[PATCH v3 14/15] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline

nao.horiguchi
2020-06-24T15:02:38Z

From: Oscar Salvador <osalvador@suse.de>

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: Naoya Horiguchi <naoya.horiguchi@nec.com>
---
mm/madvise.c | 3 ---
mm/memory-failure.c | 4 ++--
2 files changed, 2 insertions(+), 5 deletions(-)

diff --git v5.8-rc1-mmots-2020-06-20-21-44/mm/madvise.c v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/madvise.c
index 2b5080253406..b59bbd6c9982 100644
--- v5.8-rc1-mmots-2020-06-20-21-44/mm/madvise.c
+++ v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/madvise.c
@@ -902,9 +902,6 @@ static int madvise_inject_error(int behavior,
*/
put_page(page);

- if (PageHWPoison(page))
- continue;
-
if (behavior == MADV_SOFT_OFFLINE) {
pr_info("Soft offlining pfn %#lx at process virtual address %#lx\n",
pfn, start);
diff --git v5.8-rc1-mmots-2020-06-20-21-44/mm/memory-failure.c v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/memory-failure.c
index 22c904f6d17a..9ad3198a3954 100644
--- v5.8-rc1-mmots-2020-06-20-21-44/mm/memory-failure.c
+++ v5.8-rc1-mmots-2020-06-20-21-44_patched/mm/memory-failure.c
@@ -1800,7 +1800,7 @@ 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))
@@ -1901,7 +1901,7 @@ int soft_offline_page(unsigned long pfn)

if (PageHWPoison(page)) {
pr_info("soft offline: %#lx page already poisoned\n", pfn);
- return -EBUSY;
+ return 0;
}

get_online_mems();
--
2.17.1