From: Matthew Wilcox <willy@infradead.org>
To: Christophe Leroy <christophe.leroy@c-s.fr>
Cc: Nicholas Piggin <npiggin@gmail.com>,
linux-arch@vger.kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Will Deacon <will@kernel.org>,
x86@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
Catalin Marinas <catalin.marinas@arm.com>,
Thomas Gleixner <tglx@linutronix.de>,
linuxppc-dev@lists.ozlabs.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [PATCH v2 4/4] mm/vmalloc: Hugepage vmalloc mappings
Date: Tue, 14 Apr 2020 07:20:14 -0700 [thread overview]
Message-ID: <20200414142014.GO21484@bombadil.infradead.org> (raw)
In-Reply-To: <36616218-1d3a-b18a-8fb8-4fc9eff22780@c-s.fr>
On Tue, Apr 14, 2020 at 02:28:35PM +0200, Christophe Leroy wrote:
> Le 13/04/2020 à 15:41, Matthew Wilcox a écrit :
> > On Mon, Apr 13, 2020 at 10:53:03PM +1000, Nicholas Piggin wrote:
> > > +static int vmap_pages_range_noflush(unsigned long start, unsigned long end,
> > > + pgprot_t prot, struct page **pages,
> > > + unsigned int page_shift)
> > > +{
> > > + if (page_shift == PAGE_SIZE) {
> >
> > ... I think you meant 'page_shift == PAGE_SHIFT'
> >
> > Overall I like this series, although it's a bit biased towards CPUs
> > which have page sizes which match PMD/PUD sizes. It doesn't offer the
> > possibility of using 64kB page sizes on ARM, for example. But it's a
> > step in the right direction.
>
> I was going to ask more or less the same question, I would have liked to use
> 512kB hugepages on powerpc 8xx.
>
> Even the 8M hugepages (still on the 8xx), can they be used as well, taking
> into account that two PGD entries have to point to the same 8M page ?
>
> I sent out a series which tends to make the management of 512k and 8M pages
> closer to what Linux expects, in order to use them inside kernel, for Linear
> mappings and Kasan mappings for the moment. See
> https://patchwork.ozlabs.org/project/linuxppc-dev/list/?series=164620
> It would be nice if we could amplify it a use it for ioremaps and vmallocs
> as well.
I haven't been looking at vmalloc at all; I've been looking at the page
cache. See:
https://lore.kernel.org/linux-mm/20200212041845.25879-1-willy@infradead.org/
Once we have large pages in the page cache, I want to sort out the API
for asking the CPU to insert a TLB entry. Right now, we use set_pte_at(),
set_pmd_at() and set_pud_at(). I'm thinking something along the lines of:
vm_fault_t vmf_set_page_at(struct vm_fault *vmf, struct page *page);
and the architecture can insert whatever PTEs and/or TLB entries it
likes based on compound_order(page) -- if, say, it's a 1MB page, it might
choose to insert 2 * 512kB entries, or just the upper or lower 512kB entry
(depending which half of the 1MB page the address sits in).
next prev parent reply other threads:[~2020-04-14 14:20 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-13 12:52 [PATCH v2 0/4] huge vmalloc mappings Nicholas Piggin
2020-04-13 12:53 ` [PATCH v2 1/4] mm/vmalloc: fix vmalloc_to_page for huge vmap mappings Nicholas Piggin
2020-04-13 13:34 ` Matthew Wilcox
2020-04-14 11:31 ` Nicholas Piggin
2020-04-13 12:53 ` [PATCH v2 2/4] mm: Move ioremap page table mapping function to mm/ Nicholas Piggin
2020-04-13 12:53 ` [PATCH v2 3/4] mm: HUGE_VMAP arch query functions cleanup Nicholas Piggin
2020-04-13 20:17 ` kbuild test robot
2020-04-13 20:29 ` kbuild test robot
2020-04-13 23:56 ` kbuild test robot
2020-04-13 23:56 ` [PATCH] mm: fix boolreturn.cocci warnings kbuild test robot
2020-04-13 12:53 ` [PATCH v2 4/4] mm/vmalloc: Hugepage vmalloc mappings Nicholas Piggin
2020-04-13 13:41 ` Matthew Wilcox
2020-04-14 11:39 ` Nicholas Piggin
2020-04-14 12:28 ` Christophe Leroy
2020-04-14 14:20 ` Matthew Wilcox [this message]
2020-04-14 7:23 ` Christoph Hellwig
2020-04-14 12:13 ` Nicholas Piggin
2020-04-14 13:02 ` Christoph Hellwig
2020-04-14 14:48 ` Nicholas Piggin
2020-04-15 10:47 ` Will Deacon
2020-04-16 2:38 ` Nicholas Piggin
2020-07-01 7:10 ` Zefan Li
2020-07-03 0:15 ` Nicholas Piggin
2020-07-20 2:02 ` Zefan Li
2020-07-20 2:49 ` Nicholas Piggin
2020-04-14 0:27 ` [PATCH v2 0/4] huge " David Rientjes
2020-04-14 12:23 ` Nicholas Piggin
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