From: Uladzislau Rezki <urezki@xxxxxxxxx> Subject: mm/vmalloc: fallback to a single page allocator Currently for order-0 pages we use a bulk-page allocator to get set of pages. From the other hand not allocating all pages is something that might occur. In that case we should fallbak to the single-page allocator trying to get missing pages, because it is more permissive(direct reclaim, etc). Introduce a vm_area_alloc_pages() function where the described logic is implemented. Link: https://lkml.kernel.org/r/20210521130718.GA17882@xxxxxxxxx Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx> Reviewed-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Cc: Nicholas Piggin <npiggin@xxxxxxxxx> Cc: Hillf Danton <hdanton@xxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Oleksiy Avramchenko <oleksiy.avramchenko@xxxxxxxxxxxxxx> Cc: Steven Rostedt <rostedt@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/vmalloc.c | 81 +++++++++++++++++++++++++++++++------------------ 1 file changed, 52 insertions(+), 29 deletions(-) --- a/mm/vmalloc.c~mm-vmalloc-fallback-to-a-single-page-allocator +++ a/mm/vmalloc.c @@ -2758,6 +2758,54 @@ void *vmap_pfn(unsigned long *pfns, unsi EXPORT_SYMBOL_GPL(vmap_pfn); #endif /* CONFIG_VMAP_PFN */ +static inline unsigned int +vm_area_alloc_pages(gfp_t gfp, int nid, + unsigned int order, unsigned long nr_pages, struct page **pages) +{ + unsigned int nr_allocated = 0; + + /* + * For order-0 pages we make use of bulk allocator, if + * the page array is partly or not at all populated due + * to fails, fallback to a single page allocator that is + * more permissive. + */ + if (!order) + nr_allocated = alloc_pages_bulk_array_node( + gfp, nid, nr_pages, pages); + else + /* + * Compound pages required for remap_vmalloc_page if + * high-order pages. + */ + gfp |= __GFP_COMP; + + /* High-order pages or fallback path if "bulk" fails. */ + while (nr_allocated < nr_pages) { + struct page *page; + int i; + + page = alloc_pages_node(nid, gfp, order); + if (unlikely(!page)) + break; + + /* + * Careful, we allocate and map page-order pages, but + * tracking is done per PAGE_SIZE page so as to keep the + * vm_struct APIs independent of the physical/mapped size. + */ + for (i = 0; i < (1U << order); i++) + pages[nr_allocated + i] = page + i; + + if (gfpflags_allow_blocking(gfp)) + cond_resched(); + + nr_allocated += 1U << order; + } + + return nr_allocated; +} + static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask, pgprot_t prot, unsigned int page_shift, int node) @@ -2790,37 +2838,11 @@ static void *__vmalloc_area_node(struct return NULL; } - area->nr_pages = 0; set_vm_area_page_order(area, page_shift - PAGE_SHIFT); page_order = vm_area_page_order(area); - if (!page_order) { - area->nr_pages = alloc_pages_bulk_array_node( - gfp_mask, node, nr_small_pages, area->pages); - } else { - /* - * Careful, we allocate and map page_order pages, but tracking is done - * per PAGE_SIZE page so as to keep the vm_struct APIs independent of - * the physical/mapped size. - */ - while (area->nr_pages < nr_small_pages) { - struct page *page; - int i; - - /* Compound pages required for remap_vmalloc_page */ - page = alloc_pages_node(node, gfp_mask | __GFP_COMP, page_order); - if (unlikely(!page)) - break; - - for (i = 0; i < (1U << page_order); i++) - area->pages[area->nr_pages + i] = page + i; - - if (gfpflags_allow_blocking(gfp_mask)) - cond_resched(); - - area->nr_pages += 1U << page_order; - } - } + area->nr_pages = vm_area_alloc_pages(gfp_mask, node, + page_order, nr_small_pages, area->pages); atomic_long_add(area->nr_pages, &nr_vmalloc_pages); @@ -2835,7 +2857,8 @@ static void *__vmalloc_area_node(struct goto fail; } - if (vmap_pages_range(addr, addr + size, prot, area->pages, page_shift) < 0) { + if (vmap_pages_range(addr, addr + size, prot, area->pages, + page_shift) < 0) { warn_alloc(gfp_mask, NULL, "vmalloc error: size %lu, failed to map pages", area->nr_pages * PAGE_SIZE); _
