mm,hwpoison: return 0 if the page is already poisoned in soft-offline

Currently, there is an inconsistency when calling soft-offline from
different paths on a page that is already poisoned.

1) madvise:

        madvise_inject_error skips any poisoned page and continues
        the loop.
        If that was the only page to madvise, it returns 0.

2) /sys/devices/system/memory/:

        When calling soft_offline_page_store()->soft_offline_page(),
        we return -EBUSY in case the page is already poisoned.
        This is inconsistent with a) the above example and b)
        memory_failure, where we return 0 if the page was poisoned.

Fix this by dropping the PageHWPoison() check in madvise_inject_error, and
let soft_offline_page return 0 if it finds the page already poisoned.

Please, note that this represents a user-api change, since now the return
error when calling soft_offline_page_store()->soft_offline_page() will be
different.

Signed-off-by: Oscar Salvador <osalvador@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Naoya Horiguchi <naoya.horiguchi@nec.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Aristeu Rozanski <aris@ruivo.org>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Dmitry Yakunin <zeil@yandex-team.ru>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Oscar Salvador <osalvador@suse.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Tony Luck <tony.luck@intel.com>
Link: https://lkml.kernel.org/r/20200922135650.1634-12-osalvador@suse.de
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/madvise.c b/mm/madvise.c
index 0039bfe..68b761c 100644 (file)
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -896,11 +896,6 @@ static int madvise_inject_error(int behavior,
                 */
                size = page_size(compound_head(page));
 
-               if (PageHWPoison(page)) {
-                       put_page(page);
-                       continue;
-               }
-
                if (behavior == MADV_SOFT_OFFLINE) {
                        pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
                                 pfn, start);

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index 93b32d4..1fb290f 100644 (file)
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1802,7 +1802,7 @@ static int __soft_offline_page(struct page *page)
                unlock_page(page);
                put_page(page);
                pr_info("soft offline: %#lx page already poisoned\n", pfn);
-               return -EBUSY;
+               return 0;
        }
 
        if (!PageHuge(page))
@@ -1906,7 +1906,7 @@ int soft_offline_page(unsigned long pfn, int flags)
                pr_info("soft offline: %#lx page already poisoned\n", pfn);
                if (flags & MF_COUNT_INCREASED)
                        put_page(page);
-               return -EBUSY;
+               return 0;
        }
 
        get_online_mems();