BUG: KCSAN: data-race in data_push_tail / number

write to 0xffffffff86dce108 of 1 bytes by task 18342 on cpu 1:
 number+0x955/0xb60 lib/vsprintf.c:556
 vsnprintf+0xb6d/0xed0 lib/vsprintf.c:2861
 vscnprintf+0x29/0x80 lib/vsprintf.c:2898
 printk_sprint kernel/printk/printk.c:2076 [inline]
 vprintk_store+0x638/0xbb0 kernel/printk/printk.c:2186
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 dump_stack_print_info+0xba/0x130 lib/dump_stack.c:57
 __dump_stack lib/dump_stack.c:87 [inline]
 dump_stack_lvl+0xca/0x122 lib/dump_stack.c:106
 dump_stack+0x11/0x1b lib/dump_stack.c:113
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail+0x23c/0x250 lib/fault-inject.c:146
 prepare_alloc_pages mm/page_alloc.c:5166 [inline]
 __alloc_pages+0x102/0x330 mm/page_alloc.c:5378
 alloc_pages_vma+0x67e/0x810 mm/mempolicy.c:2232
 shmem_alloc_page mm/shmem.c:1545 [inline]
 shmem_alloc_and_acct_page mm/shmem.c:1570 [inline]
 shmem_getpage_gfp+0x8b4/0x12c0 mm/shmem.c:1868
 shmem_getpage mm/shmem.c:149 [inline]
 shmem_write_begin+0x7e/0x100 mm/shmem.c:2437
 generic_perform_write+0x1c8/0x400 mm/filemap.c:3765
 __generic_file_write_iter+0xf7/0x2b0 mm/filemap.c:3892
 generic_file_write_iter+0x75/0x130 mm/filemap.c:3924
 call_write_iter include/linux/fs.h:2074 [inline]
 new_sync_write fs/read_write.c:503 [inline]
 vfs_write+0x7f5/0x950 fs/read_write.c:590
 ksys_pwrite64 fs/read_write.c:697 [inline]
 __do_sys_pwrite64 fs/read_write.c:707 [inline]
 __se_sys_pwrite64 fs/read_write.c:704 [inline]
 __x64_sys_pwrite64+0xf5/0x150 fs/read_write.c:704
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffffffff86dce108 of 8 bytes by task 18336 on cpu 0:
 data_make_reusable kernel/printk/printk_ringbuffer.c:587 [inline]
 data_push_tail+0x138/0x470 kernel/printk/printk_ringbuffer.c:672
 data_alloc+0xbc/0x2b0 kernel/printk/printk_ringbuffer.c:1043
 prb_reserve+0x920/0xbf0 kernel/printk/printk_ringbuffer.c:1549
 vprintk_store+0x560/0xbb0 kernel/printk/printk.c:2176
 vprintk_emit+0xac/0x3c0 kernel/printk/printk.c:2229
 vprintk_default+0x22/0x30 kernel/printk/printk.c:2256
 vprintk+0x7f/0x90 kernel/printk/printk_safe.c:50
 _printk+0x76/0x97 kernel/printk/printk.c:2266
 fat_msg+0x91/0xb9 fs/fat/misc.c:56
 fat__get_entry fs/fat/dir.c:102 [inline]
 fat_get_entry+0x567/0x620 fs/fat/dir.c:128
 fat_get_short_entry fs/fat/dir.c:873 [inline]
 fat_subdirs+0x56/0x1c0 fs/fat/dir.c:939
 fat_read_root fs/fat/inode.c:1413 [inline]
 fat_fill_super+0x25c2/0x2af0 fs/fat/inode.c:1860
 vfat_fill_super+0x2c/0x40 fs/fat/namei_vfat.c:1051
 mount_bdev+0x1e8/0x290 fs/super.c:1367
 vfat_mount+0x2d/0x40 fs/fat/namei_vfat.c:1058
 legacy_get_tree+0x70/0xc0 fs/fs_context.c:610
 vfs_get_tree+0x4a/0x1a0 fs/super.c:1497
 do_new_mount fs/namespace.c:2994 [inline]
 path_mount+0x11cf/0x1c40 fs/namespace.c:3324
 do_mount fs/namespace.c:3337 [inline]
 __do_sys_mount fs/namespace.c:3545 [inline]
 __se_sys_mount+0x24b/0x2f0 fs/namespace.c:3522
 __x64_sys_mount+0x63/0x70 fs/namespace.c:3522
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x44/0xae

value changed: 0x00000001000008e3 -> 0x203a6d6d6f432032

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 18336 Comm: syz-executor.5 Not tainted 5.17.0-rc2-syzkaller-00039-g9f7fb8de5d9b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
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