+ mm-migrate_device-try-to-handle-swapcache-pages.patch added to mm-unstable branch

+ mm-migrate_device-try-to-handle-swapcache-pages.patch added to mm-unstable branch

[Andrew Morton]

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The patch titled
     Subject: mm/migrate_device: try to handle swapcache pages
has been added to the -mm mm-unstable branch.  Its filename is
     mm-migrate_device-try-to-handle-swapcache-pages.patch

This patch will shortly appear at
     https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-migrate_device-try-to-handle-swapcache-pages.patch

This patch will later appear in the mm-unstable branch at
    git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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------------------------------------------------------
From: Mika Penttilä <mpenttil@redhat.com>
Subject: mm/migrate_device: try to handle swapcache pages
Date: Wed, 7 Jun 2023 20:29:44 +0300

Migrating file pages and swapcache pages into device memory is not
supported.  Try to get rid of the swap cache, and if successful, go ahead
as with other anonymous pages.

Link: https://lkml.kernel.org/r/20230607172944.11713-1-mpenttil@redhat.com
Signed-off-by: Mika Penttilä <mpenttil@redhat.com>
Reviewed-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 mm/migrate_device.c |   21 +++++++++++++++------
 1 file changed, 15 insertions(+), 6 deletions(-)

--- a/mm/migrate_device.c~mm-migrate_device-try-to-handle-swapcache-pages
+++ a/mm/migrate_device.c
@@ -727,13 +727,22 @@ static void __migrate_device_pages(unsig
 
 		if (is_device_private_page(newpage) ||
 		    is_device_coherent_page(newpage)) {
-			/*
-			 * For now only support anonymous memory migrating to
-			 * device private or coherent memory.
-			 */
 			if (mapping) {
-				src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
-				continue;
+				struct folio *folio;
+
+				folio = page_folio(page);
+
+				/*
+				 * For now only support anonymous memory migrating to
+				 * device private or coherent memory.
+				 *
+				 * Try to get rid of swap cache if possible.
+				 */
+				if (!folio_test_anon(folio) ||
+				    !folio_free_swap(folio)) {
+					src_pfns[i] &= ~MIGRATE_PFN_MIGRATE;
+					continue;
+				}
 			}
 		} else if (is_zone_device_page(newpage)) {
 			/*
_

Patches currently in -mm which might be from mpenttil@redhat.com are

mm-migrate_device-try-to-handle-swapcache-pages.patch