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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 <aneesh.kumar@linux.ibm.com>
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
hifive-unleashed-5.1
Christophe Leroy 2018-11-29 14:06:53 +00:00 committed by Michael Ellerman
parent a95d133c86
commit 2a146533bf
2 changed files with 6 additions and 0 deletions
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3
arch/powerpc/mm/pgtable-book3s64.c
View File

@ -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) {

3
arch/powerpc/mm/pgtable-frag.c
View File

@ -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) {