[to-be-updated] madvise-madvise_cold_or_pageout_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch removed from -mm tree

[to-be-updated] madvise-madvise_cold_or_pageout_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch removed from -mm tree

[Andrew Morton]

The quilt patch titled
     Subject: madvise:madvise_cold_or_pageout_pte_range(): don't use mapcount() against large folio for sharing check
has been removed from the -mm tree.  Its filename was
     madvise-madvise_cold_or_pageout_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch

This patch was dropped because an updated version will be merged

------------------------------------------------------
From: Yin Fengwei <fengwei.yin@intel.com>
Subject: madvise:madvise_cold_or_pageout_pte_range(): don't use mapcount() against large folio for sharing check
Date: Sat, 29 Jul 2023 00:13:55 +0800

Patch series "don't use mapcount() to check large folio sharing".

In madvise_cold_or_pageout_pte_range() and madvise_free_pte_range(),
folio_mapcount() is used to check whether the folio is shared.  But it's
not correct as folio_mapcount() returns total mapcount of large folio.

Use folio_estimated_sharers() here as the estimated number is enough.


This patch (of 3):

Commit 07e8c82b5eff ("madvise: convert madvise_cold_or_pageout_pte_range()
to use folios") replaced the page_mapcount() with folio_mapcount() to
check whether the folio is shared by other mapping.

But it's not correct for large folio.  folio_mapcount() returns the total
mapcount of large folio which is not suitable to detect whether the folio
is shared.

Use folio_estimated_sharers() which returns a estimated number of shares. 
That means it's not 100% correct.  But it should be OK for madvise case
here.

Link: https://lkml.kernel.org/r/20230728161356.1784568-1-fengwei.yin@intel.com
Link: https://lkml.kernel.org/r/20230728161356.1784568-2-fengwei.yin@intel.com
Fixes: 07e8c82b5eff ("madvise: convert madvise_cold_or_pageout_pte_range() to use folios")
Signed-off-by: Yin Fengwei <fengwei.yin@intel.com>
Reviewed-by: Yu Zhao <yuzhao@google.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/madvise.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/mm/madvise.c~madvise-madvise_cold_or_pageout_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check
+++ a/mm/madvise.c
@@ -384,7 +384,7 @@ static int madvise_cold_or_pageout_pte_r
 		folio = pfn_folio(pmd_pfn(orig_pmd));
 
 		/* Do not interfere with other mappings of this folio */
-		if (folio_mapcount(folio) != 1)
+		if (folio_estimated_sharers(folio) != 1)
 			goto huge_unlock;
 
 		if (pageout_anon_only_filter && !folio_test_anon(folio))
@@ -460,7 +460,7 @@ regular_folio:
 		if (folio_test_large(folio)) {
 			int err;
 
-			if (folio_mapcount(folio) != 1)
+			if (folio_estimated_sharers(folio) != 1)
 				break;
 			if (pageout_anon_only_filter && !folio_test_anon(folio))
 				break;
_

Patches currently in -mm which might be from fengwei.yin@intel.com are

madvise-madvise_free_huge_pmd-dont-use-mapcount-against-large-folio-for-sharing-check.patch
madvise-madvise_free_pte_range-dont-use-mapcount-against-large-folio-for-sharing-check.patch
filemap-add-filemap_map_folio_range.patch
rmap-add-folio_add_file_rmap_range.patch
mm-convert-do_set_pte-to-set_pte_range.patch
filemap-batch-pte-mappings.patch