diff mbox series

[2/7] mm: introduce pte_install() helper

Message ID 20210718043034.76431-3-zhengqi.arch@bytedance.com (mailing list archive)
State New
Headers show
Series Free user PTE page table pages | expand

Commit Message

Qi Zheng July 18, 2021, 4:30 a.m. UTC 
Currently we have three times the same few lines repeated in the
code. Deduplicate them by newly introduced pte_install() helper.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 include/linux/mm.h |  1 +
 mm/filemap.c       | 11 ++---------
 mm/memory.c        | 34 ++++++++++++++++------------------
 3 files changed, 19 insertions(+), 27 deletions(-)

Comments

Kirill A . Shutemov July 18, 2021, 9:31 p.m. UTC | #1 
On Sun, Jul 18, 2021 at 12:30:28PM +0800, Qi Zheng wrote:
> Currently we have three times the same few lines repeated in the
> code. Deduplicate them by newly introduced pte_install() helper.
> 
> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>

I don't like the name of the helper: we have confusion of PTE being
PTE-entry or PTE page table. And pte_install() doing pmd_populate()
doesn't help the situation.

Maybe pmd_install()? Or pte_table_install()? I donno.
Qi Zheng July 19, 2021, 10:20 a.m. UTC | #2 
On 7/19/21 5:31 AM, Kirill A. Shutemov wrote:
> On Sun, Jul 18, 2021 at 12:30:28PM +0800, Qi Zheng wrote:
>> Currently we have three times the same few lines repeated in the
>> code. Deduplicate them by newly introduced pte_install() helper.
>>
>> Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
> 
> I don't like the name of the helper: we have confusion of PTE being
> PTE-entry or PTE page table. And pte_install() doing pmd_populate()
> doesn't help the situation.
> 
> Maybe pmd_install()? Or pte_table_install()? I donno.
> 

Look good to me, I will use pmd_install().
diff mbox series

Patch

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 57453dba41b9..5efd63a20d72 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2374,6 +2374,7 @@  static inline spinlock_t *pud_lock(struct mm_struct *mm, pud_t *pud)
 	return ptl;
 }
 
+extern void pte_install(struct mm_struct *mm, pmd_t *pmd, pgtable_t *pte);
 extern void __init pagecache_init(void);
 extern void __init free_area_init_memoryless_node(int nid);
 extern void free_initmem(void);
diff --git a/mm/filemap.c b/mm/filemap.c
index 7b365fdef7a5..4955641f2cf0 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3173,15 +3173,8 @@  static bool filemap_map_pmd(struct vm_fault *vmf, struct page *page)
 	    }
 	}
 
-	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))
+		pte_install(mm, vmf->pmd, &vmf->prealloc_pte);
 
 	/* See comment in handle_pte_fault() */
 	if (pmd_devmap_trans_unstable(vmf->pmd)) {
diff --git a/mm/memory.c b/mm/memory.c
index 94a17a9a48ab..a0ac4b33e07a 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -433,9 +433,20 @@  void free_pgtables(struct mmu_gather *tlb, struct vm_area_struct *vma,
 	}
 }
 
+void pte_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;
@@ -455,13 +466,7 @@  int __pte_alloc(struct mm_struct *mm, pmd_t *pmd)
 	 */
 	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);
+	pte_install(mm, pmd, &new);
 	if (new)
 		pte_free(mm, new);
 	return 0;
@@ -4026,17 +4031,10 @@  vm_fault_t finish_fault(struct vm_fault *vmf)
 				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)
+			pte_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() */