Hi Minchan,
Thanks for reviewing.
On 2017/1/23 13:14, Minchan Kim wrote:
> Hello,
>
> On Thu, Jan 19, 2017 at 10:59:03PM +0800, ysxie@xxxxxxxxxxx wrote:
>> From: Yisheng Xie <xieyisheng1@xxxxxxxxxx>
>>
>> @@ -1527,7 +1527,8 @@ static int get_any_page(struct page *page, unsigned long pfn, int flags)
>> {
>> int ret = __get_any_page(page, pfn, flags);
>>
>> - if (ret == 1 && !PageHuge(page) && !PageLRU(page)) {
>> + if (ret == 1 && !PageHuge(page) &&
>> + !PageLRU(page) && !__PageMovable(page)) {
>
> __PageMovable without holding page_lock could be raced so need to check
> if it's okay to miss some of pages offlining by the race.
> When I read description of soft_offline_page, it seems to be okay.
> Just wanted double check. :)
Yes, I have thought about whether should add page_lock to avoid race. For it is ok to
miss some of pages caused by race, I do not add page_lock.
>
>> /*
>> * Try to free it.
>> */
>> @@ -1609,7 +1610,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
>>
>> static int __soft_offline_page(struct page *page, int flags)
>> {
>> - int ret;
>> + int ret = -1;
>> unsigned long pfn = page_to_pfn(page);
>>
>> /*
>> @@ -1619,7 +1620,8 @@ static int __soft_offline_page(struct page *page, int flags)
>> * so there's no race between soft_offline_page() and memory_failure().
>> */
>> lock_page(page);
>> - wait_on_page_writeback(page);
>> + if (PageLRU(page))
>> + wait_on_page_writeback(page);
>
> I doubt we need to add such limitation(i.e., Only LRU pages could be write-backed).
> Do you have some reason to add that code?
I add this check for not quite sure about whether non-lru page will as marked as
PageWriteBack(page). I will delete no need limitation in next version.
>
>> if (PageHWPoison(page)) {
>> unlock_page(page);
>> put_hwpoison_page(page);
>> @@ -1630,7 +1632,8 @@ static int __soft_offline_page(struct page *page, int flags)
>> * Try to invalidate first. This should work for
>> * non dirty unmapped page cache pages.
>> */
>> - ret = invalidate_inode_page(page);
>> + if (PageLRU(page))
>> + ret = invalidate_inode_page(page);
>
> Ditto.
>
>> unlock_page(page);
>> /*
>> * RED-PEN would be better to keep it isolated here, but we
>> @@ -1649,7 +1652,10 @@ static int __soft_offline_page(struct page *page, int flags)
>> * Try to migrate to a new page instead. migrate.c
>> * handles a large number of cases for us.
>> */
>> - ret = isolate_lru_page(page);
>> + if (PageLRU(page))
>> + ret = isolate_lru_page(page);
>> + else
>> + ret = !isolate_movable_page(page, ISOLATE_UNEVICTABLE);
>> /*
>> * Drop page reference which is came from get_any_page()
>> * successful isolate_lru_page() already took another one.
>> @@ -1657,18 +1663,15 @@ static int __soft_offline_page(struct page *page, int flags)
>> put_hwpoison_page(page);
>> if (!ret) {
>> LIST_HEAD(pagelist);
>> - inc_node_page_state(page, NR_ISOLATED_ANON +
>> + if (PageLRU(page))
>
> isolate_lru_page removes PG_lru so this check will be false. Namely, happens
> isolated count mismatch happens.
>
Really sorry about that. That's my mistake.
I will use !__PageMovable(page) instead in v3.
Thanks
Yisheng Xie.
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