linux-kernel - [PATCH 4.19 12/34] mm: page_vma_mapped

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Message-Id: <20210709131651.384469016@linuxfoundation.org>
Date:   Fri,  9 Jul 2021 15:20:28 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Hugh Dickins <hughd@...gle.com>,
        "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
        Peter Xu <peterx@...hat.com>,
        Alistair Popple <apopple@...dia.com>,
        Matthew Wilcox <willy@...radead.org>,
        Ralph Campbell <rcampbell@...dia.com>,
        Wang Yugui <wangyugui@...-tech.com>,
        Will Deacon <will@...nel.org>, Yang Shi <shy828301@...il.com>,
        Zi Yan <ziy@...dia.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 12/34] mm: page_vma_mapped_walk(): settle PageHuge on entry

From: Hugh Dickins <hughd@...gle.com>

[ Upstream commit 6d0fd5987657cb0c9756ce684e3a74c0f6351728 ]

page_vma_mapped_walk() cleanup: get the hugetlbfs PageHuge case out of
the way at the start, so no need to worry about it later.

Link: https://lkml.kernel.org/r/e31a483c-6d73-a6bb-26c5-43c3b880a2@google.com
Signed-off-by: Hugh Dickins <hughd@...gle.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Reviewed-by: Peter Xu <peterx@...hat.com>
Cc: Alistair Popple <apopple@...dia.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Ralph Campbell <rcampbell@...dia.com>
Cc: Wang Yugui <wangyugui@...-tech.com>
Cc: Will Deacon <will@...nel.org>
Cc: Yang Shi <shy828301@...il.com>
Cc: Zi Yan <ziy@...dia.com>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 mm/page_vma_mapped.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index d146f6d31a62..036ce20bb154 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -148,10 +148,11 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 	if (pvmw->pmd && !pvmw->pte)
 		return not_found(pvmw);
 
-	if (pvmw->pte)
-		goto next_pte;
-
 	if (unlikely(PageHuge(page))) {
+		/* The only possible mapping was handled on last iteration */
+		if (pvmw->pte)
+			return not_found(pvmw);
+
 		/* when pud is not present, pte will be NULL */
 		pvmw->pte = huge_pte_offset(mm, pvmw->address,
 					    PAGE_SIZE << compound_order(page));
@@ -164,6 +165,9 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 			return not_found(pvmw);
 		return true;
 	}
+
+	if (pvmw->pte)
+		goto next_pte;
 restart:
 	pgd = pgd_offset(mm, pvmw->address);
 	if (!pgd_present(*pgd))
@@ -229,7 +233,7 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 			return true;
 next_pte:
 		/* Seek to next pte only makes sense for THP */
-		if (!PageTransHuge(page) || PageHuge(page))
+		if (!PageTransHuge(page))
 			return not_found(pvmw);
 		end = vma_address_end(page, pvmw->vma);
 		do {
-- 
2.30.2