I'll test next week, but 4.19 has the same problem, how to fix that for 4.19? Huacai ------------------ Original ------------------ From: "Thomas Gleixner"<tglx@xxxxxxxxxxxxx>; Date: Thu, Feb 14, 2019 04:50 PM To: "Keith Busch"<keith.busch@xxxxxxxxx>; Cc: "Bjorn Helgaas"<helgaas@xxxxxxxxxx>; "Jens Axboe"<axboe@xxxxxxxxx>; "Sagi Grimberg"<sagi@xxxxxxxxxxx>; "linux-pci"<linux-pci@xxxxxxxxxxxxxxx>; "LKML"<linux-kernel@xxxxxxxxxxxxxxx>; "linux-nvme"<linux-nvme@xxxxxxxxxxxxxxxxxxx>; "Ming Lei"<ming.lei@xxxxxxxxxx>; "linux-block"<linux-block@xxxxxxxxxxxxxxx>; "Christoph Hellwig"<hch@xxxxxx>; "Huacai Chen"<chenhc@xxxxxxxxxx>; Subject: Re: [PATCH V3 1/5] genirq/affinity: don't mark 'affd' as const On Wed, 13 Feb 2019, Keith Busch wrote: Cc+ Huacai Chen > On Wed, Feb 13, 2019 at 10:41:55PM +0100, Thomas Gleixner wrote: > > Btw, while I have your attention. There popped up an issue recently related > > to that affinity logic. > > > > The current implementation fails when: > > > > /* > > * If there aren't any vectors left after applying the pre/post > > * vectors don't bother with assigning affinity. > > */ > > if (nvecs == affd->pre_vectors + affd->post_vectors) > > return NULL; > > > > Now the discussion arised, that in that case the affinity sets are not > > allocated and filled in for the pre/post vectors, but somehow the > > underlying device still works and later on triggers the warning in the > > blk-mq code because the MSI entries do not have affinity information > > attached. > > > > Sure, we could make that work, but there are several issues: > > > > 1) irq_create_affinity_masks() has another reason to return NULL: > > memory allocation fails. > > > > 2) Does it make sense at all. > > > > Right now the PCI allocator ignores the NULL return and proceeds without > > setting any affinities. As a consequence nothing is managed and everything > > happens to work. > > > > But that happens to work is more by chance than by design and the warning > > is bogus if this is an expected mode of operation. > > > > We should address these points in some way. > > Ah, yes, that's a mistake in the nvme driver. It is assuming IO queues are > always on managed interrupts, but that's not true if when only 1 vector > could be allocated. This should be an appropriate fix to the warning: Looks correct. Chen, can you please test that? > --- > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c > index 022ea1ee63f8..f2ccebe1c926 100644 > --- a/drivers/nvme/host/pci.c > +++ b/drivers/nvme/host/pci.c > @@ -506,7 +506,7 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set) > * affinity), so use the regular blk-mq cpu mapping > */ > map->queue_offset = qoff; > - if (i != HCTX_TYPE_POLL) > + if (i != HCTX_TYPE_POLL && dev->num_vecs > 1) > blk_mq_pci_map_queues(map, to_pci_dev(dev->dev), offset); > else > blk_mq_map_queues(map); > -- >
