This is a note to let you know that I've just added the patch titled
mm/memory_hotplug: use pfn math in place of direct struct page manipulation
to the 6.6-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-memory_hotplug-use-pfn-math-in-place-of-direct-struct-page-manipulation.patch
and it can be found in the queue-6.6 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 1640a0ef80f6d572725f5b0330038c18e98ea168 Mon Sep 17 00:00:00 2001
From: Zi Yan <ziy@xxxxxxxxxx>
Date: Wed, 13 Sep 2023 16:12:46 -0400
Subject: mm/memory_hotplug: use pfn math in place of direct struct page manipulation
From: Zi Yan <ziy@xxxxxxxxxx>
commit 1640a0ef80f6d572725f5b0330038c18e98ea168 upstream.
When dealing with hugetlb pages, manipulating struct page pointers
directly can get to wrong struct page, since struct page is not guaranteed
to be contiguous on SPARSEMEM without VMEMMAP. Use pfn calculation to
handle it properly.
Without the fix, a wrong number of page might be skipped. Since skip cannot be
negative, scan_movable_page() will end early and might miss a movable page with
-ENOENT. This might fail offline_pages(). No bug is reported. The fix comes
from code inspection.
Link: https://lkml.kernel.org/r/20230913201248.452081-4-zi.yan@xxxxxxxx
Fixes: eeb0efd071d8 ("mm,memory_hotplug: fix scan_movable_pages() for gigantic hugepages")
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Reviewed-by: Muchun Song <songmuchun@xxxxxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memory_hotplug.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1689,7 +1689,7 @@ static int scan_movable_pages(unsigned l
*/
if (HPageMigratable(head))
goto found;
- skip = compound_nr(head) - (page - head);
+ skip = compound_nr(head) - (pfn - page_to_pfn(head));
pfn += skip - 1;
}
return -ENOENT;
Patches currently in stable-queue which might be from ziy@xxxxxxxxxx are
queue-6.6/mm-memory_hotplug-use-pfn-math-in-place-of-direct-struct-page-manipulation.patch
queue-6.6/fs-use-nth_page-in-place-of-direct-struct-page-manipulation.patch
queue-6.6/mm-cma-use-nth_page-in-place-of-direct-struct-page-manipulation.patch
queue-6.6/mips-use-nth_page-in-place-of-direct-struct-page-manipulation.patch
queue-6.6/mm-hugetlb-use-nth_page-in-place-of-direct-struct-page-manipulation.patch
