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 <sudar...@codeaurora.org>
Reviewed-by: Gavin Shan <gs...@redhat.com>
Cc: Catalin Marinas <catalin.mari...@arm.com>
Cc: Will Deacon <w...@kernel.org>
Cc: Anshuman Khandual <anshuman.khand...@arm.com>
Cc: Mark Rutland <mark.rutl...@arm.com>
Cc: Logan Gunthorpe <log...@deltatee.com>
Cc: David Hildenbrand <da...@redhat.com>
Cc: Andrew Morton <a...@linux-foundation.org>
Cc: Steven Price <steven.pr...@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.khand...@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
--
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a
Linux Foundation Collaborative Project
