Messages in this thread | | | Subject | Re: [PATCH v2] mm/page_isolation: don't putback unisolated page | From | David Hildenbrand <> | Date | Mon, 13 Sep 2021 14:15:25 +0200 |
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On 13.09.21 13:50, Miaohe Lin wrote: > If __isolate_free_page() failed, due to zone watermark check, the page is > still on the free list. But this page will be put back to free list again > via __putback_isolated_page() now. This may trigger page->flags checks in > __free_one_page() if PageReported is set. Or we will corrupt the free list > because list_add() will be called for pages already on another list. > > Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock") > Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> > --- > v1->v2: > Add VM_WARN_ON to catch unexpected isolating failure. > --- > mm/page_isolation.c | 9 +++++++-- > 1 file changed, 7 insertions(+), 2 deletions(-) > > diff --git a/mm/page_isolation.c b/mm/page_isolation.c > index f93cc63d8fa1..f67c4c70f17f 100644 > --- a/mm/page_isolation.c > +++ b/mm/page_isolation.c > @@ -94,8 +94,13 @@ static void unset_migratetype_isolate(struct page *page, unsigned migratetype) > buddy = page + (buddy_pfn - pfn); > > if (!is_migrate_isolate_page(buddy)) { > - __isolate_free_page(page, order); > - isolated_page = true; > + isolated_page = !!__isolate_free_page(page, order); > + /* > + * Isolating a free page in an isolated pageblock > + * is expected to always work as watermarks don't > + * apply here. > + */ > + VM_WARN_ON(!isolated_page);
Didn't we discuss that this can never happen?
In that case, the patch description+subject needs updating and the "Fixes" line would be wrong.
> } > } > } >
-- Thanks,
David / dhildenb
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