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

write to 0xffffffff8710f580 of 1 bytes by task 3094 on cpu 0:
 string_nocheck lib/vsprintf.c:650 [inline]
 string+0x16c/0x200 lib/vsprintf.c:728
 vsnprintf+0xa09/0xe30 lib/vsprintf.c:2824
 vscnprintf+0x42/0x80 lib/vsprintf.c:2930
 printk_sprint+0x30/0x2d0 kernel/printk/printk.c:2124
 vprintk_store+0x56f/0x800 kernel/printk/printk.c:2238
 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2284
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 __loop_clr_fd+0x39b/0x3a0 drivers/block/loop.c:1189
 loop_clr_fd drivers/block/loop.c:1253 [inline]
 lo_ioctl+0xe93/0x12e0 drivers/block/loop.c:1557
 blkdev_ioctl+0x375/0x460 block/ioctl.c:634
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:871 [inline]
 __se_sys_ioctl+0xcf/0x140 fs/ioctl.c:857
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:857
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

read to 0xffffffff8710f580 of 8 bytes by task 8249 on cpu 1:
 data_make_reusable kernel/printk/printk_ringbuffer.c:590 [inline]
 data_push_tail+0x102/0x430 kernel/printk/printk_ringbuffer.c:675
 data_alloc+0xbe/0x2c0 kernel/printk/printk_ringbuffer.c:1046
 prb_reserve+0x897/0xbc0 kernel/printk/printk_ringbuffer.c:1555
 vprintk_store+0x53e/0x800 kernel/printk/printk.c:2228
 vprintk_emit+0xd0/0x5d0 kernel/printk/printk.c:2284
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2318
 vprintk+0x71/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2328
 blk_print_req_error+0x10a/0x120 block/blk-mq.c:808
 blk_update_request+0x849/0x950 block/blk-mq.c:921
 blk_mq_end_request block/blk-mq.c:1060 [inline]
 blk_mq_plug_issue_direct+0x195/0x520 block/blk-mq.c:2728
 blk_mq_flush_plug_list+0x2a7/0xdc0 block/blk-mq.c:2826
 __blk_flush_plug+0x210/0x260 block/blk-core.c:1176
 blk_finish_plug+0x47/0x60 block/blk-core.c:1200
 read_pages+0x4bf/0x540 mm/readahead.c:183
 page_cache_ra_unbounded+0x2aa/0x2e0 mm/readahead.c:269
 do_page_cache_ra mm/readahead.c:299 [inline]
 force_page_cache_ra mm/readahead.c:330 [inline]
 page_cache_sync_ra+0x24b/0x2a0 mm/readahead.c:689
 page_cache_sync_readahead include/linux/pagemap.h:1300 [inline]
 filemap_get_pages+0x251/0xf90 mm/filemap.c:2498
 filemap_read+0x214/0x680 mm/filemap.c:2594
 blkdev_read_iter+0x217/0x2c0 block/fops.c:757
 call_read_iter include/linux/fs.h:2081 [inline]
 new_sync_read fs/read_write.c:395 [inline]
 vfs_read+0x5ab/0x6a0 fs/read_write.c:476
 ksys_read+0xeb/0x1a0 fs/read_write.c:619
 __do_sys_read fs/read_write.c:629 [inline]
 __se_sys_read fs/read_write.c:627 [inline]
 __x64_sys_read+0x42/0x50 fs/read_write.c:627
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xcd/0x1d0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x63/0x6b

value changed: 0x00000001000024e8 -> 0x3a64665f726c635f

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 8249 Comm: udevd Not tainted 6.8.0-rc5-syzkaller-00121-g1c892cdd8fe0 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/25/2024
==================================================================
I/O error, dev loop0, sector 20 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
I/O error, dev loop0, sector 20 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
I/O error, dev loop0, sector 20 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
udevd[8249]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory
udevd[8249]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory
udevd[8249]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory
udevd[8249]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory
udevd[8249]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory
udevd[8249]: inotify_add_watch(7, /dev/loop0p3, 10) failed: No such file or directory