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authorChristophe Leroy <christophe.leroy@c-s.fr>2018-11-29 14:06:53 +0000
committerMichael Ellerman <mpe@ellerman.id.au>2018-12-04 19:45:01 +1100
commit2a146533bf96af3fba97b1c91efe0416b1b24b95 (patch)
tree6b088db9efed497fbd2f43fe1b95d25988037ac3
parenta95d133c8643cae40a35f82184640d312ba9f11f (diff)
downloadlinux-2a146533bf96af3fba97b1c91efe0416b1b24b95.tar.bz2
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>
-rw-r--r--arch/powerpc/mm/pgtable-book3s64.c3
-rw-r--r--arch/powerpc/mm/pgtable-frag.c3
2 files changed, 6 insertions, 0 deletions
diff --git a/arch/powerpc/mm/pgtable-book3s64.c b/arch/powerpc/mm/pgtable-book3s64.c
index 0c0fd173208a..f3c31f5e1026 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 d61e7c2a9a79..7544d0d7177d 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) {