在 2021/10/14 5:46, Shakeel Butt 写道:

On Tue, Sep 28, 2021 at 5:03 AM Chen Wandun [off-list ref] wrote:

quoted

Eric Dumazet reported a strange numa spreading info in [1], and found
commit 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings") introduced
this issue [2].

Dig into the difference before and after this patch, page allocation has
some difference:

before:
alloc_large_system_hash
     __vmalloc
         __vmalloc_node(..., NUMA_NO_NODE, ...)
             __vmalloc_node_range
                 __vmalloc_area_node
                     alloc_page /* because NUMA_NO_NODE, so choose alloc_page branch */
                         alloc_pages_current
                             alloc_page_interleave /* can be proved by print policy mode */

after:
alloc_large_system_hash
     __vmalloc
         __vmalloc_node(..., NUMA_NO_NODE, ...)
             __vmalloc_node_range
                 __vmalloc_area_node
                     alloc_pages_node /* choose nid by nuam_mem_id() */
                         __alloc_pages_node(nid, ....)

So after commit 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings"),
it will allocate memory in current node instead of interleaving allocate
memory.

[1]
https://lore.kernel.org/linux-mm/CANn89iL6AAyWhfxdHO+jaT075iOa3XcYn9k6JJc7JR2XYn6k_Q@mail.gmail.com/ (local)

[2]
https://lore.kernel.org/linux-mm/CANn89iLofTR=AK-QOZY87RdUZENCZUT4O6a0hvhu3_EwRMerOg@mail.gmail.com/ (local)

Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
Reported-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Chen Wandun <redacted>
---
  mm/vmalloc.c | 33 ++++++++++++++++++++++++++-------
  1 file changed, 26 insertions(+), 7 deletions(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index f884706c5280..48e717626e94 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c

@@ -2823,6 +2823,8 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
                 unsigned int order, unsigned int nr_pages, struct page **pages)
  {
         unsigned int nr_allocated = 0;
+       struct page *page;
+       int i;

         /*
          * For order-0 pages we make use of bulk allocator, if

@@ -2833,6 +2835,7 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
         if (!order) {

Can you please replace the above with if (!order && nid != NUMA_NO_NODE)?

quoted

                 while (nr_allocated < nr_pages) {
                         unsigned int nr, nr_pages_request;
+                       page = NULL;

                         /*
                          * A maximum allowed request is hard-coded and is 100

@@ -2842,9 +2845,23 @@ vm_area_alloc_pages(gfp_t gfp, int nid,
                          */
                         nr_pages_request = min(100U, nr_pages - nr_allocated);

Undo the following change in this if block.

Yes, It seem like more simpler as you suggested, But it still have 
performance regression, I plan to change the following to consider
both mempolcy and alloc_pages_bulk.

Thanks,
Wandun

quoted

-                       nr = alloc_pages_bulk_array_node(gfp, nid,
-                               nr_pages_request, pages + nr_allocated);
-
+                       if (nid == NUMA_NO_NODE) {
+                               for (i = 0; i < nr_pages_request; i++) {
+                                       page = alloc_page(gfp);
+                                       if (page)
+                                               pages[nr_allocated + i] = page;
+                                       else {
+                                               nr = i;
+                                               break;
+                                       }
+                               }
+                               if (i >= nr_pages_request)
+                                       nr = nr_pages_request;
+                       } else {
+                               nr = alloc_pages_bulk_array_node(gfp, nid,
+                                                       nr_pages_request,
+                                                       pages + nr_allocated);
+                       }
                         nr_allocated += nr;
                         cond_resched();

@@ -2863,11 +2880,13 @@ vm_area_alloc_pages(gfp_t gfp, int nid,

Put the following line under "else if (order)"

quoted

                 gfp |= __GFP_COMP;

         /* High-order pages or fallback path if "bulk" fails. */
-       while (nr_allocated < nr_pages) {

Keep the following declarations inside the while loop.

quoted

-               struct page *page;
-               int i;

-               page = alloc_pages_node(nid, gfp, order);
+       page = NULL;
+       while (nr_allocated < nr_pages) {
+               if (nid == NUMA_NO_NODE)
+                       page = alloc_pages(gfp, order);
+               else
+                       page = alloc_pages_node(nid, gfp, order);
                 if (unlikely(!page))
                         break;

--
2.25.1

.