+ mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch added to -mm tree

* + mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch added to -mm tree
@ 2020-04-29 23:59 akpm
  0 siblings, 0 replies; 2+ messages in thread
From: akpm @ 2020-04-29 23:59 UTC (permalink / raw)
  To: aarcange, hughd, kirill.shutemov, mm-commits, yang.shi


The patch titled
     Subject: mm: khugepaged: don't have to put being freed page back to lru
has been added to the -mm tree.  Its filename is
     mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch

This patch should soon appear at
    http://ozlabs.org/~akpm/mmots/broken-out/mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch
and later at
    http://ozlabs.org/~akpm/mmotm/broken-out/mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch

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------------------------------------------------------
From: Yang Shi <yang.shi@linux.alibaba.com>
Subject: mm: khugepaged: don't have to put being freed page back to lru

When khugepaged successfully isolated and copied data from base page to
collapsed THP, the base page is about to be freed.  So putting the page
back to lru sounds not that productive since the page might be isolated by
vmscan but it can't be reclaimed by vmscan since it can't be unmapped by
try_to_unmap() at all.

Actually khugepaged is the last user of this page so it can be freed
directly.  So clear active and unevictable flags, unlock and drop refcount
from isolate instead of calling putback_lru_page().

Link: http://lkml.kernel.org/r/1588200982-69492-2-git-send-email-yang.shi@linux.alibaba.com
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/khugepaged.c |   15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

--- a/mm/khugepaged.c~mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru
+++ a/mm/khugepaged.c
@@ -559,6 +559,17 @@ void __khugepaged_exit(struct mm_struct
 static void release_pte_page(struct page *page)
 {
 	mod_node_page_state(page_pgdat(page),
+		NR_ISOLATED_ANON + page_is_file_lru(page), -compound_nr(page));
+	ClearPageActive(page);
+	ClearPageUnevictable(page);
+	unlock_page(page);
+	/* Drop refcount from isolate */
+	put_page(page);
+}
+
+static void release_pte_page_to_lru(struct page *page)
+{
+	mod_node_page_state(page_pgdat(page),
 			NR_ISOLATED_ANON + page_is_file_lru(page),
 			-compound_nr(page));
 	unlock_page(page);
@@ -576,12 +587,12 @@ static void release_pte_pages(pte_t *pte
 		page = pte_page(pteval);
 		if (!pte_none(pteval) && !is_zero_pfn(pte_pfn(pteval)) &&
 				!PageCompound(page))
-			release_pte_page(page);
+			release_pte_page_to_lru(page);
 	}
 
 	list_for_each_entry_safe(page, tmp, compound_pagelist, lru) {
 		list_del(&page->lru);
-		release_pte_page(page);
+		release_pte_page_to_lru(page);
 	}
 }
 
_

Patches currently in -mm which might be from yang.shi@linux.alibaba.com are

mm-khugepaged-add-exceed_max_ptes_-helpers.patch
mm-khugepaged-dont-have-to-put-being-freed-page-back-to-lru.patch
mm-thp-dont-need-drain-lru-cache-when-splitting-and-mlocking-thp.patch

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