linux-kernel - [PATCH] mm/hugetlb: Unify clearing of RestoreReserve for private pages

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Date:   Thu, 20 Oct 2022 15:38:32 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Muchun Song <songmuchun@...edance.com>, peterx@...hat.com,
        Mike Kravetz <mike.kravetz@...cle.com>
Subject: [PATCH] mm/hugetlb: Unify clearing of RestoreReserve for private pages

A trivial cleanup to move clearing of RestoreReserve into adding anon rmap
of private hugetlb mappings.  It matches with the shared mappings where we
only clear the bit when adding into page cache, rather than spreading it
around the code paths.

Cc: Mike Kravetz <mike.kravetz@...cle.com>
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 mm/hugetlb.c | 14 ++++----------
 mm/rmap.c    |  2 +-
 2 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 1a7dc7b2e16c..931789a8f734 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -4784,7 +4784,6 @@ hugetlb_install_page(struct vm_area_struct *vma, pte_t *ptep, unsigned long addr
 	hugepage_add_new_anon_rmap(new_page, vma, addr);
 	set_huge_pte_at(vma->vm_mm, addr, ptep, make_huge_pte(vma, new_page, 1));
 	hugetlb_count_add(pages_per_huge_page(hstate_vma(vma)), vma->vm_mm);
-	ClearHPageRestoreReserve(new_page);
 	SetHPageMigratable(new_page);
 }
 
@@ -5447,8 +5446,6 @@ static vm_fault_t hugetlb_wp(struct mm_struct *mm, struct vm_area_struct *vma,
 	spin_lock(ptl);
 	ptep = huge_pte_offset(mm, haddr, huge_page_size(h));
 	if (likely(ptep && pte_same(huge_ptep_get(ptep), pte))) {
-		ClearHPageRestoreReserve(new_page);
-
 		/* Break COW or unshare */
 		huge_ptep_clear_flush(vma, haddr, ptep);
 		mmu_notifier_invalidate_range(mm, range.start, range.end);
@@ -5743,10 +5740,9 @@ static vm_fault_t hugetlb_no_page(struct mm_struct *mm,
 	if (!pte_same(huge_ptep_get(ptep), old_pte))
 		goto backout;
 
-	if (anon_rmap) {
-		ClearHPageRestoreReserve(page);
+	if (anon_rmap)
 		hugepage_add_new_anon_rmap(page, vma, haddr);
-	} else
+	else
 		page_dup_file_rmap(page, true);
 	new_pte = make_huge_pte(vma, page, ((vma->vm_flags & VM_WRITE)
 				&& (vma->vm_flags & VM_SHARED)));
@@ -6133,12 +6129,10 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm,
 	if (!huge_pte_none_mostly(huge_ptep_get(dst_pte)))
 		goto out_release_unlock;
 
-	if (page_in_pagecache) {
+	if (page_in_pagecache)
 		page_dup_file_rmap(page, true);
-	} else {
-		ClearHPageRestoreReserve(page);
+	else
 		hugepage_add_new_anon_rmap(page, dst_vma, dst_addr);
-	}
 
 	/*
 	 * For either: (1) CONTINUE on a non-shared VMA, or (2) UFFDIO_COPY
diff --git a/mm/rmap.c b/mm/rmap.c
index 9bba65b30e4d..3b2d18bbdc44 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -2571,7 +2571,7 @@ void hugepage_add_new_anon_rmap(struct page *page,
 	BUG_ON(address < vma->vm_start || address >= vma->vm_end);
 	atomic_set(compound_mapcount_ptr(page), 0);
 	atomic_set(compound_pincount_ptr(page), 0);
-
+	ClearHPageRestoreReserve(page);
 	__page_set_anon_rmap(page, vma, address, 1);
 }
 #endif /* CONFIG_HUGETLB_PAGE */
-- 
2.37.3