Messages in this thread | | | Date | Wed, 14 Oct 2020 17:54:16 -0700 | From | Sudarshan Rajagopalan <> | Subject | Re: [PATCH v3] arm64/mm: add fallback option to allocate virtually contiguous memory |
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On 2020-10-13 04:38, Anshuman Khandual wrote: > On 10/13/2020 04:35 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(). > > There is a checkpatch warning here, which could be fixed while merging > ? > > WARNING: Possible unwrapped commit description (prefer a maximum 75 > chars per line) > #7: > When section mappings are enabled, we allocate vmemmap pages from > physically > > total: 0 errors, 1 warnings, 13 lines checked >
Thanks Anshuman for the review. I sent out an updated patch fixing the checkpatch warning.
>> >> Signed-off-by: Sudarshan Rajagopalan <sudaraja@codeaurora.org> >> Reviewed-by: Gavin Shan <gshan@redhat.com> >> 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> > > Nonetheless, this looks fine. Did not see any particular problem > while creating an experimental vmemmap with interleaving section > and base page mapping. > > Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> > >> --- >> arch/arm64/mm/mmu.c | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index 75df62fea1b6..44486fd0e883 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -1121,8 +1121,11 @@ 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) { >> + if (vmemmap_populate_basepages(addr, next, node, altmap)) >> + return -ENOMEM; >> + continue; >> + } >> >> pmd_set_huge(pmdp, __pa(p), __pgprot(PROT_SECT_NORMAL)); >> } else >>
Sudarshan
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