On 08/27/24 at 09:09pm, Uladzislau Rezki (Sony) wrote:
> The aim is to simplify and making the vm_area_alloc_pages()
> function less confusing as it became more clogged nowadays:
>
> - eliminate a "bulk_gfp" variable and do not overwrite a gfp
> flag for bulk allocator;
> - drop __GFP_NOFAIL flag for high-order-page requests on upper
> layer. It becomes less spread between levels when it comes to
> __GFP_NOFAIL allocations;
> - add a comment about a fallback path if high-order attempt is
> unsuccessful because for such cases __GFP_NOFAIL is dropped;
> - fix a typo in a commit message.
>
> Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
> ---
> mm/vmalloc.c | 37 +++++++++++++++++--------------------
> 1 file changed, 17 insertions(+), 20 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 3f9b6bd707d2..57862865e808 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -3531,8 +3531,6 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
> unsigned int order, unsigned int nr_pages, struct page **pages)
> {
> unsigned int nr_allocated = 0;
> - gfp_t alloc_gfp = gfp;
> - bool nofail = gfp & __GFP_NOFAIL;
> struct page *page;
> int i;
>
> @@ -3543,9 +3541,6 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
> * more permissive.
> */
> if (!order) {
> - /* bulk allocator doesn't support nofail req. officially */
> - gfp_t bulk_gfp = gfp & ~__GFP_NOFAIL;
> -
> while (nr_allocated < nr_pages) {
> unsigned int nr, nr_pages_request;
>
> @@ -3563,12 +3558,11 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
> * but mempolicy wants to alloc memory by interleaving.
> */
> if (IS_ENABLED(CONFIG_NUMA) && nid == NUMA_NO_NODE)
> - nr = alloc_pages_bulk_array_mempolicy_noprof(bulk_gfp,
> + nr = alloc_pages_bulk_array_mempolicy_noprof(gfp,
> nr_pages_request,
> pages + nr_allocated);
> -
> else
> - nr = alloc_pages_bulk_array_node_noprof(bulk_gfp, nid,
> + nr = alloc_pages_bulk_array_node_noprof(gfp, nid,
> nr_pages_request,
> pages + nr_allocated);
>
> @@ -3582,30 +3576,24 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
> if (nr != nr_pages_request)
> break;
> }
> - } else if (gfp & __GFP_NOFAIL) {
> - /*
> - * Higher order nofail allocations are really expensive and
> - * potentially dangerous (pre-mature OOM, disruptive reclaim
> - * and compaction etc.
> - */
> - alloc_gfp &= ~__GFP_NOFAIL;
> }
>
> /* High-order pages or fallback path if "bulk" fails. */
> while (nr_allocated < nr_pages) {
> - if (!nofail && fatal_signal_pending(current))
> + if (!(gfp & __GFP_NOFAIL) && fatal_signal_pending(current))
> break;
>
> if (nid == NUMA_NO_NODE)
> - page = alloc_pages_noprof(alloc_gfp, order);
> + page = alloc_pages_noprof(gfp, order);
> else
> - page = alloc_pages_node_noprof(nid, alloc_gfp, order);
> + page = alloc_pages_node_noprof(nid, gfp, order);
> +
> if (unlikely(!page))
> break;
>
> /*
> * Higher order allocations must be able to be treated as
> - * indepdenent small pages by callers (as they can with
> + * independent small pages by callers (as they can with
> * small-page vmallocs). Some drivers do their own refcounting
> * on vmalloc_to_page() pages, some use page->mapping,
> * page->lru, etc.
> @@ -3666,7 +3654,16 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
> set_vm_area_page_order(area, page_shift - PAGE_SHIFT);
> page_order = vm_area_page_order(area);
>
> - area->nr_pages = vm_area_alloc_pages(gfp_mask | __GFP_NOWARN,
> + /*
> + * Higher order nofail allocations are really expensive and
~~~~~~~~~~~~
Seems we use both higher-order and high-order to describe the
non 0-order pages in many places. I personally would take high-order,
higher-order seems to be a little confusing because it's not explicit
what is compared with and lower.
Surely this is not an issue to this patch, I see a lot of 'higher order'
in kernel codes.
For this patch,
Reviewed-by: Baoquan He <bhe@xxxxxxxxxx>
> + * potentially dangerous (pre-mature OOM, disruptive reclaim
> + * and compaction etc.
> + *
> + * Please note, the __vmalloc_node_range_noprof() falls-back
> + * to order-0 pages if high-order attempt is unsuccessful.
> + */
> + area->nr_pages = vm_area_alloc_pages((page_order ?
> + gfp_mask & ~__GFP_NOFAIL : gfp_mask) | __GFP_NOWARN,
> node, page_order, nr_small_pages, area->pages);
>
> atomic_long_add(area->nr_pages, &nr_vmalloc_pages);
> --
> 2.39.2
>
