On 2022/9/5 13:22, HORIGUCHI NAOYA(堀口 直也) wrote:
> Hi Miaohe,
>
> On Tue, Aug 30, 2022 at 08:36:00PM +0800, Miaohe Lin wrote:
>> It's more recommended to use __PageMovable() to detect non-lru movable
>> pages. We can avoid bumping page refcnt via isolate_movable_page() for
>> the isolated lru pages. Also if pages become PageLRU just after they're
>> checked but before trying to isolate them, isolate_lru_page() will be
>> called to do the right work.
>
> Good point, non-lru movable page is currently handled by isolate_lru_page(),
> which always fails. This means that we lost the chance of soft-offlining
> for any non-lru movable page. So this patch improves the situation.
Non-lru movable page will still be handled by isolate_movable_page() before the code change
as they don't have PageLRU set. The current situation is that the isolated LRU pages are
passed to isolate_movable_page() uncorrectly. This might not hurt. But the chance that pages
become un-isolated and thus available just after checking could be seized with this patch.
>
>>
>> Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
>> ---
>> mm/memory-failure.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
>> index a923a6dde871..3966fa6abe03 100644
>> --- a/mm/memory-failure.c
>> +++ b/mm/memory-failure.c
>> @@ -2404,7 +2404,7 @@ EXPORT_SYMBOL(unpoison_memory);
>> static bool isolate_page(struct page *page, struct list_head *pagelist)
>> {
>> bool isolated = false;
>> - bool lru = PageLRU(page);
>> + bool lru = !__PageMovable(page);
>
> It seems that PAGE_MAPPING_MOVABLE is not set for hugetlb pages, so
> lru becomes true for them. Then, if isolate_hugetlb() succeeds,
> inc_node_page_state() is called for hugetlb pages, maybe that's not expected.
Yes, that's unexpected. Thanks for pointing this out.
>
>>
>> if (PageHuge(page)) {
>> isolated = !isolate_hugetlb(page, pagelist);
> } else {
> if (lru)
> isolated = !isolate_lru_page(page);
> else
> isolated = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
>
> if (isolated)
> list_add(&page->lru, pagelist);
> }
>
> if (isolated && lru)
> inc_node_page_state(page, NR_ISOLATED_ANON +
> page_is_file_lru(page));
>
> so, how about moving this if block into the above else block?
> Then, the automatic variable lru can be moved into the else block.
Do you mean something like below?
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index df3bf266eebf..48780f3a61d3 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -2404,24 +2404,25 @@ EXPORT_SYMBOL(unpoison_memory);
static bool isolate_page(struct page *page, struct list_head *pagelist)
{
bool isolated = false;
- bool lru = !__PageMovable(page);
if (PageHuge(page)) {
isolated = !isolate_hugetlb(page, pagelist);
} else {
+ bool lru = !__PageMovable(page);
+
if (lru)
isolated = !isolate_lru_page(page);
else
isolated = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
- if (isolated)
+ if (isolated) {
list_add(&page->lru, pagelist);
+ if (lru)
+ inc_node_page_state(page, NR_ISOLATED_ANON +
+ page_is_file_lru(page));
+ }
}
- if (isolated && lru)
- inc_node_page_state(page, NR_ISOLATED_ANON +
- page_is_file_lru(page));
-
/*
* If we succeed to isolate the page, we grabbed another refcount on
* the page, so we can safely drop the one we got from get_any_pages().
>
> Thanks,
> Naoya Horiguchi
Thanks a lot for your review and comment on this series, Naoya.
Thanks,
Miaohe Lin.
