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

write to 0xffffffff86d9b130 of 8 bytes by task 2015 on cpu 1:
 data_alloc+0x205/0x2b0 kernel/printk/printk_ringbuffer.c:1071
 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_partition block/partitions/core.c:571 [inline]
 blk_add_partitions block/partitions/core.c:653 [inline]
 bdev_disk_changed+0x843/0xc20 block/partitions/core.c:695
 blkdev_get_whole block/bdev.c:679 [inline]
 blkdev_get_by_dev+0x767/0xcf0 block/bdev.c:813
 blkdev_open+0xb3/0x140 block/fops.c:503
 do_dentry_open+0x52c/0x860 fs/open.c:824
 vfs_open+0x43/0x50 fs/open.c:959
 do_open fs/namei.c:3476 [inline]
 path_openat+0x170c/0x1f30 fs/namei.c:3609
 do_filp_open+0x105/0x220 fs/namei.c:3636
 do_sys_openat2+0xb5/0x2b0 fs/open.c:1214
 do_sys_open fs/open.c:1230 [inline]
 __do_sys_openat fs/open.c:1246 [inline]
 __se_sys_openat fs/open.c:1241 [inline]
 __x64_sys_openat+0xef/0x110 fs/open.c:1241
 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 0xffffffff86d9b130 of 8 bytes by task 29182 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_realloc kernel/printk/printk_ringbuffer.c:1132 [inline]
 prb_reserve_in_last+0x757/0xbe0 kernel/printk/printk_ringbuffer.c:1421
 vprintk_store+0x486/0xbb0 kernel/printk/printk.c:2153
 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:531 [inline]
 blk_add_partition block/partitions/core.c:575 [inline]
 blk_add_partitions block/partitions/core.c:653 [inline]
 bdev_disk_changed+0x90c/0xc20 block/partitions/core.c:695
 loop_reread_partitions drivers/block/loop.c:518 [inline]
 loop_set_status+0x533/0x5d0 drivers/block/loop.c:1305
 lo_ioctl+0x835/0x1260
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:588
 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: 0x0000000100024eca -> 0x0000000100025da0

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 29182 Comm: syz-executor.0 Tainted: G        W         5.17.0-rc5-syzkaller-00235-gc47658311d60-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
truncated
loop0: p4 size 32768 extends beyond EOD, 
truncated
loop0: p5 size 1073741824 extends beyond EOD, 
truncated
loop0: p6 size 32768 extends beyond EOD, truncated
__loop_clr_fd: partition scan of loop0 failed (rc=-16)