From 2a146533bf96af3fba97b1c91efe0416b1b24b95 Mon Sep 17 00:00:00 2001 From: Christophe Leroy Date: Thu, 29 Nov 2018 14:06:53 +0000 Subject: [PATCH] powerpc/mm: Avoid useless lock with single page fragments There is no point in taking the page table lock as pte_frag or pmd_frag are always NULL when we have only one fragment. Reviewed-by: Aneesh Kumar K.V Signed-off-by: Christophe Leroy Signed-off-by: Michael Ellerman --- arch/powerpc/mm/pgtable-book3s64.c | 3 +++ arch/powerpc/mm/pgtable-frag.c | 3 +++ 2 files changed, 6 insertions(+) diff --git a/arch/powerpc/mm/pgtable-book3s64.c b/arch/powerpc/mm/pgtable-book3s64.c index 0c0fd17..f3c31f5 100644 --- a/arch/powerpc/mm/pgtable-book3s64.c +++ b/arch/powerpc/mm/pgtable-book3s64.c @@ -244,6 +244,9 @@ static pmd_t *get_pmd_from_cache(struct mm_struct *mm) { void *pmd_frag, *ret; + if (PMD_FRAG_NR == 1) + return NULL; + spin_lock(&mm->page_table_lock); ret = mm->context.pmd_frag; if (ret) { diff --git a/arch/powerpc/mm/pgtable-frag.c b/arch/powerpc/mm/pgtable-frag.c index d61e7c2..7544d0d 100644 --- a/arch/powerpc/mm/pgtable-frag.c +++ b/arch/powerpc/mm/pgtable-frag.c @@ -34,6 +34,9 @@ static pte_t *get_pte_from_cache(struct mm_struct *mm) { void *pte_frag, *ret; + if (PTE_FRAG_NR == 1) + return NULL; + spin_lock(&mm->page_table_lock); ret = mm->context.pte_frag; if (ret) { -- 2.7.4