On 2019/07/22 15:01, Ming Lei wrote: > On Tue, Jun 18, 2019 at 4:57 AM Bart Van Assche <bvanassche@xxxxxxx> wrote: >> >> On 6/17/19 5:19 AM, Christoph Hellwig wrote: >>> We need to limit the devices max_sectors to what the DMA mapping >>> implementation can support. If not we risk running out of swiotlb >>> buffers easily. >>> >>> Signed-off-by: Christoph Hellwig <hch@xxxxxx> >>> --- >>> drivers/scsi/scsi_lib.c | 2 ++ >>> 1 file changed, 2 insertions(+) >>> >>> diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c >>> index d333bb6b1c59..f233bfd84cd7 100644 >>> --- a/drivers/scsi/scsi_lib.c >>> +++ b/drivers/scsi/scsi_lib.c >>> @@ -1768,6 +1768,8 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q) >>> blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize); >>> } >>> >>> + shost->max_sectors = min_t(unsigned int, shost->max_sectors, >>> + dma_max_mapping_size(dev) << SECTOR_SHIFT); >>> blk_queue_max_hw_sectors(q, shost->max_sectors); >>> if (shost->unchecked_isa_dma) >>> blk_queue_bounce_limit(q, BLK_BOUNCE_ISA); >> >> Does dma_max_mapping_size() return a value in bytes? Is >> shost->max_sectors a number of sectors? If so, are you sure that "<< >> SECTOR_SHIFT" is the proper conversion? Shouldn't that be ">> >> SECTOR_SHIFT" instead? > > Now the patch has been committed, '<< SECTOR_SHIFT' needs to be fixed. > > Also the following kernel oops is triggered on qemu, and looks > device->dma_mask is NULL. Just hit the exact same problem using tcmu-runner (ZBC file handler) on bare metal (no QEMU). dev->dma_mask is NULL. No problem with real disks though. > > [ 5.826483] scsi host0: Virtio SCSI HBA > [ 5.829302] st: Version 20160209, fixed bufsize 32768, s/g segs 256 > [ 5.831042] SCSI Media Changer driver v0.25 > [ 5.832491] ================================================================== > [ 5.833332] BUG: KASAN: null-ptr-deref in > dma_direct_max_mapping_size+0x30/0x94 > [ 5.833332] Read of size 8 at addr 0000000000000000 by task kworker/u17:0/7 > [ 5.835506] nvme nvme0: pci function 0000:00:07.0 > [ 5.833332] > [ 5.833332] CPU: 2 PID: 7 Comm: kworker/u17:0 Not tainted 5.3.0-rc1 #1328 > [ 5.836999] ahci 0000:00:1f.2: version 3.0 > [ 5.833332] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), > BIOS ?-20180724_192412-buildhw-07.phx4 > [ 5.833332] Workqueue: events_unbound async_run_entry_fn > [ 5.833332] Call Trace: > [ 5.833332] dump_stack+0x6f/0x9d > [ 5.833332] ? dma_direct_max_mapping_size+0x30/0x94 > [ 5.833332] __kasan_report+0x161/0x189 > [ 5.833332] ? dma_direct_max_mapping_size+0x30/0x94 > [ 5.833332] kasan_report+0xe/0x12 > [ 5.833332] dma_direct_max_mapping_size+0x30/0x94 > [ 5.833332] __scsi_init_queue+0xd8/0x1f3 > [ 5.833332] scsi_mq_alloc_queue+0x62/0x89 > [ 5.833332] scsi_alloc_sdev+0x38c/0x479 > [ 5.833332] scsi_probe_and_add_lun+0x22d/0x1093 > [ 5.833332] ? kobject_set_name_vargs+0xa4/0xb2 > [ 5.833332] ? mutex_lock+0x88/0xc4 > [ 5.833332] ? scsi_free_host_dev+0x4a/0x4a > [ 5.833332] ? _raw_spin_lock_irqsave+0x8c/0xde > [ 5.833332] ? _raw_write_unlock_irqrestore+0x23/0x23 > [ 5.833332] ? ata_tdev_match+0x22/0x45 > [ 5.833332] ? attribute_container_add_device+0x160/0x17e > [ 5.833332] ? rpm_resume+0x26a/0x7c0 > [ 5.833332] ? kobject_get+0x12/0x43 > [ 5.833332] ? rpm_put_suppliers+0x7e/0x7e > [ 5.833332] ? _raw_spin_lock_irqsave+0x8c/0xde > [ 5.833332] ? _raw_write_unlock_irqrestore+0x23/0x23 > [ 5.833332] ? scsi_target_destroy+0x135/0x135 > [ 5.833332] __scsi_scan_target+0x14b/0x6aa > [ 5.833332] ? pvclock_clocksource_read+0xc0/0x14e > [ 5.833332] ? scsi_add_device+0x20/0x20 > [ 5.833332] ? rpm_resume+0x1ae/0x7c0 > [ 5.833332] ? rpm_put_suppliers+0x7e/0x7e > [ 5.833332] ? _raw_spin_lock_irqsave+0x8c/0xde > [ 5.833332] ? _raw_write_unlock_irqrestore+0x23/0x23 > [ 5.833332] ? pick_next_task_fair+0x976/0xa3d > [ 5.833332] ? mutex_lock+0x88/0xc4 > [ 5.833332] scsi_scan_channel+0x76/0x9e > [ 5.833332] scsi_scan_host_selected+0x131/0x176 > [ 5.833332] ? scsi_scan_host+0x241/0x241 > [ 5.833332] do_scan_async+0x27/0x219 > [ 5.833332] ? scsi_scan_host+0x241/0x241 > [ 5.833332] async_run_entry_fn+0xdc/0x23d > [ 5.833332] process_one_work+0x327/0x539 > [ 5.833332] worker_thread+0x330/0x492 > [ 5.833332] ? rescuer_thread+0x41f/0x41f > [ 5.833332] kthread+0x1c6/0x1d5 > [ 5.833332] ? kthread_park+0xd3/0xd3 > [ 5.833332] ret_from_fork+0x1f/0x30 > [ 5.833332] ================================================================== > > > > Thanks, > Ming Lei > -- Damien Le Moal Western Digital Research
