在 2021/10/15 9:34, Nicholas Piggin 写道:

Excerpts from Chen Wandun's message of October 14, 2021 6:59 pm:

quoted

在 2021/10/14 5:46, Shakeel Butt 写道:

quoted

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 for finding and debugging this. These APIs are a maze of twisty
little passages, all alike so I could be as confused as I was when I
wrote that patch, but doesn't a minimal fix look something like this?

Yes, I sent a patch，it looks like as you show, besides it also
contains some performance optimization.

[PATCH] mm/vmalloc: introduce alloc_pages_bulk_array_mempolicy to 
accelerate memory allocation

Thanks,
Wandun