syzbot

loop7: detected capacity change from 0 to 1036
==================================================================
BUG: KCSAN: data-race in lo_ioctl / loop_queue_rq

write to 0xffff88810091e110 of 4 bytes by task 9653 on cpu 0:
 loop_clr_fd drivers/block/loop.c:1333 [inline]
 lo_ioctl+0x9ce/0x11f0 drivers/block/loop.c:1694
 blkdev_ioctl+0x1d0/0x3c0 block/ioctl.c:585
 block_ioctl+0x6d/0x80 fs/block_dev.c:1671
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl+0xcb/0x140 fs/ioctl.c:739
 __x64_sys_ioctl+0x3f/0x50 fs/ioctl.c:739
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

read to 0xffff88810091e110 of 4 bytes by task 9632 on cpu 1:
 loop_queue_rq+0x47/0x120 drivers/block/loop.c:2006
 blk_mq_dispatch_rq_list+0x5b0/0xfa0 block/blk-mq.c:1369
 __blk_mq_do_dispatch_sched block/blk-mq-sched.c:186 [inline]
 blk_mq_do_dispatch_sched+0x370/0x610 block/blk-mq-sched.c:199
 __blk_mq_sched_dispatch_requests+0x21e/0x2c0 block/blk-mq-sched.c:310
 blk_mq_sched_dispatch_requests+0x9f/0x110 block/blk-mq-sched.c:341
 __blk_mq_run_hw_queue+0xbc/0x140 block/blk-mq.c:1488
 __blk_mq_delay_run_hw_queue+0x163/0x2d0 block/blk-mq.c:1565
 blk_mq_run_hw_queue+0x22c/0x250 block/blk-mq.c:1618
 blk_mq_sched_insert_requests+0x13f/0x200 block/blk-mq-sched.c:491
 blk_mq_flush_plug_list+0x2f5/0x3c0 block/blk-mq.c:1942
 blk_flush_plug_list+0x235/0x260 block/blk-core.c:1749
 blk_finish_plug+0x44/0x60 block/blk-core.c:1766
 read_pages+0x2d9/0x530 mm/readahead.c:150
 page_cache_ra_unbounded+0x3a8/0x400 mm/readahead.c:238
 ondemand_readahead+0x56f/0x7a0 mm/readahead.c:267
 page_cache_async_ra+0x16e/0x190 mm/readahead.c:607
 page_cache_async_readahead include/linux/pagemap.h:863 [inline]
 filemap_readahead mm/filemap.c:2356 [inline]
 filemap_get_pages mm/filemap.c:2397 [inline]
 filemap_read+0x485/0x1210 mm/filemap.c:2464
 generic_file_read_iter+0x84/0x3e0 mm/filemap.c:2615
 blkdev_read_iter+0xb3/0xc0 fs/block_dev.c:1727
 call_read_iter include/linux/fs.h:1971 [inline]
 generic_file_splice_read+0x22a/0x310 fs/splice.c:311
 do_splice_to fs/splice.c:796 [inline]
 splice_direct_to_actor+0x2aa/0x650 fs/splice.c:870
 do_splice_direct+0xf5/0x170 fs/splice.c:979
 do_sendfile+0x773/0xda0 fs/read_write.c:1260
 __do_sys_sendfile64 fs/read_write.c:1325 [inline]
 __se_sys_sendfile64 fs/read_write.c:1311 [inline]
 __x64_sys_sendfile64+0xf2/0x130 fs/read_write.c:1311
 do_syscall_64+0x34/0x50 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xae

Reported by Kernel Concurrency Sanitizer on:
CPU: 1 PID: 9632 Comm: syz-executor.3 Not tainted 5.12.0-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
==================================================================
blk_update_request: I/O error, dev loop7, sector 808 op 0x0:(READ) flags 0x80700 phys_seg 29 prio class 0
blk_update_request: I/O error, dev loop7, sector 560 op 0x0:(READ) flags 0x80700 phys_seg 30 prio class 0