On 08/29/24 at 10:12am, Uladzislau Rezki wrote:
> On Thu, Aug 29, 2024 at 11:48:32AM +0800, Baoquan He wrote:
> > 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.
> >
> I agree. It sounds like hard to figure out the difference between both.
> Are you willing send the patch? If not, i can send it out :)
I am fine, please go ahead.
