syzbot

==================================================================
BUG: KCSAN: data-race in loop_configure / loop_queue_rq

write to 0xffff888101f01678 of 4 bytes by task 25767 on cpu 0:
 loop_configure+0xb28/0xc30 drivers/block/loop.c:1105
 lo_ioctl+0x641/0x1290
 blkdev_ioctl+0x20e/0x440 block/ioctl.c:614
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:856
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

read to 0xffff888101f01678 of 4 bytes by task 22320 on cpu 1:
 loop_queue_rq+0x4b/0x650 drivers/block/loop.c:1811
 __blk_mq_issue_directly+0x66/0x410 block/blk-mq.c:2440
 __blk_mq_try_issue_directly+0x25d/0x2c0 block/blk-mq.c:2493
 blk_mq_request_issue_directly block/blk-mq.c:2527 [inline]
 blk_mq_plug_issue_direct+0x15d/0x5c0 block/blk-mq.c:2547
 blk_mq_flush_plug_list+0x27a/0x340 block/blk-mq.c:2639
 __blk_flush_plug+0x25a/0x2b0 block/blk-core.c:1153
 blk_finish_plug+0x44/0x60 block/blk-core.c:1177
 read_pages+0x71c/0x790 mm/readahead.c:181
 page_cache_ra_unbounded+0x2a8/0x2e0 mm/readahead.c:263
 do_page_cache_ra mm/readahead.c:293 [inline]
 force_page_cache_ra+0x1c6/0x200 mm/readahead.c:324
 page_cache_sync_ra+0xc8/0xf0 mm/readahead.c:695
 page_cache_sync_readahead include/linux/pagemap.h:1215 [inline]
 filemap_get_pages mm/filemap.c:2566 [inline]
 filemap_read+0x3ef/0x1430 mm/filemap.c:2660
 blkdev_read_iter+0x2c6/0x370 block/fops.c:598
 call_read_iter include/linux/fs.h:2181 [inline]
 new_sync_read fs/read_write.c:389 [inline]
 vfs_read+0x3a5/0x560 fs/read_write.c:470
 ksys_read+0xe8/0x1a0 fs/read_write.c:607
 __do_sys_read fs/read_write.c:617 [inline]
 __se_sys_read fs/read_write.c:615 [inline]
 __x64_sys_read+0x3e/0x50 fs/read_write.c:615
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0x00000000 -> 0x00000001

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 22320 Comm: udevd Not tainted 6.0.0-rc7-syzkaller-00042-g46452d3786a8-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
==================================================================
I/O error, dev loop0, sector 3968 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 2