Switch from per mm_struct to per pmd page table lock by enabling
ARCH_ENABLE_SPLIT_PMD_PTLOCK. This provides better granularity for
large system.
I'm not sure if there is contention on mm->page_table_lock. Given
the option comes at no cost (apart from initializing more spin
locks), why not enable it now.
Signed-off-by: Yu Zhao <yuzhao@xxxxxxxxxx>
---
arch/arm64/Kconfig | 3 +++
arch/arm64/include/asm/pgalloc.h | 12 +++++++++++-
arch/arm64/include/asm/tlb.h | 5 ++++-
3 files changed, 18 insertions(+), 2 deletions(-)
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index a4168d366127..8dbfa49d926c 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -872,6 +872,9 @@ config ARCH_WANT_HUGE_PMD_SHARE
config ARCH_HAS_CACHE_LINE_SIZE
def_bool y
+config ARCH_ENABLE_SPLIT_PMD_PTLOCK
+ def_bool y if PGTABLE_LEVELS > 2
+
config SECCOMP
bool "Enable seccomp to safely compute untrusted bytecode"
---help---
diff --git a/arch/arm64/include/asm/pgalloc.h b/arch/arm64/include/asm/pgalloc.h
index 52fa47c73bf0..dabba4b2c61f 100644
--- a/arch/arm64/include/asm/pgalloc.h
+++ b/arch/arm64/include/asm/pgalloc.h
@@ -33,12 +33,22 @@
static inline pmd_t *pmd_alloc_one(struct mm_struct *mm, unsigned long addr)
{
- return (pmd_t *)__get_free_page(PGALLOC_GFP);
+ struct page *page;
+
+ page = alloc_page(PGALLOC_GFP);
+ if (!page)
+ return NULL;
+ if (!pgtable_pmd_page_ctor(page)) {
+ __free_page(page);
+ return NULL;
+ }
+ return page_address(page);
}
static inline void pmd_free(struct mm_struct *mm, pmd_t *pmdp)
{
BUG_ON((unsigned long)pmdp & (PAGE_SIZE-1));
+ pgtable_pmd_page_dtor(virt_to_page(pmdp));
free_page((unsigned long)pmdp);
}
diff --git a/arch/arm64/include/asm/tlb.h b/arch/arm64/include/asm/tlb.h
index 106fdc951b6e..4e3becfed387 100644
--- a/arch/arm64/include/asm/tlb.h
+++ b/arch/arm64/include/asm/tlb.h
@@ -62,7 +62,10 @@ static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t pte,
static inline void __pmd_free_tlb(struct mmu_gather *tlb, pmd_t *pmdp,
unsigned long addr)
{
- tlb_remove_table(tlb, virt_to_page(pmdp));
+ struct page *page = virt_to_page(pmdp);
+
+ pgtable_pmd_page_dtor(page);
+ tlb_remove_table(tlb, page);
}
#endif
--
2.21.0.rc0.258.g878e2cd30e-goog
