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).
next prev parent reply other threads:[~2020-05-08 19:51 UTC|newest]
Thread overview: 18+ 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 ` [PATCH 1/6] nouveau/hmm: map pages after migration 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 ` [PATCH 3/6] nouveau/hmm: fault one page at a time Ralph Campbell
2020-05-08 19:20 ` [PATCH 4/6] mm/hmm: add output flag for compound page mapping Ralph Campbell
2020-05-08 19:51 ` Christoph Hellwig [this message]
2020-05-08 20:06 ` Ralph Campbell
2020-05-26 22:29 ` Zi Yan
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 ` [PATCH 6/6] hmm: add tests for HMM_PFN_COMPOUND flag 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
2020-05-09 3:17 ` Matthew Wilcox
2020-05-11 17:07 ` Ralph Campbell
2020-05-25 13:41 ` Jason Gunthorpe
2020-05-26 17:32 ` Ralph Campbell
2020-05-29 23:24 ` Jason Gunthorpe
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