* [PATCH v3] arm64/mm: add fallback option to allocate virtually @ 2020-10-01 20:16 Sudarshan Rajagopalan 2020-10-01 20:16 ` [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory Sudarshan Rajagopalan 0 siblings, 1 reply; 4+ messages in thread From: Sudarshan Rajagopalan @ 2020-10-01 20:16 UTC (permalink / raw) To: linux-arm-kernel, linux-kernel; +Cc: Sudarshan Rajagopalan V1: The initial patch used the approach to abort at the first instance of PMD_SIZE allocation failure, unmaps all previously mapped sections using vmemmap_free and maps the entire request with vmemmap_populate_basepages to allocate virtually contiguous memory. https://lkml.org/lkml/2020/9/10/66 V2: Allocates virtually contiguous memory only for sections that failed PMD_SIZE allocation, and continues to allocate physically contiguous memory for other sections. https://lkml.org/lkml/2020/9/30/1489 V3: Addresses Anshuman's comment to allow fallback to altmap base pages as well if and when required. Sudarshan Rajagopalan (1): arm64/mm: add fallback option to allocate virtually contiguous memory arch/arm64/mm/mmu.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 4+ messages in thread
* [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory 2020-10-01 20:16 [PATCH v3] arm64/mm: add fallback option to allocate virtually Sudarshan Rajagopalan @ 2020-10-01 20:16 ` Sudarshan Rajagopalan 2020-10-06 3:36 ` Anshuman Khandual 0 siblings, 1 reply; 4+ messages in thread From: Sudarshan Rajagopalan @ 2020-10-01 20:16 UTC (permalink / raw) To: linux-arm-kernel, linux-kernel Cc: Mark Rutland, Will Deacon, Anshuman Khandual, Catalin Marinas, Sudarshan Rajagopalan, David Hildenbrand, Steven Price, Andrew Morton, Logan Gunthorpe 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(-) 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 + */ + if (vmemmap_populate_basepages(addr, next, node, NULL)) + return -ENOMEM; + continue; + } pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL)); } else -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory 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 0 siblings, 1 reply; 4+ messages in thread From: Anshuman Khandual @ 2020-10-06 3:36 UTC (permalink / raw) To: Sudarshan Rajagopalan, linux-arm-kernel, linux-kernel Cc: Mark Rutland, Will Deacon, David Hildenbrand, Catalin Marinas, Steven Price, Andrew Morton, Logan Gunthorpe 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(-) > > 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 ^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory 2020-10-06 3:36 ` Anshuman Khandual @ 2020-10-12 2:54 ` Gavin Shan 0 siblings, 0 replies; 4+ messages in thread From: Gavin Shan @ 2020-10-12 2:54 UTC (permalink / raw) To: Anshuman Khandual, Sudarshan Rajagopalan, linux-arm-kernel, linux-kernel Cc: Mark Rutland, David Hildenbrand, Catalin Marinas, Steven Price, Logan Gunthorpe, Andrew Morton, Will Deacon 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 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel ^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2020-10-12 2:56 UTC | newest] Thread overview: 4+ messages (download: mbox.gz follow: Atom feed -- links below jump to the message on this page -- 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
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