6.1-stable patches

added patches:
	madvise-madvise_free_pte_range-don-t-use-mapcount-against-large-folio-for-sharing-check.patch

diff --git a/queue-6.1/madvise-madvise_free_pte_range-don-t-use-mapcount-against-large-folio-for-sharing-check.patch b/queue-6.1/madvise-madvise_free_pte_range-don-t-use-mapcount-against-large-folio-for-sharing-check.patch
new file mode 100644 (file)
index 0000000..8a94aeb
--- /dev/null
+++ b/queue-6.1/madvise-madvise_free_pte_range-don-t-use-mapcount-against-large-folio-for-sharing-check.patch
@@ -0,0 +1,86 @@
+From 0e0e9bd5f7b9d40fd03b70092367247d52da1db0 Mon Sep 17 00:00:00 2001
+From: Yin Fengwei <fengwei.yin@intel.com>
+Date: Tue, 8 Aug 2023 10:09:17 +0800
+Subject: madvise:madvise_free_pte_range(): don't use mapcount() against large folio for sharing check
+
+From: Yin Fengwei <fengwei.yin@intel.com>
+
+commit 0e0e9bd5f7b9d40fd03b70092367247d52da1db0 upstream.
+
+Commit 98b211d6415f ("madvise: convert madvise_free_pte_range() to use a
+folio") replaced the page_mapcount() with folio_mapcount() to check
+whether the folio is shared by other mapping.
+
+It's not correct for large folios. 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. It should be OK for madvise case here.
+
+User-visible effects is that the THP is skipped when user call madvise.
+But the correct behavior is THP should be split and processed then.
+
+NOTE: this change is a temporary fix to reduce the user-visible effects
+before the long term fix from David is ready.
+
+Link: https://lkml.kernel.org/r/20230808020917.2230692-4-fengwei.yin@intel.com
+Fixes: 98b211d6415f ("madvise: convert madvise_free_pte_range() to use a folio")
+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 <willy@infradead.org>
+Cc: Minchan Kim <minchan@kernel.org>
+Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
+Cc: Yang Shi <shy828301@gmail.com>
+Cc: <stable@vger.kernel.org>
+Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ include/linux/mm.h |   19 +++++++++++++++++++
+ mm/madvise.c       |    4 ++--
+ 2 files changed, 21 insertions(+), 2 deletions(-)
+
+--- a/include/linux/mm.h
++++ b/include/linux/mm.h
+@@ -1727,6 +1727,25 @@ static inline size_t folio_size(struct f
+       return PAGE_SIZE << folio_order(folio);
+ }
+ 
++/**
++ * folio_estimated_sharers - Estimate the number of sharers of a folio.
++ * @folio: The folio.
++ *
++ * folio_estimated_sharers() aims to serve as a function to efficiently
++ * estimate the number of processes sharing a folio. This is done by
++ * looking at the precise mapcount of the first subpage in the folio, and
++ * assuming the other subpages are the same. This may not be true for large
++ * folios. If you want exact mapcounts for exact calculations, look at
++ * page_mapcount() or folio_total_mapcount().
++ *
++ * Return: The estimated number of processes sharing a folio.
++ */
++static inline int folio_estimated_sharers(struct folio *folio)
++{
++      return page_mapcount(folio_page(folio, 0));
++}
++
++
+ #ifndef HAVE_ARCH_MAKE_PAGE_ACCESSIBLE
+ static inline int arch_make_page_accessible(struct page *page)
+ {
+--- a/mm/madvise.c
++++ b/mm/madvise.c
+@@ -654,8 +654,8 @@ static int madvise_free_pte_range(pmd_t
+                * deactivate all pages.
+                */
+               if (folio_test_large(folio)) {
+-                      if (folio_mapcount(folio) != 1)
+-                              goto out;
++                      if (folio_estimated_sharers(folio) != 1)
++                              break;
+                       folio_get(folio);
+                       if (!folio_trylock(folio)) {
+                               folio_put(folio);

diff --git a/queue-6.1/series b/queue-6.1/series
index e1a148444646526016b8aab376566c1159958471..33aa8f1addbe40e2d717539d5dfc96b41dd38aa0 100644 (file)
--- a/queue-6.1/series
+++ b/queue-6.1/series
@@ -111,3 +111,4 @@ cgroup-cpuset-free-dl-bw-in-case-can_attach-fails.patch
 thunderbolt-fix-thunderbolt-3-display-flickering-issue-on-2nd-hot-plug-onwards.patch
 ublk-remove-check-io_uring_f_sqe128-in-ublk_ch_uring_cmd.patch
 can-raw-add-missing-refcount-for-memory-leak-fix.patch
+madvise-madvise_free_pte_range-don-t-use-mapcount-against-large-folio-for-sharing-check.patch