Re: [PATCH 03/10] soft-offline: use migrate_pages() instead of migrate_huge_page()

[Aneesh Kumar K.V]

Michal Hocko <mhocko@xxxxxxx> writes:

> On Tue 26-03-13 16:59:40, Aneesh Kumar K.V wrote:
>> Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> writes:
> [...]
>> > diff --git v3.9-rc3.orig/mm/memory-failure.c v3.9-rc3/mm/memory-failure.c
>> > index df0694c..4e01082 100644
>> > --- v3.9-rc3.orig/mm/memory-failure.c
>> > +++ v3.9-rc3/mm/memory-failure.c
>> > @@ -1467,6 +1467,7 @@ static int soft_offline_huge_page(struct page *page, int flags)
>> >  	int ret;
>> >  	unsigned long pfn = page_to_pfn(page);
>> >  	struct page *hpage = compound_head(page);
>> > +	LIST_HEAD(pagelist);
>> >
>> >  	/*
>> >  	 * This double-check of PageHWPoison is to avoid the race with
>> > @@ -1482,12 +1483,20 @@ static int soft_offline_huge_page(struct page *page, int flags)
>> >  	unlock_page(hpage);
>> >
>> >  	/* Keep page count to indicate a given hugepage is isolated. */
>> > -	ret = migrate_huge_page(hpage, new_page, MPOL_MF_MOVE_ALL,
>> > -				MIGRATE_SYNC);
>> > -	put_page(hpage);
>> > +	list_move(&hpage->lru, &pagelist);
>> 
>> we use hpage->lru to add the hpage to h->hugepage_activelist. This will
>> break a hugetlb cgroup removal isn't it ?
>
> This particular part will not break removal because
> hugetlb_cgroup_css_offline loops until hugetlb_cgroup_have_usage is 0.
>

But we still need to hold hugetlb_lock around that right ?

-aneesh

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