This is a note to let you know that I've just added the patch titled
mm/migrate: set swap entry values of THP tail pages properly.
to the 5.4-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-migrate-set-swap-entry-values-of-thp-tail-pages-properly.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From stable+bounces-26998-greg=kroah.com@xxxxxxxxxxxxxxx Wed Mar 6 16:51:22 2024
From: Zi Yan <zi.yan@xxxxxxxx>
Date: Wed, 6 Mar 2024 10:51:13 -0500
Subject: mm/migrate: set swap entry values of THP tail pages properly.
To: gregkh@xxxxxxxxxxxxxxxxxxx, stable@xxxxxxxxxxxxxxx
Cc: Zi Yan <ziy@xxxxxxxxxx>, linux-mm@xxxxxxxxx, Charan Teja Kalla <quic_charante@xxxxxxxxxxx>, "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>, David Hildenbrand <david@xxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, Huang Ying <ying.huang@xxxxxxxxx>, Naoya Horiguchi <naoya.horiguchi@xxxxxxxxx>
Message-ID: <20240306155113.118119-1-zi.yan@xxxxxxxx>
From: Zi Yan <ziy@xxxxxxxxxx>
The tail pages in a THP can have swap entry information stored in their
private field. When migrating to a new page, all tail pages of the new
page need to update ->private to avoid future data corruption.
This fix is stable-only, since after commit 07e09c483cbe ("mm/huge_memory:
work on folio->swap instead of page->private when splitting folio"),
subpages of a swapcached THP no longer requires the maintenance.
Adding THPs to the swapcache was introduced in commit
38d8b4e6bdc87 ("mm, THP, swap: delay splitting THP during swap out"),
where each subpage of a THP added to the swapcache had its own swapcache
entry and required the ->private field to point to the correct swapcache
entry. Later, when THP migration functionality was implemented in commit
616b8371539a6 ("mm: thp: enable thp migration in generic path"),
it initially did not handle the subpages of swapcached THPs, failing to
update their ->private fields or replace the subpage pointers in the
swapcache. Subsequently, commit e71769ae5260 ("mm: enable thp migration
for shmem thp") addressed the swapcache update aspect. This patch fixes
the update of subpage ->private fields.
Closes: https://lore.kernel.org/linux-mm/1707814102-22682-1-git-send-email-quic_charante@xxxxxxxxxxx/
Fixes: 616b8371539a ("mm: thp: enable thp migration in generic path")
Signed-off-by: Zi Yan <ziy@xxxxxxxxxx>
Acked-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/migrate.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -441,8 +441,12 @@ int migrate_page_move_mapping(struct add
if (PageSwapBacked(page)) {
__SetPageSwapBacked(newpage);
if (PageSwapCache(page)) {
+ int i;
+
SetPageSwapCache(newpage);
- set_page_private(newpage, page_private(page));
+ for (i = 0; i < (1 << compound_order(page)); i++)
+ set_page_private(newpage + i,
+ page_private(page + i));
}
} else {
VM_BUG_ON_PAGE(PageSwapCache(page), page);
Patches currently in stable-queue which might be from kroah.com@xxxxxxxxxxxxxxx are
queue-5.4/loop-factor-out-configuring-loop-from-status.patch
queue-5.4/loop-call-loop_config_discard-only-after-new-config-is-applied.patch
queue-5.4/loop-refactor-loop_set_status-size-calculation.patch
queue-5.4/loop-factor-out-setting-loop-device-size.patch
queue-5.4/loop-check-for-overflow-while-configuring-loop.patch
queue-5.4/loop-remove-sector_t-truncation-checks.patch
queue-5.4/revert-loop-check-for-overflow-while-configuring-loop.patch
queue-5.4/loop-loop_set_status_from_info-check-before-assignment.patch
queue-5.4/mm-migrate-set-swap-entry-values-of-thp-tail-pages-properly.patch
