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Message-ID: <f987bc44-f28e-688d-2424-b4722153ed8@google.com>
Date: Tue, 8 Jun 2021 21:27:45 -0700 (PDT)
From: Hugh Dickins <hughd@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: Hugh Dickins <hughd@...gle.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Yang Shi <shy828301@...il.com>,
Wang Yugui <wangyugui@...-tech.com>,
Matthew Wilcox <willy@...radead.org>,
Naoya Horiguchi <naoya.horiguchi@....com>,
Alistair Popple <apopple@...dia.com>,
Ralph Campbell <rcampbell@...dia.com>, Zi Yan <ziy@...dia.com>,
Miaohe Lin <linmiaohe@...wei.com>,
Minchan Kim <minchan@...nel.org>, Jue Wang <juew@...gle.com>,
Peter Xu <peterx@...hat.com>, Jan Kara <jack@...e.cz>,
Shakeel Butt <shakeelb@...gle.com>,
Oscar Salvador <osalvador@...e.de>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 09/10] mm/thp: remap_page() is only needed on anonymous
THP
THP splitting's unmap_page() only sets TTU_SPLIT_FREEZE when PageAnon,
and migration entries are only inserted when TTU_MIGRATION (unused here)
or TTU_SPLIT_FREEZE is set: so it's just a waste of time for remap_page()
to search for migration entries to remove when !PageAnon.
Fixes: baa355fd3314 ("thp: file pages support for split_huge_page()")
Signed-off-by: Hugh Dickins <hughd@...gle.com>
Reviewed-by: Yang Shi <shy828301@...il.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
---
mm/huge_memory.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 6d2a0119fc58..319a1a078451 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2355,6 +2355,7 @@ static void unmap_page(struct page *page)
VM_BUG_ON_PAGE(!PageHead(page), page);
+ /* If TTU_SPLIT_FREEZE is ever extended to file, update remap_page() */
if (PageAnon(page))
ttu_flags |= TTU_SPLIT_FREEZE;
@@ -2366,6 +2367,10 @@ static void unmap_page(struct page *page)
static void remap_page(struct page *page, unsigned int nr)
{
int i;
+
+ /* If TTU_SPLIT_FREEZE is ever extended to file, remove this check */
+ if (!PageAnon(page))
+ return;
if (PageTransHuge(page)) {
remove_migration_ptes(page, page, true);
} else {
--
2.26.2
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