[patch 076/262] mm: introduce pmd_install() helper

Andrew Morton
2021-11-05T20:38:41Z

From: Qi Zheng <zhengqi.arch@bytedance.com>
Subject: mm: introduce pmd_install() helper

Patch series "Do some code cleanups related to mm", v3.

This patch (of 2):

Currently we have three times the same few lines repeated in the code.
Deduplicate them by newly introduced pmd_install() helper.

Link: https://lkml.kernel.org/r/20210901102722.47686-1-zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/20210901102722.47686-2-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Mika Penttila <mika.penttila@nextfour.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/filemap.c | 11 ++---------
mm/internal.h | 1 +
mm/memory.c | 34 ++++++++++++++++------------------
3 files changed, 19 insertions(+), 27 deletions(-)

--- a/mm/filemap.c~mm-introduce-pmd_install-helper
+++ a/mm/filemap.c
@@ -3211,15 +3211,8 @@ static bool filemap_map_pmd(struct vm_fa
}
}

- if (pmd_none(*vmf->pmd)) {
- vmf->ptl = pmd_lock(mm, vmf->pmd);
- if (likely(pmd_none(*vmf->pmd))) {
- mm_inc_nr_ptes(mm);
- pmd_populate(mm, vmf->pmd, vmf->prealloc_pte);
- vmf->prealloc_pte = NULL;
- }
- spin_unlock(vmf->ptl);
- }
+ if (pmd_none(*vmf->pmd))
+ pmd_install(mm, vmf->pmd, &vmf->prealloc_pte);

/* See comment in handle_pte_fault() */
if (pmd_devmap_trans_unstable(vmf->pmd)) {
--- a/mm/internal.h~mm-introduce-pmd_install-helper
+++ a/mm/internal.h
@@ -38,6 +38,7 @@ vm_fault_t do_swap_page(struct vm_fault

void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *start_vma,
unsigned long floor, unsigned long ceiling);
+void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte);

static inline bool can_madv_lru_vma(struct vm_area_struct *vma)
{
--- a/mm/memory.c~mm-introduce-pmd_install-helper
+++ a/mm/memory.c
@@ -437,9 +437,20 @@ void free_pgtables(struct mmu_gather *tl
}
}

+void pmd_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte)
+{
+ spinlock_t *ptl = pmd_lock(mm, pmd);
+
+ if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
+ mm_inc_nr_ptes(mm);
+ pmd_populate(mm, pmd, *pte);
+ *pte = NULL;
+ }
+ spin_unlock(ptl);
+}
+
int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
{
- spinlock_t *ptl;
pgtable_t new = pte_alloc_one(mm);
if (!new)
return -ENOMEM;
@@ -459,13 +470,7 @@ int __pte_alloc(struct mm_struct *mm, pm
*/
smp_wmb(); /* Could be smp_wmb__xxx(before|after)_spin_lock */

- ptl = pmd_lock(mm, pmd);
- if (likely(pmd_none(*pmd))) { /* Has another populated it ? */
- mm_inc_nr_ptes(mm);
- pmd_populate(mm, pmd, new);
- new = NULL;
- }
- spin_unlock(ptl);
+ pmd_install(mm, pmd, &new);
if (new)
pte_free(mm, new);
return 0;
@@ -4028,17 +4033,10 @@ vm_fault_t finish_fault(struct vm_fault
return ret;
}

- if (vmf->prealloc_pte) {
- vmf->ptl = pmd_lock(vma->vm_mm, vmf->pmd);
- if (likely(pmd_none(*vmf->pmd))) {
- mm_inc_nr_ptes(vma->vm_mm);
- pmd_populate(vma->vm_mm, vmf->pmd, vmf->prealloc_pte);
- vmf->prealloc_pte = NULL;
- }
- spin_unlock(vmf->ptl);
- } else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd))) {
+ if (vmf->prealloc_pte)
+ pmd_install(vma->vm_mm, vmf->pmd, &vmf->prealloc_pte);
+ else if (unlikely(pte_alloc(vma->vm_mm, vmf->pmd)))
return VM_FAULT_OOM;
- }
}

/* See comment in handle_pte_fault() */
_