Messages in this thread | | | Date | Wed, 6 Sep 2023 15:38:16 +0800 | Subject | Re: [PATCH v2 08/11] hugetlb: batch freeing of vmemmap pages | From | Muchun Song <> |
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On 2023/9/6 05:44, Mike Kravetz wrote: > Now that batching of hugetlb vmemmap optimization processing is possible, > batch the freeing of vmemmap pages. When freeing vmemmap pages for a > hugetlb page, we add them to a list that is freed after the entire batch > has been processed. > > This enhances the ability to return contiguous ranges of memory to the > low level allocators. > > Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com> > --- > mm/hugetlb_vmemmap.c | 60 ++++++++++++++++++++++++++++---------------- > 1 file changed, 38 insertions(+), 22 deletions(-) > > diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c > index 79de984919ef..a715712df831 100644 > --- a/mm/hugetlb_vmemmap.c > +++ b/mm/hugetlb_vmemmap.c > @@ -306,18 +306,21 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, > * @end: end address of the vmemmap virtual address range that we want to > * remap. > * @reuse: reuse address. > + * @vmemmap_pages: list to deposit vmemmap pages to be freed. It is callers > + * responsibility to free pages. > * > * Return: %0 on success, negative error code otherwise. > */ > static int vmemmap_remap_free(unsigned long start, unsigned long end, > - unsigned long reuse) > + unsigned long reuse, > + struct list_head *vmemmap_pages) > { > int ret; > - LIST_HEAD(vmemmap_pages); > + LIST_HEAD(freed_pages);
IIUC, we could reuse the parameter of @vmemmap_pages directly instead of a temporary variable, could it be dropped?
> struct vmemmap_remap_walk walk = { > .remap_pte = vmemmap_remap_pte, > .reuse_addr = reuse, > - .vmemmap_pages = &vmemmap_pages, > + .vmemmap_pages = &freed_pages, > }; > int nid = page_to_nid((struct page *)start); > gfp_t gfp_mask = GFP_KERNEL | __GFP_THISNODE | __GFP_NORETRY | > @@ -335,7 +338,7 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, > if (walk.reuse_page) { > copy_page(page_to_virt(walk.reuse_page), > (void *)walk.reuse_addr); > - list_add(&walk.reuse_page->lru, &vmemmap_pages); > + list_add(&walk.reuse_page->lru, &freed_pages); > } > > /* > @@ -366,15 +369,14 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, > walk = (struct vmemmap_remap_walk) { > .remap_pte = vmemmap_restore_pte, > .reuse_addr = reuse, > - .vmemmap_pages = &vmemmap_pages, > + .vmemmap_pages = &freed_pages, > }; > > vmemmap_remap_range(reuse, end, &walk); > } > mmap_read_unlock(&init_mm); > > - free_vmemmap_page_list(&vmemmap_pages); > - > + list_splice(&freed_pages, vmemmap_pages); > return ret; > } > > @@ -553,17 +555,9 @@ static bool vmemmap_should_optimize(const struct hstate *h, const struct page *h > return true; > } > > -/** > - * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages. > - * @h: struct hstate. > - * @head: the head page whose vmemmap pages will be optimized. > - * > - * This function only tries to optimize @head's vmemmap pages and does not > - * guarantee that the optimization will succeed after it returns. The caller > - * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages > - * have been optimized. > - */ > -void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) > +static void __hugetlb_vmemmap_optimize(const struct hstate *h, > + struct page *head, > + struct list_head *vmemmap_pages) > { > unsigned long vmemmap_start = (unsigned long)head, vmemmap_end; > unsigned long vmemmap_reuse; > @@ -580,21 +574,43 @@ void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) > > /* > * Remap the vmemmap virtual address range [@vmemmap_start, @vmemmap_end) > - * to the page which @vmemmap_reuse is mapped to, then free the pages > - * which the range [@vmemmap_start, @vmemmap_end] is mapped to. > + * to the page which @vmemmap_reuse is mapped to. Add pages previously > + * mapping the range to vmemmap_pages list so that they can be freed by > + * the caller. > */ > - if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse)) > + if (vmemmap_remap_free(vmemmap_start, vmemmap_end, vmemmap_reuse, vmemmap_pages)) > static_branch_dec(&hugetlb_optimize_vmemmap_key); > else > SetHPageVmemmapOptimized(head); > } > > +/** > + * hugetlb_vmemmap_optimize - optimize @head page's vmemmap pages. > + * @h: struct hstate. > + * @head: the head page whose vmemmap pages will be optimized. > + * > + * This function only tries to optimize @head's vmemmap pages and does not > + * guarantee that the optimization will succeed after it returns. The caller > + * can use HPageVmemmapOptimized(@head) to detect if @head's vmemmap pages > + * have been optimized. > + */ > +void hugetlb_vmemmap_optimize(const struct hstate *h, struct page *head) > +{ > + LIST_HEAD(vmemmap_pages); > + > + __hugetlb_vmemmap_optimize(h, head, &vmemmap_pages); > + free_vmemmap_page_list(&vmemmap_pages); > +} > + > void hugetlb_vmemmap_optimize_folios(struct hstate *h, struct list_head *folio_list) > { > struct folio *folio; > + LIST_HEAD(vmemmap_pages); > > list_for_each_entry(folio, folio_list, lru) > - hugetlb_vmemmap_optimize(h, &folio->page); > + __hugetlb_vmemmap_optimize(h, &folio->page, &vmemmap_pages); > + > + free_vmemmap_page_list(&vmemmap_pages); > } > > static struct ctl_table hugetlb_vmemmap_sysctls[] = {
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