Re: [PATCH v2 3/6] mm, page_alloc: pass preferred nid instead of zonelist to allocator

Michal Hocko
2017-05-19T11:59:19Z

On Wed 17-05-17 10:11:37, Vlastimil Babka wrote:
> The main allocator function __alloc_pages_nodemask() takes a zonelist pointer
> as one of its parameters. All of its callers directly or indirectly obtain the
> zonelist via node_zonelist() using a preferred node id and gfp_mask. We can
> make the code a bit simpler by doing the zonelist lookup in
> __alloc_pages_nodemask(), passing it a preferred node id instead (gfp_mask is
> already another parameter).
>
> There are some code size benefits thanks to removal of inlined node_zonelist():
>
> bloat-o-meter add/remove: 2/2 grow/shrink: 4/36 up/down: 399/-1351 (-952)
>
> This will also make things simpler if we proceed with converting cpusets to
> zonelists.
>
> Signed-off-by: Vlastimil Babka <vbabka-AlSwsSmVLrQ@public.gmane.org>

Makes sense to me
Acked-by: Michal Hocko <mhocko-IBi9RG/b67k@public.gmane.org>

> ---
> include/linux/gfp.h | 11 +++++------
> include/linux/mempolicy.h | 6 +++---
> mm/hugetlb.c | 15 +++++++++------
> mm/memory_hotplug.c | 6 ++----
> mm/mempolicy.c | 41 +++++++++++++++++++----------------------
> mm/page_alloc.c | 10 +++++-----
> 6 files changed, 43 insertions(+), 46 deletions(-)
>
> diff --git a/include/linux/gfp.h b/include/linux/gfp.h
> index 2b1a44f5bdb6..666af3c39d00 100644
> --- a/include/linux/gfp.h
> +++ b/include/linux/gfp.h
> @@ -432,14 +432,13 @@ static inline void arch_alloc_page(struct page *page, int order) { }
> #endif
>
> struct page *
> -__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
> - struct zonelist *zonelist, nodemask_t *nodemask);
> +__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
> + nodemask_t *nodemask);
>
> static inline struct page *
> -__alloc_pages(gfp_t gfp_mask, unsigned int order,
> - struct zonelist *zonelist)
> +__alloc_pages(gfp_t gfp_mask, unsigned int order, int preferred_nid)
> {
> - return __alloc_pages_nodemask(gfp_mask, order, zonelist, NULL);
> + return __alloc_pages_nodemask(gfp_mask, order, preferred_nid, NULL);
> }
>
> /*
> @@ -452,7 +451,7 @@ __alloc_pages_node(int nid, gfp_t gfp_mask, unsigned int order)
> VM_BUG_ON(nid < 0 || nid >= MAX_NUMNODES);
> VM_WARN_ON(!node_online(nid));
>
> - return __alloc_pages(gfp_mask, order, node_zonelist(nid, gfp_mask));
> + return __alloc_pages(gfp_mask, order, nid);
> }
>
> /*
> diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
> index 5f4d8281832b..ecb6cbeede5a 100644
> --- a/include/linux/mempolicy.h
> +++ b/include/linux/mempolicy.h
> @@ -146,7 +146,7 @@ extern void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new,
> enum mpol_rebind_step step);
> extern void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new);
>
> -extern struct zonelist *huge_zonelist(struct vm_area_struct *vma,
> +extern int huge_node(struct vm_area_struct *vma,
> unsigned long addr, gfp_t gfp_flags,
> struct mempolicy **mpol, nodemask_t **nodemask);
> extern bool init_nodemask_of_mempolicy(nodemask_t *mask);
> @@ -269,13 +269,13 @@ static inline void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
> {
> }
>
> -static inline struct zonelist *huge_zonelist(struct vm_area_struct *vma,
> +static inline int huge_node(struct vm_area_struct *vma,
> unsigned long addr, gfp_t gfp_flags,
> struct mempolicy **mpol, nodemask_t **nodemask)
> {
> *mpol = NULL;
> *nodemask = NULL;
> - return node_zonelist(0, gfp_flags);
> + return 0;
> }
>
> static inline bool init_nodemask_of_mempolicy(nodemask_t *m)
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index e5828875f7bb..9f1f399bb913 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -904,6 +904,8 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
> struct page *page = NULL;
> struct mempolicy *mpol;
> nodemask_t *nodemask;
> + gfp_t gfp_mask;
> + int nid;
> struct zonelist *zonelist;
> struct zone *zone;
> struct zoneref *z;
> @@ -924,12 +926,13 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>
> retry_cpuset:
> cpuset_mems_cookie = read_mems_allowed_begin();
> - zonelist = huge_zonelist(vma, address,
> - htlb_alloc_mask(h), &mpol, &nodemask);
> + gfp_mask = htlb_alloc_mask(h);
> + nid = huge_node(vma, address, gfp_mask, &mpol, &nodemask);
> + zonelist = node_zonelist(nid, gfp_mask);
>
> for_each_zone_zonelist_nodemask(zone, z, zonelist,
> MAX_NR_ZONES - 1, nodemask) {
> - if (cpuset_zone_allowed(zone, htlb_alloc_mask(h))) {
> + if (cpuset_zone_allowed(zone, gfp_mask)) {
> page = dequeue_huge_page_node(h, zone_to_nid(zone));
> if (page) {
> if (avoid_reserve)
> @@ -1545,13 +1548,13 @@ static struct page *__hugetlb_alloc_buddy_huge_page(struct hstate *h,
> do {
> struct page *page;
> struct mempolicy *mpol;
> - struct zonelist *zl;
> + int nid;
> nodemask_t *nodemask;
>
> cpuset_mems_cookie = read_mems_allowed_begin();
> - zl = huge_zonelist(vma, addr, gfp, &mpol, &nodemask);
> + nid = huge_node(vma, addr, gfp, &mpol, &nodemask);
> mpol_cond_put(mpol);
> - page = __alloc_pages_nodemask(gfp, order, zl, nodemask);
> + page = __alloc_pages_nodemask(gfp, order, nid, nodemask);
> if (page)
> return page;
> } while (read_mems_allowed_retry(cpuset_mems_cookie));
> diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
> index 717c5e301aa8..ba9e09817f37 100644
> --- a/mm/memory_hotplug.c
> +++ b/mm/memory_hotplug.c
> @@ -1596,11 +1596,9 @@ static struct page *new_node_page(struct page *page, unsigned long private,
> gfp_mask |= __GFP_HIGHMEM;
>
> if (!nodes_empty(nmask))
> - new_page = __alloc_pages_nodemask(gfp_mask, 0,
> - node_zonelist(nid, gfp_mask), &nmask);
> + new_page = __alloc_pages_nodemask(gfp_mask, 0, nid, &nmask);
> if (!new_page)
> - new_page = __alloc_pages(gfp_mask, 0,
> - node_zonelist(nid, gfp_mask));
> + new_page = __alloc_pages(gfp_mask, 0, nid);
>
> return new_page;
> }
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index d77177c7283b..c60807625fd5 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1669,9 +1669,9 @@ static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
> return NULL;
> }
>
> -/* Return a zonelist indicated by gfp for node representing a mempolicy */
> -static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
> - int nd)
> +/* Return the node id preferred by the given mempolicy, or the given id */
> +static int policy_node(gfp_t gfp, struct mempolicy *policy,
> + int nd)
> {
> if (policy->mode == MPOL_PREFERRED && !(policy->flags & MPOL_F_LOCAL))
> nd = policy->v.preferred_node;
> @@ -1684,7 +1684,7 @@ static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy,
> WARN_ON_ONCE(policy->mode == MPOL_BIND && (gfp & __GFP_THISNODE));
> }
>
> - return node_zonelist(nd, gfp);
> + return nd;
> }
>
> /* Do dynamic interleaving for a process */
> @@ -1791,38 +1791,37 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
>
> #ifdef CONFIG_HUGETLBFS
> /*
> - * huge_zonelist(@vma, @addr, @gfp_flags, @mpol)
> + * huge_node(@vma, @addr, @gfp_flags, @mpol)
> * @vma: virtual memory area whose policy is sought
> * @addr: address in @vma for shared policy lookup and interleave policy
> * @gfp_flags: for requested zone
> * @mpol: pointer to mempolicy pointer for reference counted mempolicy
> * @nodemask: pointer to nodemask pointer for MPOL_BIND nodemask
> *
> - * Returns a zonelist suitable for a huge page allocation and a pointer
> + * Returns a nid suitable for a huge page allocation and a pointer
> * to the struct mempolicy for conditional unref after allocation.
> * If the effective policy is 'BIND, returns a pointer to the mempolicy's
> * @nodemask for filtering the zonelist.
> *
> * Must be protected by read_mems_allowed_begin()
> */
> -struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
> - gfp_t gfp_flags, struct mempolicy **mpol,
> - nodemask_t **nodemask)
> +int huge_node(struct vm_area_struct *vma, unsigned long addr, gfp_t gfp_flags,
> + struct mempolicy **mpol, nodemask_t **nodemask)
> {
> - struct zonelist *zl;
> + int nid;
>
> *mpol = get_vma_policy(vma, addr);
> *nodemask = NULL; /* assume !MPOL_BIND */
>
> if (unlikely((*mpol)->mode == MPOL_INTERLEAVE)) {
> - zl = node_zonelist(interleave_nid(*mpol, vma, addr,
> - huge_page_shift(hstate_vma(vma))), gfp_flags);
> + nid = interleave_nid(*mpol, vma, addr,
> + huge_page_shift(hstate_vma(vma)));
> } else {
> - zl = policy_zonelist(gfp_flags, *mpol, numa_node_id());
> + nid = policy_node(gfp_flags, *mpol, numa_node_id());
> if ((*mpol)->mode == MPOL_BIND)
> *nodemask = &(*mpol)->v.nodes;
> }
> - return zl;
> + return nid;
> }
>
> /*
> @@ -1924,12 +1923,10 @@ bool mempolicy_nodemask_intersects(struct task_struct *tsk,
> static struct page *alloc_page_interleave(gfp_t gfp, unsigned order,
> unsigned nid)
> {
> - struct zonelist *zl;
> struct page *page;
>
> - zl = node_zonelist(nid, gfp);
> - page = __alloc_pages(gfp, order, zl);
> - if (page && page_zone(page) == zonelist_zone(&zl->_zonerefs[0]))
> + page = __alloc_pages(gfp, order, nid);
> + if (page && page_to_nid(page) == nid)
> inc_zone_page_state(page, NUMA_INTERLEAVE_HIT);
> return page;
> }
> @@ -1963,8 +1960,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
> {
> struct mempolicy *pol;
> struct page *page;
> + int preferred_nid;
> unsigned int cpuset_mems_cookie;
> - struct zonelist *zl;
> nodemask_t *nmask;
>
> retry_cpuset:
> @@ -2007,8 +2004,8 @@ alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
> }
>
> nmask = policy_nodemask(gfp, pol);
> - zl = policy_zonelist(gfp, pol, node);
> - page = __alloc_pages_nodemask(gfp, order, zl, nmask);
> + preferred_nid = policy_node(gfp, pol, node);
> + page = __alloc_pages_nodemask(gfp, order, preferred_nid, nmask);
> mpol_cond_put(pol);
> out:
> if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
> @@ -2055,7 +2052,7 @@ struct page *alloc_pages_current(gfp_t gfp, unsigned order)
> page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
> else
> page = __alloc_pages_nodemask(gfp, order,
> - policy_zonelist(gfp, pol, numa_node_id()),
> + policy_node(gfp, pol, numa_node_id()),
> policy_nodemask(gfp, pol));
>
> if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie)))
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 43aa767c3188..0aceca1076dc 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -3962,12 +3962,12 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order,
> }
>
> static inline bool prepare_alloc_pages(gfp_t gfp_mask, unsigned int order,
> - struct zonelist *zonelist, nodemask_t *nodemask,
> + int preferred_nid, nodemask_t *nodemask,
> struct alloc_context *ac, gfp_t *alloc_mask,
> unsigned int *alloc_flags)
> {
> ac->high_zoneidx = gfp_zone(gfp_mask);
> - ac->zonelist = zonelist;
> + ac->zonelist = node_zonelist(preferred_nid, gfp_mask);
> ac->nodemask = nodemask;
> ac->migratetype = gfpflags_to_migratetype(gfp_mask);
>
> @@ -4012,8 +4012,8 @@ static inline void finalise_ac(gfp_t gfp_mask,
> * This is the 'heart' of the zoned buddy allocator.
> */
> struct page *
> -__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
> - struct zonelist *zonelist, nodemask_t *nodemask)
> +__alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order, int preferred_nid,
> + nodemask_t *nodemask)
> {
> struct page *page;
> unsigned int alloc_flags = ALLOC_WMARK_LOW;
> @@ -4021,7 +4021,7 @@ __alloc_pages_nodemask(gfp_t gfp_mask, unsigned int order,
> struct alloc_context ac = { };
>
> gfp_mask &= gfp_allowed_mask;
> - if (!prepare_alloc_pages(gfp_mask, order, zonelist, nodemask, &ac, &alloc_mask, &alloc_flags))
> + if (!prepare_alloc_pages(gfp_mask, order, preferred_nid, nodemask, &ac, &alloc_mask, &alloc_flags))
> return NULL;
>
> finalise_ac(gfp_mask, order, &ac);
> --
> 2.12.2

--
Michal Hocko
SUSE Labs