linux-kernel - Re: [PATCH 09/16] iommu/iommufd: use page allocation function provided by iommu-pages.h

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Message-ID: <20231130000259.GS1312390@ziepe.ca>
Date:   Wed, 29 Nov 2023 20:02:59 -0400
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Pasha Tatashin <pasha.tatashin@...een.com>
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Subject: Re: [PATCH 09/16] iommu/iommufd: use page allocation function
 provided by iommu-pages.h

On Wed, Nov 29, 2023 at 04:59:43PM -0500, Pasha Tatashin wrote:
> On Tue, Nov 28, 2023 at 6:52 PM Jason Gunthorpe <jgg@...pe.ca> wrote:
> >
> > On Tue, Nov 28, 2023 at 08:49:31PM +0000, Pasha Tatashin wrote:
> > > Convert iommu/iommufd/* files to use the new page allocation functions
> > > provided in iommu-pages.h.
> > >
> > > Signed-off-by: Pasha Tatashin <pasha.tatashin@...een.com>
> > > ---
> > >  drivers/iommu/iommufd/iova_bitmap.c | 4 ++--
> > >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > This is a short term allocation, it should not be counted, that is why
> > it is already not using GFP_KERNEL_ACCOUNT.
> 
> I made this change for completeness. I changed all calls to
> get_free_page/alloc_page etc under driver/iommu to use the
> iommu_alloc_* variants, this also helps future developers in this area
> to use the right allocation functions.
> The accounting is implemented using cheap per-cpu counters, so should
> not affect the performance, I think it is OK to keep them here.

Except it is a mis use of an API that should only be used for page
table memory :(

Jason