[PATCH -mm] mm/mempolicy: use unified 'nodes' for bind/interleave/prefer policies

From: Feng Tang
Date: Fri Jun 11 2021 - 04:23:54 EST

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From: Ben Widawsky <ben.widawsky@xxxxxxxxx>

Current structure 'mempolicy' uses a union to store the node info
for bind/interleave/perfer policies.

union {
short preferred_node; /* preferred */
nodemask_t nodes; /* interleave/bind */
/* undefined for default */
} v;

Since preferred node can also be represented by a nodemask_t with
only ont bit set, unify these policies with using one nodemask_t
'nodes', which can remove a union, simplify the code and make
it easier to support future's new policy's node info.

Link: https://lore.kernel.org/r/20200630212517.308045-7-ben.widawsky@xxxxxxxxx
Co-developed-by: Feng Tang <feng.tang@xxxxxxxxx>
Signed-off-by: Ben Widawsky <ben.widawsky@xxxxxxxxx>
Signed-off-by: Feng Tang <feng.tang@xxxxxxxxx>
---
include/linux/mempolicy.h | 7 +---
mm/mempolicy.c | 96 ++++++++++++++++++++++-------------------------
2 files changed, 46 insertions(+), 57 deletions(-)

diff --git a/include/linux/mempolicy.h b/include/linux/mempolicy.h
index 8773c55..0aaf91b 100644
--- a/include/linux/mempolicy.h
+++ b/include/linux/mempolicy.h
@@ -46,11 +46,8 @@ struct mempolicy {
atomic_t refcnt;
unsigned short mode; /* See MPOL_* above */
unsigned short flags; /* See set_mempolicy() MPOL_F_* above */
- union {
- short preferred_node; /* preferred */
- nodemask_t nodes; /* interleave/bind */
- /* undefined for default */
- } v;
+ nodemask_t nodes; /* interleave/bind/perfer */
+
union {
nodemask_t cpuset_mems_allowed; /* relative to these nodes */
nodemask_t user_nodemask; /* nodemask passed by user */
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 8739bfd..e32360e 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -193,7 +193,7 @@ static int mpol_new_interleave(struct mempolicy *pol, const nodemask_t *nodes)
{
if (nodes_empty(*nodes))
return -EINVAL;
- pol->v.nodes = *nodes;
+ pol->nodes = *nodes;
return 0;
}

@@ -201,7 +201,9 @@ static int mpol_new_preferred(struct mempolicy *pol, const nodemask_t *nodes)
{
if (nodes_empty(*nodes))
return -EINVAL;
- pol->v.preferred_node = first_node(*nodes);
+
+ nodes_clear(pol->nodes);
+ node_set(first_node(*nodes), pol->nodes);
return 0;
}

@@ -209,7 +211,7 @@ static int mpol_new_bind(struct mempolicy *pol, const nodemask_t *nodes)
{
if (nodes_empty(*nodes))
return -EINVAL;
- pol->v.nodes = *nodes;
+ pol->nodes = *nodes;
return 0;
}

@@ -324,7 +326,7 @@ static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes)
else if (pol->flags & MPOL_F_RELATIVE_NODES)
mpol_relative_nodemask(&tmp, &pol->w.user_nodemask, nodes);
else {
- nodes_remap(tmp, pol->v.nodes, pol->w.cpuset_mems_allowed,
+ nodes_remap(tmp, pol->nodes, pol->w.cpuset_mems_allowed,
*nodes);
pol->w.cpuset_mems_allowed = *nodes;
}
@@ -332,7 +334,7 @@ static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes)
if (nodes_empty(tmp))
tmp = *nodes;

- pol->v.nodes = tmp;
+ pol->nodes = tmp;
}

static void mpol_rebind_preferred(struct mempolicy *pol,
@@ -897,15 +899,12 @@ static void get_policy_nodemask(struct mempolicy *p, nodemask_t *nodes)
switch (p->mode) {
case MPOL_BIND:
case MPOL_INTERLEAVE:
- *nodes = p->v.nodes;
+ case MPOL_PREFERRED:
+ *nodes = p->nodes;
break;
case MPOL_LOCAL:
/* return empty node mask for local allocation */
break;
-
- case MPOL_PREFERRED:
- node_set(p->v.preferred_node, *nodes);
- break;
default:
BUG();
}
@@ -989,7 +988,7 @@ static long do_get_mempolicy(int *policy, nodemask_t *nmask,
*policy = err;
} else if (pol == current->mempolicy &&
pol->mode == MPOL_INTERLEAVE) {
- *policy = next_node_in(current->il_prev, pol->v.nodes);
+ *policy = next_node_in(current->il_prev, pol->nodes);
} else {
err = -EINVAL;
goto out;
@@ -1857,14 +1856,14 @@ static int apply_policy_zone(struct mempolicy *policy, enum zone_type zone)
BUG_ON(dynamic_policy_zone == ZONE_MOVABLE);

/*
- * if policy->v.nodes has movable memory only,
+ * if policy->nodes has movable memory only,
* we apply policy when gfp_zone(gfp) = ZONE_MOVABLE only.
*
- * policy->v.nodes is intersect with node_states[N_MEMORY].
+ * policy->nodes is intersect with node_states[N_MEMORY].
* so if the following test fails, it implies
- * policy->v.nodes has movable memory only.
+ * policy->nodes has movable memory only.
*/
- if (!nodes_intersects(policy->v.nodes, node_states[N_HIGH_MEMORY]))
+ if (!nodes_intersects(policy->nodes, node_states[N_HIGH_MEMORY]))
dynamic_policy_zone = ZONE_MOVABLE;

return zone >= dynamic_policy_zone;
@@ -1879,8 +1878,8 @@ 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) &&
apply_policy_zone(policy, gfp_zone(gfp)) &&
- cpuset_nodemask_valid_mems_allowed(&policy->v.nodes))
- return &policy->v.nodes;
+ cpuset_nodemask_valid_mems_allowed(&policy->nodes))
+ return &policy->nodes;

return NULL;
}
@@ -1889,7 +1888,7 @@ nodemask_t *policy_nodemask(gfp_t gfp, struct mempolicy *policy)
static int policy_node(gfp_t gfp, struct mempolicy *policy, int nd)
{
if (policy->mode == MPOL_PREFERRED) {
- nd = policy->v.preferred_node;
+ nd = first_node(policy->nodes);
} else {
/*
* __GFP_THISNODE shouldn't even be used with the bind policy
@@ -1908,7 +1907,7 @@ static unsigned interleave_nodes(struct mempolicy *policy)
unsigned next;
struct task_struct *me = current;

- next = next_node_in(me->il_prev, policy->v.nodes);
+ next = next_node_in(me->il_prev, policy->nodes);
if (next < MAX_NUMNODES)
me->il_prev = next;
return next;
@@ -1932,7 +1931,7 @@ unsigned int mempolicy_slab_node(void)

switch (policy->mode) {
case MPOL_PREFERRED:
- return policy->v.preferred_node;
+ return first_node(policy->nodes);

case MPOL_INTERLEAVE:
return interleave_nodes(policy);
@@ -1948,7 +1947,7 @@ unsigned int mempolicy_slab_node(void)
enum zone_type highest_zoneidx = gfp_zone(GFP_KERNEL);
zonelist = &NODE_DATA(node)->node_zonelists[ZONELIST_FALLBACK];
z = first_zones_zonelist(zonelist, highest_zoneidx,
- &policy->v.nodes);
+ &policy->nodes);
return z->zone ? zone_to_nid(z->zone) : node;
}
case MPOL_LOCAL:
@@ -1961,12 +1960,12 @@ unsigned int mempolicy_slab_node(void)

/*
* Do static interleaving for a VMA with known offset @n. Returns the n'th
- * node in pol->v.nodes (starting from n=0), wrapping around if n exceeds the
+ * node in pol->nodes (starting from n=0), wrapping around if n exceeds the
* number of present nodes.
*/
static unsigned offset_il_node(struct mempolicy *pol, unsigned long n)
{
- unsigned nnodes = nodes_weight(pol->v.nodes);
+ unsigned nnodes = nodes_weight(pol->nodes);
unsigned target;
int i;
int nid;
@@ -1974,9 +1973,9 @@ static unsigned offset_il_node(struct mempolicy *pol, unsigned long n)
if (!nnodes)
return numa_node_id();
target = (unsigned int)n % nnodes;
- nid = first_node(pol->v.nodes);
+ nid = first_node(pol->nodes);
for (i = 0; i < target; i++)
- nid = next_node(nid, pol->v.nodes);
+ nid = next_node(nid, pol->nodes);
return nid;
}

@@ -2032,7 +2031,7 @@ int huge_node(struct vm_area_struct *vma, unsigned long addr, gfp_t gfp_flags,
} else {
nid = policy_node(gfp_flags, *mpol, numa_node_id());
if ((*mpol)->mode == MPOL_BIND)
- *nodemask = &(*mpol)->v.nodes;
+ *nodemask = &(*mpol)->nodes;
}
return nid;
}
@@ -2056,7 +2055,6 @@ int huge_node(struct vm_area_struct *vma, unsigned long addr, gfp_t gfp_flags,
bool init_nodemask_of_mempolicy(nodemask_t *mask)
{
struct mempolicy *mempolicy;
- int nid;

if (!(mask && current->mempolicy))
return false;
@@ -2065,18 +2063,13 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask)
mempolicy = current->mempolicy;
switch (mempolicy->mode) {
case MPOL_PREFERRED:
- nid = mempolicy->v.preferred_node;
- init_nodemask_of_node(mask, nid);
- break;
-
case MPOL_BIND:
case MPOL_INTERLEAVE:
- *mask = mempolicy->v.nodes;
+ *mask = mempolicy->nodes;
break;

case MPOL_LOCAL:
- nid = numa_node_id();
- init_nodemask_of_node(mask, nid);
+ init_nodemask_of_node(mask, numa_node_id());
break;

default:
@@ -2110,7 +2103,7 @@ bool mempolicy_in_oom_domain(struct task_struct *tsk,
task_lock(tsk);
mempolicy = tsk->mempolicy;
if (mempolicy && mempolicy->mode == MPOL_BIND)
- ret = nodes_intersects(mempolicy->v.nodes, *mask);
+ ret = nodes_intersects(mempolicy->nodes, *mask);
task_unlock(tsk);

return ret;
@@ -2184,7 +2177,7 @@ struct page *alloc_pages_vma(gfp_t gfp, int order, struct vm_area_struct *vma,
* node in its nodemask, we allocate the standard way.
*/
if (pol->mode == MPOL_PREFERRED)
- hpage_node = pol->v.preferred_node;
+ hpage_node = first_node(pol->nodes);

nmask = policy_nodemask(gfp, pol);
if (!nmask || node_isset(hpage_node, *nmask)) {
@@ -2317,9 +2310,8 @@ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b)
switch (a->mode) {
case MPOL_BIND:
case MPOL_INTERLEAVE:
- return !!nodes_equal(a->v.nodes, b->v.nodes);
case MPOL_PREFERRED:
- return a->v.preferred_node == b->v.preferred_node;
+ return !!nodes_equal(a->nodes, b->nodes);
case MPOL_LOCAL:
return true;
default:
@@ -2459,7 +2451,7 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
break;

case MPOL_PREFERRED:
- polnid = pol->v.preferred_node;
+ polnid = first_node(pol->nodes);
break;

case MPOL_LOCAL:
@@ -2469,7 +2461,7 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
case MPOL_BIND:
/* Optimize placement among multiple nodes via NUMA balancing */
if (pol->flags & MPOL_F_MORON) {
- if (node_isset(thisnid, pol->v.nodes))
+ if (node_isset(thisnid, pol->nodes))
break;
goto out;
}
@@ -2480,12 +2472,12 @@ int mpol_misplaced(struct page *page, struct vm_area_struct *vma, unsigned long
* else select nearest allowed node, if any.
* If no allowed nodes, use current [!misplaced].
*/
- if (node_isset(curnid, pol->v.nodes))
+ if (node_isset(curnid, pol->nodes))
goto out;
z = first_zones_zonelist(
node_zonelist(numa_node_id(), GFP_HIGHUSER),
gfp_zone(GFP_HIGHUSER),
- &pol->v.nodes);
+ &pol->nodes);
polnid = zone_to_nid(z->zone);
break;

@@ -2688,7 +2680,7 @@ int mpol_set_shared_policy(struct shared_policy *info,
vma->vm_pgoff,
sz, npol ? npol->mode : -1,
npol ? npol->flags : -1,
- npol ? nodes_addr(npol->v.nodes)[0] : NUMA_NO_NODE);
+ npol ? nodes_addr(npol->nodes)[0] : NUMA_NO_NODE);

if (npol) {
new = sp_alloc(vma->vm_pgoff, vma->vm_pgoff + sz, npol);
@@ -2786,7 +2778,7 @@ void __init numa_policy_init(void)
.refcnt = ATOMIC_INIT(1),
.mode = MPOL_PREFERRED,
.flags = MPOL_F_MOF | MPOL_F_MORON,
- .v = { .preferred_node = nid, },
+ .nodes = nodemask_of_node(nid),
};
}

@@ -2945,12 +2937,14 @@ int mpol_parse_str(char *str, struct mempolicy **mpol)
* Save nodes for mpol_to_str() to show the tmpfs mount options
* for /proc/mounts, /proc/pid/mounts and /proc/pid/mountinfo.
*/
- if (mode != MPOL_PREFERRED)
- new->v.nodes = nodes;
- else if (nodelist)
- new->v.preferred_node = first_node(nodes);
- else
+ if (mode != MPOL_PREFERRED) {
+ new->nodes = nodes;
+ } else if (nodelist) {
+ nodes_clear(new->nodes);
+ node_set(first_node(nodes), new->nodes);
+ } else {
new->mode = MPOL_LOCAL;
+ }

/*
* Save nodes for contextualization: this will be used to "clone"
@@ -2999,11 +2993,9 @@ void mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol)
case MPOL_LOCAL:
break;
case MPOL_PREFERRED:
- node_set(pol->v.preferred_node, nodes);
- break;
case MPOL_BIND:
case MPOL_INTERLEAVE:
- nodes = pol->v.nodes;
+ nodes = pol->nodes;
break;
default:
WARN_ON_ONCE(1);
--
2.7.4

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