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SubjectRe: [PATCH v6 4/6] mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
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On 7/12/21 1:09 AM, Feng Tang wrote:
> From: Ben Widawsky <ben.widawsky@intel.com>
>
> Implement the missing huge page allocation functionality while obeying
> the preferred node semantics. This is similar to the implementation
> for general page allocation, as it uses a fallback mechanism to try
> multiple preferred nodes first, and then all other nodes.
>
> [Thanks to 0day bot for caching the missing #ifdef CONFIG_NUMA issue]
>
> Link: https://lore.kernel.org/r/20200630212517.308045-12-ben.widawsky@intel.com
> Suggested-by: Michal Hocko <mhocko@suse.com>
> Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
> Co-developed-by: Feng Tang <feng.tang@intel.com>
> Signed-off-by: Feng Tang <feng.tang@intel.com>
> ---
> mm/hugetlb.c | 25 +++++++++++++++++++++++++
> mm/mempolicy.c | 3 ++-
> 2 files changed, 27 insertions(+), 1 deletion(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 924553aa8f78..3e84508c1b8c 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1164,7 +1164,18 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>
> gfp_mask = htlb_alloc_mask(h);
> nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
> +#ifdef CONFIG_NUMA
> + if (mpol->mode == MPOL_PREFERRED_MANY) {
> + page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
> + if (page)
> + goto check_reserve;
> + /* Fallback to all nodes */
> + nodemask = NULL;
> + }
> +#endif
> page = dequeue_huge_page_nodemask(h, gfp_mask, nid, nodemask);
> +
> +check_reserve:
> if (page && !avoid_reserve && vma_has_reserves(vma, chg)) {
> SetHPageRestoreReserve(page);
> h->resv_huge_pages--;
> @@ -2095,6 +2106,20 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
> nodemask_t *nodemask;
>
> nid = huge_node(vma, addr, gfp_mask, &mpol, &nodemask);
> +#ifdef CONFIG_NUMA
> + if (mpol->mode == MPOL_PREFERRED_MANY) {
> + gfp_t gfp = (gfp_mask | __GFP_NOWARN) & ~__GFP_DIRECT_RECLAIM;

I believe __GFP_NOWARN will be added later in alloc_buddy_huge_page, so
no need to add here?

> +
> + page = alloc_surplus_huge_page(h, gfp, nid, nodemask);
> + if (page) {
> + mpol_cond_put(mpol);
> + return page;
> + }
> +
> + /* Fallback to all nodes */
> + nodemask = NULL;
> + }
> +#endif
> page = alloc_surplus_huge_page(h, gfp_mask, nid, nodemask);
> mpol_cond_put(mpol);
>
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 9dce67fc9bb6..93f8789758a7 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -2054,7 +2054,8 @@ int huge_node(struct vm_area_struct *vma, unsigned long addr, gfp_t gfp_flags,
> huge_page_shift(hstate_vma(vma)));
> } else {
> nid = policy_node(gfp_flags, *mpol, numa_node_id());
> - if ((*mpol)->mode == MPOL_BIND)
> + if ((*mpol)->mode == MPOL_BIND ||
> + (*mpol)->mode == MPOL_PREFERRED_MANY)
> *nodemask = &(*mpol)->nodes;
> }
> return nid;
>

Other than the one nit above,

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>

--
Mike Kravetz

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