Nouveau - Jan 2023 - [PATCH 6/8] iommu/intel: Add a gfp parameter to alloc_pgtable_page()

On Tue, Jan 17, 2023 at 03:35:08AM +0000, Tian, Kevin
wrote:
> > From: Jason Gunthorpe <jgg at nvidia.com>
> > Sent: Saturday, January 7, 2023 12:43 AM
> > 
> > @@ -2676,7 +2676,7 @@ static int copy_context_table(struct intel_iommu
> > *iommu,
> >  			if (!old_ce)
> >  				goto out;
> > 
> > -			new_ce = alloc_pgtable_page(iommu->node);
> > +			new_ce = alloc_pgtable_page(iommu->node,
> > GFP_KERNEL);
> 
> GFP_ATOMIC
Can't be:

			old_ce = memremap(old_ce_phys, PAGE_SIZE,
					MEMREMAP_WB);
			if (!old_ce)
				goto out;

			new_ce = alloc_pgtable_page(iommu->node, GFP_KERNEL);
			if (!new_ce)

memremap() is sleeping.

And the only caller is:

	ctxt_tbls = kcalloc(ctxt_table_entries, sizeof(void *), GFP_KERNEL);
	if (!ctxt_tbls)
		goto out_unmap;

	for (bus = 0; bus < 256; bus++) {
		ret = copy_context_table(iommu, &old_rt[bus],
					 ctxt_tbls, bus, ext);

Jason

> From: Jason Gunthorpe <jgg at nvidia.com>
> Sent: Tuesday, January 17, 2023 9:30 PM
> 
> On Tue, Jan 17, 2023 at 03:35:08AM +0000, Tian, Kevin wrote:
> > > From: Jason Gunthorpe <jgg at nvidia.com>
> > > Sent: Saturday, January 7, 2023 12:43 AM
> > >
> > > @@ -2676,7 +2676,7 @@ static int copy_context_table(struct
> intel_iommu
> > > *iommu,
> > >  			if (!old_ce)
> > >  				goto out;
> > >
> > > -			new_ce = alloc_pgtable_page(iommu->node);
> > > +			new_ce = alloc_pgtable_page(iommu->node,
> > > GFP_KERNEL);
> >
> > GFP_ATOMIC
> 
> Can't be:
> 
> 			old_ce = memremap(old_ce_phys, PAGE_SIZE,
> 					MEMREMAP_WB);
> 			if (!old_ce)
> 				goto out;
> 
> 			new_ce = alloc_pgtable_page(iommu->node,
> GFP_KERNEL);
> 			if (!new_ce)
> 
> memremap() is sleeping.
> 
> And the only caller is:
> 
> 	ctxt_tbls = kcalloc(ctxt_table_entries, sizeof(void *), GFP_KERNEL);
> 	if (!ctxt_tbls)
> 		goto out_unmap;
> 
> 	for (bus = 0; bus < 256; bus++) {
> 		ret = copy_context_table(iommu, &old_rt[bus],
> 					 ctxt_tbls, bus, ext);
> 
Yes, but the patch description says "Push the GFP_ATOMIC to all
callers." implying it's purely a refactoring w/o changing those
semantics.

I'm fine with doing this change in this patch, but it should worth
a clarification in the patch description.

On Wed, Jan 18, 2023 at 01:18:18AM +0000, Tian, Kevin
wrote:
> > From: Jason Gunthorpe <jgg at nvidia.com>
> > Sent: Tuesday, January 17, 2023 9:30 PM
> > 
> > On Tue, Jan 17, 2023 at 03:35:08AM +0000, Tian, Kevin wrote:
> > > > From: Jason Gunthorpe <jgg at nvidia.com>
> > > > Sent: Saturday, January 7, 2023 12:43 AM
> > > >
> > > > @@ -2676,7 +2676,7 @@ static int copy_context_table(struct
> > intel_iommu
> > > > *iommu,
> > > >  			if (!old_ce)
> > > >  				goto out;
> > > >
> > > > -			new_ce = alloc_pgtable_page(iommu->node);
> > > > +			new_ce = alloc_pgtable_page(iommu->node,
> > > > GFP_KERNEL);
> > >
> > > GFP_ATOMIC
> > 
> > Can't be:
> > 
> > 			old_ce = memremap(old_ce_phys, PAGE_SIZE,
> > 					MEMREMAP_WB);
> > 			if (!old_ce)
> > 				goto out;
> > 
> > 			new_ce = alloc_pgtable_page(iommu->node,
> > GFP_KERNEL);
> > 			if (!new_ce)
> > 
> > memremap() is sleeping.
> > 
> > And the only caller is:
> > 
> > 	ctxt_tbls = kcalloc(ctxt_table_entries, sizeof(void *), GFP_KERNEL);
> > 	if (!ctxt_tbls)
> > 		goto out_unmap;
> > 
> > 	for (bus = 0; bus < 256; bus++) {
> > 		ret = copy_context_table(iommu, &old_rt[bus],
> > 					 ctxt_tbls, bus, ext);
> > 
> 
> Yes, but the patch description says "Push the GFP_ATOMIC to all
> callers." implying it's purely a refactoring w/o changing those
> semantics.
Sure, lets split the patch, it is a good idea

Jason