The patch titled
Subject: mm/hugetlb: correct demote page offset logic
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-hugetlb-correct-demote-page-offset-logic.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hugetlb-correct-demote-page-offset-logic.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Doug Berger <opendmb@xxxxxxxxx>
Subject: mm/hugetlb: correct demote page offset logic
Date: Wed, 14 Sep 2022 12:09:17 -0700
With gigantic pages it may not be true that struct page structures are
contiguous across the entire gigantic page. The nth_page macro is used
here in place of direct pointer arithmetic to correct for this.
Link: https://lkml.kernel.org/r/20220914190917.3517663-1-opendmb@xxxxxxxxx
Fixes: 8531fc6f52f5 ("hugetlb: add hugetlb demote page support")
Signed-off-by: Doug Berger <opendmb@xxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/hugetlb.c | 14 ++++++++------
1 file changed, 8 insertions(+), 6 deletions(-)
--- a/mm/hugetlb.c~mm-hugetlb-correct-demote-page-offset-logic
+++ a/mm/hugetlb.c
@@ -3420,6 +3420,7 @@ static int demote_free_huge_page(struct
{
int i, nid = page_to_nid(page);
struct hstate *target_hstate;
+ struct page *subpage;
int rc = 0;
target_hstate = size_to_hstate(PAGE_SIZE << h->demote_order);
@@ -3453,15 +3454,16 @@ static int demote_free_huge_page(struct
mutex_lock(&target_hstate->resize_lock);
for (i = 0; i < pages_per_huge_page(h);
i += pages_per_huge_page(target_hstate)) {
+ subpage = nth_page(page, i);
if (hstate_is_gigantic(target_hstate))
- prep_compound_gigantic_page_for_demote(page + i,
+ prep_compound_gigantic_page_for_demote(subpage,
target_hstate->order);
else
- prep_compound_page(page + i, target_hstate->order);
- set_page_private(page + i, 0);
- set_page_refcounted(page + i);
- prep_new_huge_page(target_hstate, page + i, nid);
- put_page(page + i);
+ prep_compound_page(subpage, target_hstate->order);
+ set_page_private(subpage, 0);
+ set_page_refcounted(subpage);
+ prep_new_huge_page(target_hstate, subpage, nid);
+ put_page(subpage);
}
mutex_unlock(&target_hstate->resize_lock);
_
Patches currently in -mm which might be from opendmb@xxxxxxxxx are
mm-hugetlb-correct-demote-page-offset-logic.patch
