The patch titled
Subject: mm: thp: skip make PMD PROT_NONE if THP migration is not supported
has been removed from the -mm tree. Its filename was
mm-thp-skip-make-pmd-prot_none-if-thp-migration-is-not-supported.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Yang Shi <shy828301@xxxxxxxxx>
Subject: mm: thp: skip make PMD PROT_NONE if THP migration is not supported
A quick grep shows x86_64, PowerPC (book3s), ARM64 and S390 support both
NUMA balancing and THP. But S390 doesn't support THP migration so NUMA
balancing actually can't migrate any misplaced pages.
Skip make PMD PROT_NONE for such case otherwise CPU cycles may be wasted
by pointless NUMA hinting faults on S390.
Link: https://lkml.kernel.org/r/20210518200801.7413-8-shy828301@xxxxxxxxx
Signed-off-by: Yang Shi <shy828301@xxxxxxxxx>
Acked-by: Mel Gorman <mgorman@xxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Cc: Zi Yan <ziy@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/huge_memory.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/mm/huge_memory.c~mm-thp-skip-make-pmd-prot_none-if-thp-migration-is-not-supported
+++ a/mm/huge_memory.c
@@ -1742,6 +1742,7 @@ bool move_huge_pmd(struct vm_area_struct
* Returns
* - 0 if PMD could not be locked
* - 1 if PMD was locked but protections unchanged and TLB flush unnecessary
+ * or if prot_numa but THP migration is not supported
* - HPAGE_PMD_NR if protections changed and TLB flush necessary
*/
int change_huge_pmd(struct vm_area_struct *vma, pmd_t *pmd,
@@ -1756,6 +1757,9 @@ int change_huge_pmd(struct vm_area_struc
bool uffd_wp = cp_flags & MM_CP_UFFD_WP;
bool uffd_wp_resolve = cp_flags & MM_CP_UFFD_WP_RESOLVE;
+ if (prot_numa && !thp_migration_supported())
+ return 1;
+
ptl = __pmd_trans_huge_lock(pmd, vma);
if (!ptl)
return 0;
_
Patches currently in -mm which might be from shy828301@xxxxxxxxx are
