The patch titled
Subject: mm/vmalloc: Fallback to a single page allocator
has been added to the -mm tree. Its filename is
mm-vmalloc-fallback-to-a-single-page-allocator.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-vmalloc-fallback-to-a-single-page-allocator.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-vmalloc-fallback-to-a-single-page-allocator.patch
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------------------------------------------------------
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>
Cc: Mel Gorman <mgorman@xxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
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
@@ -2755,6 +2755,54 @@ 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)
@@ -2787,37 +2835,11 @@ 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);
@@ -2832,7 +2854,8 @@ 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);
_
Patches currently in -mm which might be from urezki@xxxxxxxxx are
mm-page_alloc-add-an-alloc_pages_bulk_array_node-helper.patch
mm-vmalloc-switch-to-bulk-allocator-in-__vmalloc_area_node.patch
mm-vmalloc-print-a-warning-message-first-on-failure.patch
mm-vmalloc-remove-quoted-string-split-across-lines.patch
mm-vmalloc-fallback-to-a-single-page-allocator.patch
