syzbot

loop7: detected capacity change from 0 to 16384
==================================================================
BUG: KCSAN: data-race in lo_ioctl / loop_queue_rq

write to 0xffff8881001f7280 of 4 bytes by task 10703 on cpu 1:
 loop_clr_fd drivers/block/loop.c:1261 [inline]
 lo_ioctl+0xa5c/0x1570 drivers/block/loop.c:1571
 blkdev_ioctl+0x35b/0x450 block/ioctl.c:698
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:906 [inline]
 __se_sys_ioctl+0xc9/0x140 fs/ioctl.c:892
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:892
 x64_sys_call+0x168d/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffff8881001f7280 of 4 bytes by task 10690 on cpu 0:
 loop_queue_rq+0x50/0x670 drivers/block/loop.c:1881
 __blk_mq_issue_directly block/blk-mq.c:2691 [inline]
 blk_mq_request_issue_directly+0x1dc/0x390 block/blk-mq.c:2778
 blk_mq_plug_issue_direct+0x1ad/0x570 block/blk-mq.c:2799
 blk_mq_flush_plug_list+0x2bd/0xf10 block/blk-mq.c:2910
 __blk_flush_plug+0x21f/0x2a0 block/blk-core.c:1220
 blk_finish_plug+0x48/0x70 block/blk-core.c:1247
 read_pages+0x3ee/0x470 mm/readahead.c:173
 page_cache_ra_unbounded+0x30d/0x350 mm/readahead.c:297
 do_page_cache_ra mm/readahead.c:327 [inline]
 page_cache_ra_order mm/readahead.c:532 [inline]
 page_cache_async_ra+0x41d/0x450 mm/readahead.c:687
 filemap_readahead mm/filemap.c:2559 [inline]
 filemap_get_pages+0x512/0x11b0 mm/filemap.c:2604
 filemap_splice_read+0x35a/0x930 mm/filemap.c:2980
 do_splice_read fs/splice.c:979 [inline]
 splice_direct_to_actor+0x26c/0x680 fs/splice.c:1083
 do_splice_direct_actor fs/splice.c:1201 [inline]
 do_splice_direct+0xd9/0x150 fs/splice.c:1227
 do_sendfile+0x40a/0x690 fs/read_write.c:1368
 __do_sys_sendfile64 fs/read_write.c:1429 [inline]
 __se_sys_sendfile64 fs/read_write.c:1415 [inline]
 __x64_sys_sendfile64+0x113/0x160 fs/read_write.c:1415
 x64_sys_call+0xfc3/0x2e10 arch/x86/include/generated/asm/syscalls_64.h:41
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000001 -> 0x00000002

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 10690 Comm: syz.4.1722 Not tainted 6.15.0-rc1-syzkaller-00246-g900241a5cc15 #0 PREEMPT(voluntary) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2025
==================================================================
blk_print_req_error: 54 callbacks suppressed
I/O error, dev loop7, sector 3584 op 0x0:(READ) flags 0x80700 phys_seg 32 prio class 0
I/O error, dev loop7, sector 3336 op 0x0:(READ) flags 0x80700 phys_seg 31 prio class 0
I/O error, dev loop7, sector 3336 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0
I/O error, dev loop7, sector 3336 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0