernel/printk/printk_ringbuffer.c:1096
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2269
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2329
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2373
 selinux_add_opt+0x22d/0x280 security/selinux/hooks.c:1043
 selinux_sb_eat_lsm_opts+0x6c5/0x780 security/selinux/hooks.c:2619
 security_sb_eat_lsm_opts+0x42/0x70 security/security.c:1361
 shmem_parse_options+0x28/0x160 mm/shmem.c:4113
 parse_monolithic_mount_data+0x43/0x50 fs/fs_context.c:719
 do_new_mount+0x1fa/0x690 fs/namespace.c:3348
 path_mount+0x49b/0xb30 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3875
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3875
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

read to 0xffffffff86065c60 of 8 bytes by task 24422 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:778 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:924 [inline]
 prb_reserve+0x235/0xb60 kernel/printk/printk_ringbuffer.c:1619
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2269
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2329
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2373
 selinux_add_opt+0x22d/0x280 security/selinux/hooks.c:1043
 selinux_sb_eat_lsm_opts+0x6c5/0x780 security/selinux/hooks.c:2619
 security_sb_eat_lsm_opts+0x42/0x70 security/security.c:1361
 shmem_parse_options+0x28/0x160 mm/shmem.c:4113
 parse_monolithic_mount_data+0x43/0x50 fs/fs_context.c:719
 do_new_mount+0x1fa/0x690 fs/namespace.c:3348
 path_mount+0x49b/0xb30 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount+0x27f/0x2d0 fs/namespace.c:3875
 __x64_sys_mount+0x67/0x80 fs/namespace.c:3875
 do_syscall_64+0xd3/0x1d0
 entry_SYSCALL_64_after_hwframe+0x72/0x7a

value changed: 0x0000000000078ee0 -> 0x0000000000126098

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 24422 Comm: syz-executor.3 Tainted: G        W          6.9.0-rc2-syzkaller-00002-g026e680b0a08 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
==================================================================
SELinux: security_context_str_to_sid (unconfined_u) failed with errno=-22