On Mon 05-04-21 16:00:39, Mike Kravetz wrote:
> The new remove_hugetlb_page() routine is designed to remove a hugetlb
> page from hugetlbfs processing. It will remove the page from the active
> or free list, update global counters and set the compound page
> destructor to NULL so that PageHuge() will return false for the 'page'.
> After this call, the 'page' can be treated as a normal compound page or
> a collection of base size pages.
>
> update_and_free_page no longer decrements h->nr_huge_pages{_node} as
> this is performed in remove_hugetlb_page. The only functionality
> performed by update_and_free_page is to free the base pages to the lower
> level allocators.
>
> update_and_free_page is typically called after remove_hugetlb_page.
>
> remove_hugetlb_page is to be called with the hugetlb_lock held.
>
> Creating this routine and separating functionality is in preparation for
> restructuring code to reduce lock hold times. This commit should not
> introduce any changes to functionality.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx>
Btw. I would prefer to reverse the ordering of this and Oscar's
patchset. This one is a bug fix which might be interesting for stable
backports while Oscar's work can be looked as a general functionality
improvement.
> @@ -2298,6 +2312,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> /*
> * Freed from under us. Drop new_page too.
> */
> + remove_hugetlb_page(h, new_page, false);
> update_and_free_page(h, new_page);
> goto unlock;
> } else if (page_count(old_page)) {
> @@ -2305,6 +2320,7 @@ static int alloc_and_dissolve_huge_page(struct hstate *h, struct page *old_page,
> * Someone has grabbed the page, try to isolate it here.
> * Fail with -EBUSY if not possible.
> */
> + remove_hugetlb_page(h, new_page, false);
> update_and_free_page(h, new_page);
> spin_unlock(&hugetlb_lock);
> if (!isolate_huge_page(old_page, list))
the page is not enqued anywhere here so remove_hugetlb_page would blow
when linked list debugging is enabled.
--
Michal Hocko
SUSE Labs
