From: Nicholas Piggin <npiggin@gmail.com>
To: "akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: "christophe.leroy@csgroup.eu" <christophe.leroy@csgroup.eu>,
"hch@infradead.org" <hch@infradead.org>,
"Jonathan.Cameron@Huawei.com" <Jonathan.Cameron@Huawei.com>,
"linux-arch@vger.kernel.org" <linux-arch@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linuxppc-dev@lists.ozlabs.org" <linuxppc-dev@lists.ozlabs.org>,
"lizefan@huawei.com" <lizefan@huawei.com>
Subject: Re: [PATCH v8 11/12] mm/vmalloc: Hugepage vmalloc mappings
Date: Sat, 05 Dec 2020 14:49:00 +1000 [thread overview]
Message-ID: <1607142139.ple4gyiix8.astroid@bobo.none> (raw)
In-Reply-To: <2e8e1f3e47736e8f5e749cee85b7036cbf9cb1b5.camel@intel.com>
Excerpts from Edgecombe, Rick P's message of December 5, 2020 4:33 am:
> On Fri, 2020-12-04 at 18:12 +1000, Nicholas Piggin wrote:
>> Excerpts from Edgecombe, Rick P's message of December 1, 2020 6:21
>> am:
>> > On Sun, 2020-11-29 at 01:25 +1000, Nicholas Piggin wrote:
>> > > Support huge page vmalloc mappings. Config option
>> > > HAVE_ARCH_HUGE_VMALLOC
>> > > enables support on architectures that define HAVE_ARCH_HUGE_VMAP
>> > > and
>> > > supports PMD sized vmap mappings.
>> > >
>> > > vmalloc will attempt to allocate PMD-sized pages if allocating
>> > > PMD
>> > > size
>> > > or larger, and fall back to small pages if that was unsuccessful.
>> > >
>> > > Allocations that do not use PAGE_KERNEL prot are not permitted to
>> > > use
>> > > huge pages, because not all callers expect this (e.g., module
>> > > allocations vs strict module rwx).
>> >
>> > Several architectures (x86, arm64, others?) allocate modules
>> > initially
>> > with PAGE_KERNEL and so I think this test will not exclude module
>> > allocations in those cases.
>>
>> Ah, thanks. I guess archs must additionally ensure that their
>> PAGE_KERNEL allocations are suitable for huge page mappings before
>> enabling the option.
>>
>> If there is interest from those archs to support this, I have an
>> early (un-posted) patch that adds an explicit VM_HUGE flag that could
>> override the pessemistic arch default. It's not much trouble to add
>> this
>> to the large system hash allocations. It's very out of date now but
>> I
>> can at least give what I have to anyone doing an arch support that
>> wants it.
>
> Ahh, sorry, I totally missed that this was only enabled for powerpc.
>
> That patch might be useful for me actually. Or maybe a VM_NOHUGE, since
> there are only a few places where executable vmallocs are created? I'm
> not sure what the other issues are.
Yeah good question, VM_HUGE might be safer but maybe it would be
possible there's only a few problems that have to be annotated with
VM_NOHUGE, good point. I'll dig it out and see.
> I am endeavoring to have small module allocations share large pages, so
> this infrastructure is a big help already.
> https://lore.kernel.org/lkml/20201120202426.18009-1-rick.p.edgecombe@intel.com/
Oh nice that's what I wanted to do next! We should try get this work
for x86 as well then.
Thanks,
Nick
next prev parent reply other threads:[~2020-12-05 4:50 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-28 15:25 [PATCH v8 00/12] huge vmalloc mappings Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 01/12] mm/vmalloc: fix vmalloc_to_page for huge vmap mappings Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 02/12] mm: apply_to_pte_range warn and fail if a large pte is encountered Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 03/12] mm/vmalloc: rename vmap_*_range vmap_pages_*_range Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 04/12] mm/ioremap: rename ioremap_*_range to vmap_*_range Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 05/12] mm: HUGE_VMAP arch support cleanup Nicholas Piggin
2020-12-01 14:21 ` Catalin Marinas
2020-11-28 15:25 ` [PATCH v8 06/12] powerpc: inline huge vmap supported functions Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 07/12] arm64: " Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 08/12] x86: " Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 09/12] mm: Move vmap_range from mm/ioremap.c to mm/vmalloc.c Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 10/12] mm/vmalloc: add vmap_range_noflush variant Nicholas Piggin
2020-11-28 15:25 ` [PATCH v8 11/12] mm/vmalloc: Hugepage vmalloc mappings Nicholas Piggin
2020-11-28 17:07 ` kernel test robot
2020-11-28 17:41 ` kernel test robot
2020-11-30 20:21 ` Edgecombe, Rick P
2020-11-30 21:42 ` Edgecombe, Rick P
2020-12-04 8:12 ` Nicholas Piggin
2020-12-04 18:33 ` Edgecombe, Rick P
2020-12-05 4:49 ` Nicholas Piggin [this message]
2020-11-28 15:25 ` [PATCH v8 12/12] powerpc/64s/radix: Enable huge " Nicholas Piggin
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