All of lore.kernel.org
 help / color / mirror / Atom feed
From: Christoph Hellwig <hch@lst.de>
To: Ralph Campbell <rcampbell@nvidia.com>
Cc: nouveau@lists.freedesktop.org, linux-rdma@vger.kernel.org,
	linux-mm@kvack.org, linux-kselftest@vger.kernel.org,
	linux-kernel@vger.kernel.org, Jerome Glisse <jglisse@redhat.com>,
	John Hubbard <jhubbard@nvidia.com>,
	Christoph Hellwig <hch@lst.de>,
	Jason Gunthorpe <jgg@mellanox.com>,
	Ben Skeggs <bskeggs@redhat.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Shuah Khan <shuah@linuxfoundation.org>,
	willy@infradead.org
Subject: Re: [PATCH 4/6] mm/hmm: add output flag for compound page mapping
Date: Fri, 8 May 2020 21:51:30 +0200	[thread overview]
Message-ID: <20200508195129.GA19740@lst.de> (raw)
In-Reply-To: <20200508192009.15302-5-rcampbell@nvidia.com>

On Fri, May 08, 2020 at 12:20:07PM -0700, Ralph Campbell wrote:
> hmm_range_fault() returns an array of page frame numbers and flags for
> how the pages are mapped in the requested process' page tables. The PFN
> can be used to get the struct page with hmm_pfn_to_page() and the page size
> order can be determined with compound_order(page) but if the page is larger
> than order 0 (PAGE_SIZE), there is no indication that the page is mapped
> using a larger page size. To be fully general, hmm_range_fault() would need
> to return the mapping size to handle cases like a 1GB compound page being
> mapped with 2MB PMD entries. However, the most common case is the mapping
> size the same as the underlying compound page size.
> Add a new output flag to indicate this so that callers know it is safe to
> use a large device page table mapping if one is available.

Why do you need the flag?  The caller should be able to just use
page_size() (or willys new thp_size helper).


WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>
To: Ralph Campbell <rcampbell-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
Cc: nouveau-PD4FTy7X32lNgt0PjOBp9y5qC8QIuHrW@public.gmane.org,
	linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org,
	linux-kselftest-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Jerome Glisse <jglisse-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	John Hubbard <jhubbard-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>,
	Christoph Hellwig <hch-jcswGhMUV9g@public.gmane.org>,
	Jason Gunthorpe <jgg-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Ben Skeggs <bskeggs-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Shuah Khan
	<shuah-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org>,
	willy-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org
Subject: Re: [PATCH 4/6] mm/hmm: add output flag for compound page mapping
Date: Fri, 8 May 2020 21:51:30 +0200	[thread overview]
Message-ID: <20200508195129.GA19740@lst.de> (raw)
In-Reply-To: <20200508192009.15302-5-rcampbell-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>

On Fri, May 08, 2020 at 12:20:07PM -0700, Ralph Campbell wrote:
> hmm_range_fault() returns an array of page frame numbers and flags for
> how the pages are mapped in the requested process' page tables. The PFN
> can be used to get the struct page with hmm_pfn_to_page() and the page size
> order can be determined with compound_order(page) but if the page is larger
> than order 0 (PAGE_SIZE), there is no indication that the page is mapped
> using a larger page size. To be fully general, hmm_range_fault() would need
> to return the mapping size to handle cases like a 1GB compound page being
> mapped with 2MB PMD entries. However, the most common case is the mapping
> size the same as the underlying compound page size.
> Add a new output flag to indicate this so that callers know it is safe to
> use a large device page table mapping if one is available.

Why do you need the flag?  The caller should be able to just use
page_size() (or willys new thp_size helper).

  reply	other threads:[~2020-05-08 19:51 UTC|newest]

Thread overview: 35+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-08 19:20 [PATCH 0/6] nouveau/hmm: add support for mapping large pages Ralph Campbell
2020-05-08 19:20 ` Ralph Campbell
2020-05-08 19:20 ` [PATCH 1/6] nouveau/hmm: map pages after migration Ralph Campbell
2020-05-08 19:20   ` Ralph Campbell
2020-05-08 19:20 ` [PATCH 2/6] nouveau: make nvkm_vmm_ctor() and nvkm_mmu_ptp_get() static Ralph Campbell
2020-05-08 19:20   ` Ralph Campbell
2020-05-08 19:20 ` [PATCH 3/6] nouveau/hmm: fault one page at a time Ralph Campbell
2020-05-08 19:20   ` Ralph Campbell
2020-05-08 19:20 ` [PATCH 4/6] mm/hmm: add output flag for compound page mapping Ralph Campbell
2020-05-08 19:20   ` Ralph Campbell
2020-05-08 19:51   ` Christoph Hellwig [this message]
2020-05-08 19:51     ` Christoph Hellwig
2020-05-08 20:06     ` Ralph Campbell
2020-05-08 20:06       ` Ralph Campbell
2020-05-26 22:29       ` Zi Yan
2020-05-26 22:29         ` Zi Yan
2020-05-26 22:47         ` Ralph Campbell
2020-05-26 22:47           ` Ralph Campbell
2020-05-08 19:20 ` [PATCH 5/6] nouveau/hmm: support mapping large sysmem pages Ralph Campbell
2020-05-08 19:20   ` Ralph Campbell
2020-05-08 19:20 ` [PATCH 6/6] hmm: add tests for HMM_PFN_COMPOUND flag Ralph Campbell
2020-05-08 19:20   ` Ralph Campbell
2020-05-08 19:59 ` [PATCH 0/6] nouveau/hmm: add support for mapping large pages Matthew Wilcox
2020-05-08 20:17   ` Ralph Campbell
2020-05-08 20:17     ` Ralph Campbell
2020-05-09  3:17     ` Matthew Wilcox
2020-05-09  3:17       ` Matthew Wilcox
2020-05-11 17:07       ` Ralph Campbell
2020-05-11 17:07         ` Ralph Campbell
2020-05-25 13:41 ` Jason Gunthorpe
2020-05-25 13:41   ` Jason Gunthorpe
2020-05-26 17:32   ` Ralph Campbell
2020-05-26 17:32     ` Ralph Campbell
2020-05-29 23:24     ` Jason Gunthorpe
2020-05-29 23:24       ` 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=20200508195129.GA19740@lst.de \
    --to=hch@lst.de \
    --cc=akpm@linux-foundation.org \
    --cc=bskeggs@redhat.com \
    --cc=jgg@mellanox.com \
    --cc=jglisse@redhat.com \
    --cc=jhubbard@nvidia.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=linux-rdma@vger.kernel.org \
    --cc=nouveau@lists.freedesktop.org \
    --cc=rcampbell@nvidia.com \
    --cc=shuah@linuxfoundation.org \
    --cc=willy@infradead.org \
    /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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.