mm,hwpoison: return -EBUSY when migration fails

mainline inclusion
from mainline-v5.11-rc1
commit 3f4b815a
category: bugfix
bugzilla: NA
CVE: NA

-------------------------------------------------

Currently, we return -EIO when we fail to migrate the page.

Migrations' failures are rather transient as they can happen due to
several reasons, e.g: high page refcount bump, mapping->migrate_page
failing etc.  All meaning that at that time the page could not be
migrated, but that has nothing to do with an EIO error.

Let us return -EBUSY instead, as we do in case we failed to isolate the
page.

While are it, let us remove the "ret" print as its value does not change.

Link: https://lkml.kernel.org/r/20201209092818.30417-1-osalvador@suse.deSigned-off-by: NOscar Salvador <osalvador@suse.de>
Acked-by: NNaoya Horiguchi <naoya.horiguchi@nec.com>
Acked-by: NVlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NShixin Liu <liushixin2@huawei.com>
Reviewed-by: NKefeng Wang <wangkefeng.wang@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>

mm/memory-failure.c

@@ -1730,7 +1730,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
 		if (!list_empty(&pagelist))
 			putback_movable_pages(&pagelist);
 		if (ret > 0)
-			ret = -EIO;
+			ret = -EBUSY;
 	} else {
 		/*
 		 * We set PG_hwpoison only when the migration source hugepage
@@ -1821,11 +1821,11 @@ static int __soft_offline_page(struct page *page, int flags)
 			pr_info("soft offline: %#lx: migration failed %d, type %lx (%pGp)\n",
 				pfn, ret, page->flags, &page->flags);
 			if (ret > 0)
-				ret = -EIO;
+				ret = -EBUSY;
 		}
 	} else {
-		pr_info("soft offline: %#lx: isolation failed: %d, page count %d, type %lx (%pGp)\n",
-			pfn, ret, page_count(page), page->flags, &page->flags);
+		pr_info("soft offline: %#lx: isolation failed, page count %d, type %lx (%pGp)\n",
+			pfn, page_count(page), page->flags, &page->flags);
 	}
 	return ret;
 }