Messages in this thread | | | Date | Tue, 12 Feb 2019 09:33:29 +0100 | From | Michal Hocko <> | Subject | Re: [PATCH] mm,memory_hotplug: Explicitly pass the head to isolate_huge_page |
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On Fri 08-02-19 10:06:04, Oscar Salvador wrote: > isolate_huge_page() expects we pass the head of hugetlb page to it: > > bool isolate_huge_page(...) > { > ... > VM_BUG_ON_PAGE(!PageHead(page), page); > ... > } > > While I really cannot think of any situation where we end up with a > non-head page between hands in do_migrate_range(), let us make sure > the code is as sane as possible by explicitly passing the Head. > Since we already got the pointer, it does not take us extra effort. > > Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Btw.
> --- > mm/memory_hotplug.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index 656ff386ac15..d5f7afda67db 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -1378,12 +1378,12 @@ do_migrate_range(unsigned long start_pfn, unsigned long end_pfn) > > if (PageHuge(page)) { > struct page *head = compound_head(page); > - pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1; > if (compound_order(head) > PFN_SECTION_SHIFT) { > ret = -EBUSY; > break; > }
Why are we doing this, btw?
> - isolate_huge_page(page, &source); > + pfn = page_to_pfn(head) + (1<<compound_order(head)) - 1; > + isolate_huge_page(head, &source); > continue; > } else if (PageTransHuge(page)) > pfn = page_to_pfn(compound_head(page)) > -- > 2.13.7
-- Michal Hocko SUSE Labs
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