linux-kernel - [PATCH 4.19 14/34] mm: page_vma_mapped_walk(): prettify PVMW

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Date:   Fri,  9 Jul 2021 15:20:30 +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 14/34] mm: page_vma_mapped_walk(): prettify PVMW_MIGRATION block

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

[ Upstream commit e2e1d4076c77b3671cf8ce702535ae7dee3acf89 ]

page_vma_mapped_walk() cleanup: rearrange the !pmd_present() block to
follow the same "return not_found, return not_found, return true"
pattern as the block above it (note: returning not_found there is never
premature, since existence or prior existence of huge pmd guarantees
good alignment).

Link: https://lkml.kernel.org/r/378c8650-1488-2edf-9647-32a53cf2e21@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: 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 | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/mm/page_vma_mapped.c b/mm/page_vma_mapped.c
index 7e1db77b096a..e32ed7912923 100644
--- a/mm/page_vma_mapped.c
+++ b/mm/page_vma_mapped.c
@@ -194,24 +194,22 @@ bool page_vma_mapped_walk(struct page_vma_mapped_walk *pvmw)
 			if (pmd_page(pmde) != page)
 				return not_found(pvmw);
 			return true;
-		} else if (!pmd_present(pmde)) {
-			if (thp_migration_supported()) {
-				if (!(pvmw->flags & PVMW_MIGRATION))
-					return not_found(pvmw);
-				if (is_migration_entry(pmd_to_swp_entry(pmde))) {
-					swp_entry_t entry = pmd_to_swp_entry(pmde);
+		}
+		if (!pmd_present(pmde)) {
+			swp_entry_t entry;
 
-					if (migration_entry_to_page(entry) != page)
-						return not_found(pvmw);
-					return true;
-				}
-			}
-			return not_found(pvmw);
-		} else {
-			/* THP pmd was split under us: handle on pte level */
-			spin_unlock(pvmw->ptl);
-			pvmw->ptl = NULL;
+			if (!thp_migration_supported() ||
+			    !(pvmw->flags & PVMW_MIGRATION))
+				return not_found(pvmw);
+			entry = pmd_to_swp_entry(pmde);
+			if (!is_migration_entry(entry) ||
+			    migration_entry_to_page(entry) != page)
+				return not_found(pvmw);
+			return true;
 		}
+		/* THP pmd was split under us: handle on pte level */
+		spin_unlock(pvmw->ptl);
+		pvmw->ptl = NULL;
 	} else if (!pmd_present(pmde)) {
 		/*
 		 * If PVMW_SYNC, take and drop THP pmd lock so that we
-- 
2.30.2