[RFC PATCH v2 14/16] mm,hwpoison: Return 0 if the page is already poisoned in soft-offline

From: Oscar Salvador
Date: Thu Oct 17 2019 - 10:21:53 EST


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/:

Whe 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 an 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@xxxxxxx>
---
mm/madvise.c | 3 ---
mm/memory-failure.c | 4 ++--
2 files changed, 2 insertions(+), 5 deletions(-)

diff --git a/mm/madvise.c b/mm/madvise.c
index 8a0b1f901d72..9ca48345ce45 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -887,9 +887,6 @@ 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 a/mm/memory-failure.c b/mm/memory-failure.c
index 3d491c0d3f91..c038896bedf0 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1767,7 +1767,7 @@ 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))
@@ -1866,7 +1866,7 @@ int soft_offline_page(struct page *page)

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

get_online_mems();
--
2.12.3