From 9f84f39f5515fd412398a1019e3f50ac3ab51a80 Mon Sep 17 00:00:00 2001 From: Sudarshan Rajagopalan Date: Wed, 14 Oct 2020 17:51:23 -0700 Subject: [PATCH] arm64/mm: add fallback option to allocate virtually contiguous memory 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 Reviewed-by: Gavin Shan Reviewed-by: Anshuman Khandual Acked-by: Will Deacon Cc: Will Deacon Cc: Anshuman Khandual Cc: Mark Rutland Cc: Logan Gunthorpe Cc: David Hildenbrand Cc: Andrew Morton Cc: Steven Price Link: https://lore.kernel.org/r/d6c06f2ef39bbe6c715b2f6db76eb16155fdcee6.1602722808.git.sudaraja@codeaurora.org Signed-off-by: Catalin Marinas --- 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 1c0f3e0..a773d2a 100644 --- a/arch/arm64/mm/mmu.c +++ b/arch/arm64/mm/mmu.c @@ -1132,8 +1132,11 @@ 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 -- 2.7.4