From: Jason Gunthorpe <jgg@mellanox.com>
To: Jerome Glisse <jglisse@redhat.com>
Cc: Dan Williams <dan.j.williams@intel.com>,
Christoph Hellwig <hch@lst.de>, Ben Skeggs <bskeggs@redhat.com>,
Felix Kuehling <Felix.Kuehling@amd.com>,
Ralph Campbell <rcampbell@nvidia.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"nouveau@lists.freedesktop.org" <nouveau@lists.freedesktop.org>,
"dri-devel@lists.freedesktop.org"
<dri-devel@lists.freedesktop.org>,
"amd-gfx@lists.freedesktop.org" <amd-gfx@lists.freedesktop.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 04/15] mm: remove the pgmap field from struct hmm_vma_walk
Date: Thu, 15 Aug 2019 19:22:02 +0000 [thread overview]
Message-ID: <20190815192157.GB22970@mellanox.com> (raw)
In-Reply-To: <20190815180325.GA4920@redhat.com>
On Thu, Aug 15, 2019 at 02:03:25PM -0400, Jerome Glisse wrote:
> On Wed, Aug 14, 2019 at 07:48:28AM -0700, Dan Williams wrote:
> > On Wed, Aug 14, 2019 at 6:28 AM Jason Gunthorpe <jgg@mellanox.com> wrote:
> > >
> > > On Wed, Aug 14, 2019 at 09:38:54AM +0200, Christoph Hellwig wrote:
> > > > On Tue, Aug 13, 2019 at 06:36:33PM -0700, Dan Williams wrote:
> > > > > Section alignment constraints somewhat save us here. The only example
> > > > > I can think of a PMD not containing a uniform pgmap association for
> > > > > each pte is the case when the pgmap overlaps normal dram, i.e. shares
> > > > > the same 'struct memory_section' for a given span. Otherwise, distinct
> > > > > pgmaps arrange to manage their own exclusive sections (and now
> > > > > subsections as of v5.3). Otherwise the implementation could not
> > > > > guarantee different mapping lifetimes.
> > > > >
> > > > > That said, this seems to want a better mechanism to determine "pfn is
> > > > > ZONE_DEVICE".
> > > >
> > > > So I guess this patch is fine for now, and once you provide a better
> > > > mechanism we can switch over to it?
> > >
> > > What about the version I sent to just get rid of all the strange
> > > put_dev_pagemaps while scanning? Odds are good we will work with only
> > > a single pagemap, so it makes some sense to cache it once we find it?
> >
> > Yes, if the scan is over a single pmd then caching it makes sense.
>
> Quite frankly an easier an better solution is to remove the pagemap
> lookup as HMM user abide by mmu notifier it means we will not make
> use or dereference the struct page so that we are safe from any
> racing hotunplug of dax memory (as long as device driver using hmm
> do not have a bug).
Yes, I also would prefer to drop the confusing checks entirely -
Christoph can you resend this patch?
Thanks,
Jason
next prev parent reply other threads:[~2019-08-15 19:22 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-06 16:05 hmm cleanups, v2 Christoph Hellwig
2019-08-06 16:05 ` [PATCH 01/15] amdgpu: remove -EAGAIN handling for hmm_range_fault Christoph Hellwig
2019-08-06 16:05 ` [PATCH 02/15] amdgpu: don't initialize range->list in amdgpu_hmm_init_range Christoph Hellwig
2019-08-06 16:05 ` [PATCH 03/15] nouveau: pass struct nouveau_svmm to nouveau_range_fault Christoph Hellwig
2019-08-06 18:02 ` Jason Gunthorpe
2019-08-06 16:05 ` [PATCH 04/15] mm: remove the pgmap field from struct hmm_vma_walk Christoph Hellwig
2019-08-07 17:45 ` Jason Gunthorpe
2019-08-07 18:47 ` Dan Williams
2019-08-08 6:59 ` Christoph Hellwig
2019-08-14 1:36 ` Dan Williams
2019-08-14 7:38 ` Christoph Hellwig
2019-08-14 13:27 ` Jason Gunthorpe
2019-08-14 14:48 ` Dan Williams
2019-08-15 18:03 ` Jerome Glisse
2019-08-15 19:22 ` Jason Gunthorpe [this message]
2019-08-15 19:36 ` Dan Williams
2019-08-15 19:43 ` Jerome Glisse
2019-08-15 20:12 ` Dan Williams
2019-08-15 20:33 ` Jerome Glisse
2019-08-15 20:41 ` Jason Gunthorpe
2019-08-15 20:47 ` Dan Williams
2019-08-16 0:40 ` Jason Gunthorpe
2019-08-16 3:54 ` Dan Williams
2019-08-16 12:24 ` Jason Gunthorpe
2019-08-16 17:21 ` Dan Williams
2019-08-16 17:28 ` Jason Gunthorpe
2019-08-16 21:10 ` Ralph Campbell
2019-08-15 20:51 ` Jerome Glisse
2019-08-16 0:43 ` Jason Gunthorpe
2019-08-16 4:44 ` Christoph Hellwig
2019-08-16 12:30 ` Jason Gunthorpe
2019-08-16 12:34 ` Christoph Hellwig
2019-08-16 4:41 ` Christoph Hellwig
2019-08-06 16:05 ` [PATCH 05/15] mm: remove the unused vma argument to hmm_range_dma_unmap Christoph Hellwig
2019-08-06 16:05 ` [PATCH 06/15] mm: remove superflous arguments from hmm_range_register Christoph Hellwig
2019-08-06 16:05 ` [PATCH 07/15] mm: remove the page_shift member from struct hmm_range Christoph Hellwig
2019-08-07 17:51 ` Jason Gunthorpe
2019-08-06 16:05 ` [PATCH 08/15] mm: remove the mask variable in hmm_vma_walk_hugetlb_entry Christoph Hellwig
2019-08-06 18:02 ` Jason Gunthorpe
2019-08-06 16:05 ` [PATCH 09/15] mm: don't abuse pte_index() in hmm_vma_handle_pmd Christoph Hellwig
2019-08-07 17:18 ` Jason Gunthorpe
2019-08-06 16:05 ` [PATCH 10/15] mm: only define hmm_vma_walk_pud if needed Christoph Hellwig
2019-08-06 16:05 ` [PATCH 11/15] mm: cleanup the hmm_vma_handle_pmd stub Christoph Hellwig
2019-08-06 18:00 ` Jason Gunthorpe
2019-08-06 16:05 ` [PATCH 12/15] mm: cleanup the hmm_vma_walk_hugetlb_entry stub Christoph Hellwig
2019-08-06 16:05 ` [PATCH 13/15] mm: allow HMM_MIRROR on all architectures with MMU Christoph Hellwig
2019-08-06 16:05 ` [PATCH 14/15] mm: make HMM_MIRROR an implicit option Christoph Hellwig
2019-08-06 17:44 ` Jason Gunthorpe
2019-08-06 16:05 ` [PATCH 15/15] amdgpu: remove CONFIG_DRM_AMDGPU_USERPTR Christoph Hellwig
2019-08-06 17:44 ` Jason Gunthorpe
2019-08-06 17:51 ` Kuehling, Felix
2019-08-06 18:58 ` Alex Deucher
2019-08-06 20:03 ` Jason Gunthorpe
2019-08-07 6:57 ` Koenig, Christian
2019-08-07 11:46 ` Jason Gunthorpe
2019-08-07 18:17 ` hmm cleanups, v2 Jason Gunthorpe
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=20190815192157.GB22970@mellanox.com \
--to=jgg@mellanox.com \
--cc=Felix.Kuehling@amd.com \
--cc=amd-gfx@lists.freedesktop.org \
--cc=bskeggs@redhat.com \
--cc=dan.j.williams@intel.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=hch@lst.de \
--cc=jglisse@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--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).