mm,hwpoison: return -EBUSY when migration fails

mainline inclusion
from mainline-v5.11-rc1
commit 3f4b815a
category: bugfix
bugzilla: 55077
CVE: NA

During LTP test, testcase 'move_pages12' failed. This is because
__soft_offline_page() will return -EIO when fail to migrate page.
This is not an error for 'move_pages12' but LTP treats 'return -EIO'
as an error.

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3f4b815a439adfb8f238335612c4b28bc10084d8

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

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: NZheng Zengkai <zhengzengkai@huawei.com>

mm/memory-failure.c

@@ -1851,11 +1851,11 @@ static int __soft_offline_page(struct page *page)
 			pr_info("soft offline: %#lx: %s migration failed %d, type %lx (%pGp)\n",
 				pfn, msg_page[huge], ret, page->flags, &page->flags);
 			if (ret > 0)
-				ret = -EIO;
+				ret = -EBUSY;
 		}
 	} else {
-		pr_info("soft offline: %#lx: %s isolation failed: %d, page count %d, type %lx (%pGp)\n",
-			pfn, msg_page[huge], ret, page_count(page), page->flags, &page->flags);
+		pr_info("soft offline: %#lx: %s isolation failed, page count %d, type %lx (%pGp)\n",
+			pfn, msg_page[huge], page_count(page), page->flags, &page->flags);
 		ret = -EBUSY;
 	}
 	return ret;