[PATCH 02/10] mm: mempolicy: introduce MPOL_HYBRID policy

Yang Shi
2019-03-23T04:45:18Z

Introduce a new NUMA policy, MPOL_HYBRID. It behaves like MPOL_BIND,
but since we need migrate pages from non-DRAM node (i.e. PMEM node) to
DRAM node on demand, MPOL_HYBRID would do page migration on numa fault,
so it would have MPOL_F_MOF set by default.

The NUMA balancing stuff will be enabled in the following patch.

Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
---
include/uapi/linux/mempolicy.h | 1 +
mm/mempolicy.c | 56 +++++++++++++++++++++++++++++++++++++-----
2 files changed, 51 insertions(+), 6 deletions(-)

diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h
index 3354774..0fdc73d 100644
--- a/include/uapi/linux/mempolicy.h
+++ b/include/uapi/linux/mempolicy.h
@@ -22,6 +22,7 @@ enum {
MPOL_BIND,
MPOL_INTERLEAVE,
MPOL_LOCAL,
+ MPOL_HYBRID,
MPOL_MAX, /* always last member of enum */
};

diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index af171cc..7d0a432 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -31,6 +31,10 @@
* but useful to set in a VMA when you have a non default
* process policy.
*
+ * hybrid Only allocate memory on specific set of nodes. If the set of
+ * nodes include non-DRAM nodes, NUMA balancing would promote
+ * the page to DRAM node.
+ *
* default Allocate on the local node first, or when on a VMA
* use the process policy. This is what Linux always did
* in a NUMA aware kernel and still does by, ahem, default.
@@ -191,6 +195,17 @@ static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
return 0;
}

+static int mpol_new_hybrid(struct mempolicy *pol, const nodemask_t *nodes)
+{
+ if (nodes_empty(*nodes))
+ return -EINVAL;
+
+ /* Hybrid policy would promote pages in page fault */
+ pol->flags |= MPOL_F_MOF;
+ pol->v.nodes = *nodes;
+ return 0;
+}
+
/*
* mpol_set_nodemask is called after mpol_new() to set up the nodemask, if
* any, for the new policy. mpol_new() has already validated the nodes
@@ -401,6 +416,10 @@ void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
.create = mpol_new_bind,
.rebind = mpol_rebind_nodemask,
},
+ [MPOL_HYBRID] = {
+ .create = mpol_new_hybrid,
+ .rebind = mpol_rebind_nodemask,
+ },
};

static void migrate_page_add(struct page *page, struct list_head *pagelist,
@@ -782,6 +801,8 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
return;

switch (p->mode) {
+ case MPOL_HYBRID:
+ /* Fall through */
case MPOL_BIND:
/* Fall through */
case MPOL_INTERLEAVE:
@@ -1721,8 +1742,12 @@ static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
*/
static nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
{
- /* Lower zones don't get a nodemask applied for MPOL_BIND */
- if (unlikely(policy->mode == MPOL_BIND) &&
+ /*
+ * Lower zones don't get a nodemask applied for MPOL_BIND
+ * or MPOL_HYBRID.
+ */
+ if (unlikely((policy->mode == MPOL_BIND) ||
+ (policy->mode == MPOL_HYBRID)) &&
apply_policy_zone(policy, gfp_zone(gfp)) &&
cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
return &policy->v.nodes;
@@ -1742,7 +1767,9 @@ static int policy_node(gfp_t gfp, struct mempolicy *policy,
* because we might easily break the expectation to stay on the
* requested node and not break the policy.
*/
- WARN_ON_ONCE(policy->mode == MPOL_BIND && (gfp & __GFP_THISNODE));
+ WARN_ON_ONCE((policy->mode == MPOL_BIND ||
+ policy->mode == MPOL_HYBRID) &&
+ (gfp & __GFP_THISNODE));
}

return nd;
@@ -1786,6 +1813,8 @@ unsigned int mempolicy_slab_node(void)
case MPOL_INTERLEAVE:
return interleave_nodes(policy);

+ case MPOL_HYBRID:
+ /* Fall through */
case MPOL_BIND: {
struct zoneref *z;

@@ -1856,7 +1885,8 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
* @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
+ * @nodemask: pointer to nodemask pointer for MPOL_BIND or MPOL_HYBRID
+ * nodemask
*
* Returns a nid suitable for a huge page allocation and a pointer
* to the struct mempolicy for conditional unref after allocation.
@@ -1871,14 +1901,16 @@ int huge_node(struct vm_area_struct *vma, unsigned long addr, gfp_t gfp_flags,
int nid;

*mpol = get_vma_policy(vma, addr);
- *nodemask = NULL; /* assume !MPOL_BIND */
+ /* assume !MPOL_BIND || !MPOL_HYBRID */
+ *nodemask = NULL;

if (unlikely((*mpol)->mode == MPOL_INTERLEAVE)) {
nid = interleave_nid(*mpol, vma, addr,
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_HYBRID)
*nodemask = &(*mpol)->v.nodes;
}
return nid;
@@ -1919,6 +1951,8 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask)
init_nodemask_of_node(mask, nid);
break;

+ case MPOL_HYBRID:
+ /* Fall through */
case MPOL_BIND:
/* Fall through */
case MPOL_INTERLEAVE:
@@ -1966,6 +2000,7 @@ bool mempolicy_nodemask_intersects(struct task_struct *tsk,
* nodes in mask.
*/
break;
+ case MPOL_HYBRID:
case MPOL_BIND:
case MPOL_INTERLEAVE:
ret = nodes_intersects(mempolicy->v.nodes, *mask);
@@ -2170,6 +2205,8 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
return false;

switch (a->mode) {
+ case MPOL_HYBRID:
+ /* Fall through */
case MPOL_BIND:
/* Fall through */
case MPOL_INTERLEAVE:
@@ -2325,6 +2362,9 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
polnid = pol->v.preferred_node;
break;

+ case MPOL_HYBRID:
+ /* Fall through */
+
case MPOL_BIND:

/*
@@ -2693,6 +2733,7 @@ void numa_default_policy(void)
[MPOL_BIND] = "bind",
[MPOL_INTERLEAVE] = "interleave",
[MPOL_LOCAL] = "local",
+ [MPOL_HYBRID] = "hybrid",
};

@@ -2768,6 +2809,8 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
if (!nodelist)
err = 0;
goto out;
+ case MPOL_HYBRID:
+ /* Fall through */
case MPOL_BIND:
/*
* Insist on a nodelist
@@ -2856,6 +2899,7 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
else
node_set(pol->v.preferred_node, nodes);
break;
+ case MPOL_HYBRID:
case MPOL_BIND:
case MPOL_INTERLEAVE:
nodes = pol->v.nodes;
--
1.8.3.1