On 4/17/21 8:29 AM, Jens Axboe wrote: > There's currently no way to experiment with polled IO with null_blk, > which seems like an oversight. This patch adds support for polled IO. > We keep a list of issued IOs on submit, and then process that list > when mq_ops->poll() is invoked. > > A new parameter is added, poll_queues. It defaults to 1 like the > submit queues, meaning we'll have 1 poll queue available. Has anyone run blktests against blk-for-next since this patch got queued? The following appears in the kernel log if I run blktests: root[5563]: run blktests block/010 null_blk: module loaded ================================================================== BUG: KASAN: null-ptr-deref in null_map_queues+0x131/0x1a0 [null_blk] Read of size 8 at addr 0000000000000000 by task modprobe/5612 CPU: 7 PID: 5612 Comm: modprobe Not tainted 5.12.0-dbg+ #33 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a-rebuilt.opensuse.org 04/01/2014 Call Trace: show_stack+0x52/0x58 dump_stack+0x9d/0xcf kasan_report.cold+0x4b/0x50 __asan_load8+0x69/0x90 null_map_queues+0x131/0x1a0 [null_blk] blk_mq_update_queue_map+0x122/0x1a0 blk_mq_alloc_tag_set+0x1c8/0x480 null_init_tag_set+0x19c/0x220 [null_blk] null_init+0x1ac/0x1000 [null_blk] do_one_initcall+0xd3/0x460 do_init_module+0x10a/0x400 load_module+0xbe2/0xc50 __do_sys_finit_module+0x131/0x1c0 __x64_sys_finit_module+0x43/0x50 do_syscall_64+0x3a/0xb0 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x7f51f7fd367d Code: 00 c3 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 8b 0d bb f7 0c 00 f7 d8 64 89 01 48 RSP: 002b:00007ffd4a668728 EFLAGS: 00000246 ORIG_RAX: 0000000000000139 RAX: ffffffffffffffda RBX: 00005609718ddbe0 RCX: 00007f51f7fd367d RDX: 0000000000000000 RSI: 00005609718ddfe0 RDI: 0000000000000003 RBP: 0000000000040000 R08: 0000000000000000 R09: 000000000000003a R10: 0000000000000003 R11: 0000000000000246 R12: 00005609718ddfe0 R13: 0000000000000000 R14: 00005609718ddd70 R15: 00005609718ddbe0 ================================================================== Thanks, Bart.
