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BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff8415233d of 1 bytes by task 3090 on cpu 1:
 number+0x8ba/0xb50 lib/vsprintf.c:556
 vsnprintf+0xb6d/0xed0 lib/vsprintf.c:2863
 va_format lib/vsprintf.c:1694 [inline]
 pointer+0x47b/0x820 lib/vsprintf.c:2427
 vsnprintf+0x8a1/0xed0 lib/vsprintf.c:2801
 vscnprintf+0x29/0x80 lib/vsprintf.c:2900
 printk_sprint kernel/printk/printk.c:2012 [inline]
 vprintk_store+0x4c1/0x9c0 kernel/printk/printk.c:2115
 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
 printk+0x62/0x87 kernel/printk/printk.c:2216
 __ext4_msg+0x103/0x110 fs/ext4/super.c:917
 ext4_fill_super+0x29d2/0x7ff0 fs/ext4/super.c:4582
 mount_bdev+0x1e8/0x290 fs/super.c:1368
 ext4_mount+0x2d/0x40 fs/ext4/super.c:6638
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1498
 do_new_mount fs/namespace.c:2923 [inline]
 path_mount+0x11f2/0x1d30 fs/namespace.c:3253
 do_mount fs/namespace.c:3266 [inline]
 __do_sys_mount fs/namespace.c:3474 [inline]
 __se_sys_mount+0x23d/0x2e0 fs/namespace.c:3451
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3451
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff84152338 of 8 bytes by task 3092 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x125/0x460 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x8f0/0xbc0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x3e9/0x9c0 kernel/printk/printk.c:2105
 vprintk_emit+0xca/0x3d0 kernel/printk/printk.c:2157
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2185
 vprintk+0x15a/0x170 kernel/printk/printk_safe.c:392
 printk+0x62/0x87 kernel/printk/printk.c:2216
 dump_stack_print_info+0xba/0x130 lib/dump_stack.c:57
 __dump_stack lib/dump_stack.c:87 [inline]
 dump_stack_lvl+0xab/0x103 lib/dump_stack.c:105
 dump_stack+0x11/0x1a lib/dump_stack.c:112
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x23c/0x250 lib/fault-inject.c:146
 __should_failslab+0x81/0x90 mm/failslab.c:33
 should_failslab+0x5/0x20 mm/slab_common.c:1326
 slab_pre_alloc_hook mm/slab.h:494 [inline]
 slab_alloc mm/slab.c:3306 [inline]
 kmem_cache_alloc+0x46/0x2e0 mm/slab.c:3507
 kmem_cache_zalloc include/linux/slab.h:711 [inline]
 lsm_file_alloc security/security.c:572 [inline]
 security_file_alloc+0x30/0x190 security/security.c:1515
 __alloc_file+0x83/0x1a0 fs/file_table.c:106
 alloc_empty_file+0xcd/0x1c0 fs/file_table.c:150
 path_openat+0x6a/0x1f20 fs/namei.c:3493
 do_filp_open+0xe9/0x200 fs/namei.c:3534
 do_sys_openat2+0xa3/0x250 fs/open.c:1204
 do_sys_open fs/open.c:1220 [inline]
 __do_sys_openat fs/open.c:1236 [inline]
 __se_sys_openat fs/open.c:1231 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1231
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x3d/0x90 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x0000000100006734 -> 0x0000002820657a69

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 3092 Comm: syz-executor.2 Tainted: G        W         5.14.0-rc7-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
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