==================================================================
BUG: KCSAN: data-race in data_push_tail / vsnprintf

write to 0xffffffff86d757df of 1 bytes by task 1440 on cpu 0:
 vsnprintf+0xe8f/0xed0
 vscnprintf+0x29/0x80 lib/vsprintf.c:2908
 printk_sprint kernel/printk/printk.c:2076 [inline]
 vprintk_store+0x4c8/0xbb0 kernel/printk/printk.c:2154
 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
 disk_unlock_native_capacity block/partitions/core.c:539 [inline]
 blk_add_partition block/partitions/core.c:579 [inline]
 blk_add_partitions block/partitions/core.c:657 [inline]
 bdev_disk_changed+0xa8b/0xe50 block/partitions/core.c:699
 blkdev_get_whole block/bdev.c:684 [inline]
 blkdev_get_by_dev+0x68a/0xc40 block/bdev.c:826
 blkdev_reread_part block/ioctl.c:103 [inline]
 blkdev_common_ioctl+0x10b0/0x1120 block/ioctl.c:513
 blkdev_ioctl+0x1a7/0x440 block/ioctl.c:591
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 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 0xffffffff86d757d8 of 8 bytes by task 14902 on cpu 1:
 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
 blk_add_partitions block/partitions/core.c:646 [inline]
 bdev_disk_changed+0xc8c/0xe50 block/partitions/core.c:699
 loop_reread_partitions drivers/block/loop.c:517 [inline]
 loop_set_status+0x535/0x5d0 drivers/block/loop.c:1310
 lo_ioctl+0x785/0x1270
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:597
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:874 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:860
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:860
 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: 0x0000000100014c91 -> 0x000a646564657461

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 14902 Comm: syz-executor.5 Not tainted 5.15.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
truncated
loop5: p1 start 335762607 is beyond EOD, truncated
loop5: p2 size 2424832 extends beyond EOD, truncated
loop5: p4 size 2097152 extends beyond EOD, truncated