On Tue, Sep 28, 2021 at 5:03 AM Chen Wandun <chenwandun@xxxxxxxxxx> wrote:
>
> 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@xxxxxxxxxxxxxx/
>
> [2]
> https://lore.kernel.org/linux-mm/CANn89iLofTR=AK-QOZY87RdUZENCZUT4O6a0hvhu3_EwRMerOg@xxxxxxxxxxxxxx/
>
> Fixes: 121e6f3258fe ("mm/vmalloc: hugepage vmalloc mappings")
> Reported-by: Eric Dumazet <edumazet@xxxxxxxxxx>
> Signed-off-by: Chen Wandun <chenwandun@xxxxxxxxxx>
> ---
> 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)?
> 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.
> - 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)"
> 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.
> - 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
>
