From: Gavin Shan <gshan@redhat.com>
To: Anshuman Khandual <anshuman.khandual@arm.com>,
Sudarshan Rajagopalan <sudaraja@codeaurora.org>,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Cc: Mark Rutland <mark.rutland@arm.com>,
David Hildenbrand <david@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Steven Price <steven.price@arm.com>,
Logan Gunthorpe <logang@deltatee.com>,
Andrew Morton <akpm@linux-foundation.org>,
Will Deacon <will@kernel.org>
Subject: Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory
Date: Mon, 12 Oct 2020 13:54:40 +1100 [thread overview]
Message-ID: <c61139c9-0949-e602-f880-9731eafc7a67@redhat.com> (raw)
In-Reply-To: <49dd60a7-25f4-8dc1-b905-088dff2a84fb@arm.com>
On 10/6/20 2:36 PM, Anshuman Khandual wrote:
> On 10/02/2020 01:46 AM, Sudarshan Rajagopalan wrote:
>> When section mappings are enabled, we allocate vmemmap pages from physically
>> continuous memory of size PMD_SIZE using vmemmap_alloc_block_buf(). Section
>> mappings are good to reduce TLB pressure. But when system is highly fragmented
>> and memory blocks are being hot-added at runtime, its possible that such
>> physically continuous memory allocations can fail. Rather than failing the
>> memory hot-add procedure, add a fallback option to allocate vmemmap pages from
>> discontinuous pages using vmemmap_populate_basepages().
>>
>> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org>
>> Cc: Catalin Marinas <catalin.marinas@arm.com>
>> Cc: Will Deacon <will@kernel.org>
>> Cc: Anshuman Khandual <anshuman.khandual@arm.com>
>> Cc: Mark Rutland <mark.rutland@arm.com>
>> Cc: Logan Gunthorpe <logang@deltatee.com>
>> Cc: David Hildenbrand <david@redhat.com>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Steven Price <steven.price@arm.com>
>> ---
>> arch/arm64/mm/mmu.c | 11 +++++++++--
>> 1 file changed, 9 insertions(+), 2 deletions(-)
>>
It looks good to me with Anshuman's comments fixed:
Reviewed-by: Gavin Shan <gshan@redhat.com>
>> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c
>> index 75df62f..11f8639 100644
>> --- a/arch/arm64/mm/mmu.c
>> +++ b/arch/arm64/mm/mmu.c
>> @@ -1121,8 +1121,15 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node,
>> void *p = NULL;
>>
>> p = vmemmap_alloc_block_buf(PMD_SIZE, node, altmap);
>> - if (!p)
>> - return -ENOMEM;
>> + if (!p) {
>> + /*
>> + * fallback allocating with virtually
>> + * contiguous memory for this section
>> + */
>
> Mapping is always virtually contiguous with or without huge pages.
> Please drop this comment here, as it's obvious.
>
>> + if (vmemmap_populate_basepages(addr, next, node, NULL))
>> + return -ENOMEM;
>
> Please send in the 'altmap' instead of NULL for allocation from
> device memory if and when requested.
>
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
>
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next prev parent reply other threads:[~2020-10-12 2:56 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-01 20:16 [PATCH v3] arm64/mm: add fallback option to allocate virtually Sudarshan Rajagopalan
2020-10-01 20:16 ` [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory Sudarshan Rajagopalan
2020-10-06 3:36 ` Anshuman Khandual
2020-10-12 2:54 ` Gavin Shan [this message]
2020-10-12 23:05 Sudarshan Rajagopalan
2020-10-12 23:05 ` Sudarshan Rajagopalan
2020-10-13 11:38 ` Anshuman Khandual
2020-10-15 0:54 ` Sudarshan Rajagopalan
2020-10-15 0:51 Sudarshan Rajagopalan
2020-10-15 0:51 ` Sudarshan Rajagopalan
2020-10-15 8:36 ` Will Deacon
2020-10-16 18:49 ` Sudarshan Rajagopalan
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