From: Jason Gunthorpe <jgg@ziepe.ca>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-mm@kvack.org, "Ralph Campbell" <rcampbell@nvidia.com>,
"Alex Deucher" <alexander.deucher@amd.com>,
amd-gfx@lists.freedesktop.org, "Ben Skeggs" <bskeggs@redhat.com>,
"Christian König" <christian.koenig@amd.com>,
"David (ChunMing) Zhou" <David1.Zhou@amd.com>,
dri-devel@lists.freedesktop.org, "Kuehling,
Felix" <Felix.Kuehling@amd.com>,
intel-gfx@lists.freedesktop.org,
"Jérôme Glisse" <jglisse@redhat.com>,
"John Hubbard" <jhubbard@nvidia.com>,
linux-kernel@vger.kernel.org,
"Niranjana Vishwanathapura" <niranjana.vishwanathapura@intel.com>,
nouveau@lists.freedesktop.org
Subject: Re: [PATCH hmm 2/5] mm/hmm: make hmm_range_fault return 0 or -1
Date: Wed, 29 Apr 2020 16:38:49 -0300 [thread overview]
Message-ID: <20200429193849.GA3824@ziepe.ca> (raw)
In-Reply-To: <20200422055229.GB22366@lst.de>
On Wed, Apr 22, 2020 at 07:52:29AM +0200, Christoph Hellwig wrote:
> On Tue, Apr 21, 2020 at 09:21:43PM -0300, Jason Gunthorpe wrote:
> > From: Jason Gunthorpe <jgg@mellanox.com>
> >
> > hmm_vma_walk->last is supposed to be updated after every write to the
> > pfns, so that it can be returned by hmm_range_fault(). However, this is
> > not done consistently. Fortunately nothing checks the return code of
> > hmm_range_fault() for anything other than error.
> >
> > More importantly last must be set before returning -EBUSY as it is used to
> > prevent reading an output pfn as an input flags when the loop restarts.
> >
> > For clarity and simplicity make hmm_range_fault() return 0 or -ERRNO. Only
> > set last when returning -EBUSY.
> >
> > Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
> > Documentation/vm/hmm.rst | 2 +-
> > drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 4 ++--
> > drivers/gpu/drm/nouveau/nouveau_svm.c | 6 +++---
> > include/linux/hmm.h | 2 +-
> > mm/hmm.c | 25 +++++++++----------------
> > 5 files changed, 16 insertions(+), 23 deletions(-)
> >
> > diff --git a/Documentation/vm/hmm.rst b/Documentation/vm/hmm.rst
> > index 4e3e9362afeb10..9924f2caa0184c 100644
> > +++ b/Documentation/vm/hmm.rst
> > @@ -161,7 +161,7 @@ device must complete the update before the driver callback returns.
> > When the device driver wants to populate a range of virtual addresses, it can
> > use::
> >
> > - long hmm_range_fault(struct hmm_range *range);
> > + int hmm_range_fault(struct hmm_range *range);
> >
> > It will trigger a page fault on missing or read-only entries if write access is
> > requested (see below). Page faults use the generic mm page fault code path just
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > index 6309ff72bd7876..efc1329a019127 100644
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
> > @@ -852,12 +852,12 @@ int amdgpu_ttm_tt_get_user_pages(struct amdgpu_bo *bo, struct page **pages)
> > down_read(&mm->mmap_sem);
> > r = hmm_range_fault(range);
> > up_read(&mm->mmap_sem);
> > - if (unlikely(r <= 0)) {
> > + if (unlikely(r)) {
> > /*
> > * FIXME: This timeout should encompass the retry from
> > * mmu_interval_read_retry() as well.
> > */
> > - if ((r == 0 || r == -EBUSY) && !time_after(jiffies, timeout))
> > + if ((r == -EBUSY) && !time_after(jiffies, timeout))
>
> Please also kill the superflous inner braces here.
>
> > + * Return: 0 or -ERRNO with one of the following status codes:
>
> Maybe say something like:
>
> * Returns 0 on success or one of the following error codes:
>
> Otherwise this looks good:
Got it, thanks
Jason
next prev parent reply other threads:[~2020-04-29 19:38 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-22 0:21 [PATCH hmm 0/5] Adjust hmm_range_fault() API Jason Gunthorpe
2020-04-22 0:21 ` [PATCH hmm 1/5] mm/hmm: make CONFIG_DEVICE_PRIVATE into a select Jason Gunthorpe
2020-04-22 5:50 ` Christoph Hellwig
2020-04-22 0:21 ` [PATCH hmm 2/5] mm/hmm: make hmm_range_fault return 0 or -1 Jason Gunthorpe
2020-04-22 5:52 ` Christoph Hellwig
2020-04-29 19:38 ` Jason Gunthorpe [this message]
2020-04-22 0:21 ` [PATCH hmm 3/5] drm/amdgpu: remove dead code after hmm_range_fault() Jason Gunthorpe
2020-04-22 0:21 ` [PATCH hmm 4/5] mm/hmm: remove HMM_PFN_SPECIAL Jason Gunthorpe
2020-04-22 5:53 ` Christoph Hellwig
2020-04-22 0:21 ` [PATCH hmm 5/5] mm/hmm: remove the customizable pfn format from hmm_range_fault Jason Gunthorpe
2020-04-22 6:03 ` Christoph Hellwig
2020-04-22 12:39 ` Jason Gunthorpe
2020-04-23 6:10 ` Christoph Hellwig
2020-04-22 17:52 ` Felix Kuehling
2020-04-29 22:41 ` Jason Gunthorpe
2020-04-22 19:09 ` [PATCH hmm 0/5] Adjust hmm_range_fault() API Ralph Campbell
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200429193849.GA3824@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=David1.Zhou@amd.com \
--cc=Felix.Kuehling@amd.com \
--cc=alexander.deucher@amd.com \
--cc=amd-gfx@lists.freedesktop.org \
--cc=bskeggs@redhat.com \
--cc=christian.koenig@amd.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=hch@lst.de \
--cc=intel-gfx@lists.freedesktop.org \
--cc=jglisse@redhat.com \
--cc=jhubbard@nvidia.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=niranjana.vishwanathapura@intel.com \
--cc=nouveau@lists.freedesktop.org \
--cc=rcampbell@nvidia.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).