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-rw-r--r--mm/mempolicy.c227
1 files changed, 159 insertions, 68 deletions
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 08f40a2..5d6fb33 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -119,7 +119,22 @@ struct mempolicy default_policy = {
static const struct mempolicy_operations {
int (*create)(struct mempolicy *pol, const nodemask_t *nodes);
- void (*rebind)(struct mempolicy *pol, const nodemask_t *nodes);
+ /*
+ * If read-side task has no lock to protect task->mempolicy, write-side
+ * task will rebind the task->mempolicy by two step. The first step is
+ * setting all the newly nodes, and the second step is cleaning all the
+ * disallowed nodes. In this way, we can avoid finding no node to alloc
+ * page.
+ * If we have a lock to protect task->mempolicy in read-side, we do
+ * rebind directly.
+ *
+ * step:
+ * MPOL_REBIND_ONCE - do rebind work at once
+ * MPOL_REBIND_STEP1 - set all the newly nodes
+ * MPOL_REBIND_STEP2 - clean all the disallowed nodes
+ */
+ void (*rebind)(struct mempolicy *pol, const nodemask_t *nodes,
+ enum mpol_rebind_step step);
} mpol_ops[MPOL_MAX];
/* Check that the nodemask contains at least one populated zone */
@@ -127,9 +142,6 @@ static int is_valid_nodemask(const nodemask_t *nodemask)
{
int nd, k;
- /* Check that there is something useful in this mask */
- k = policy_zone;
-
for_each_node_mask(nd, *nodemask) {
struct zone *z;
@@ -145,7 +157,7 @@ static int is_valid_nodemask(const nodemask_t *nodemask)
static inline int mpol_store_user_nodemask(const struct mempolicy *pol)
{
- return pol->flags & (MPOL_F_STATIC_NODES | MPOL_F_RELATIVE_NODES);
+ return pol->flags & MPOL_MODE_FLAGS;
}
static void mpol_relative_nodemask(nodemask_t *ret, const nodemask_t *orig,
@@ -277,12 +289,19 @@ void __mpol_put(struct mempolicy *p)
kmem_cache_free(policy_cache, p);
}
-static void mpol_rebind_default(struct mempolicy *pol, const nodemask_t *nodes)
+static void mpol_rebind_default(struct mempolicy *pol, const nodemask_t *nodes,
+ enum mpol_rebind_step step)
{
}
-static void mpol_rebind_nodemask(struct mempolicy *pol,
- const nodemask_t *nodes)
+/*
+ * step:
+ * MPOL_REBIND_ONCE - do rebind work at once
+ * MPOL_REBIND_STEP1 - set all the newly nodes
+ * MPOL_REBIND_STEP2 - clean all the disallowed nodes
+ */
+static void mpol_rebind_nodemask(struct mempolicy *pol, const nodemask_t *nodes,
+ enum mpol_rebind_step step)
{
nodemask_t tmp;
@@ -291,12 +310,31 @@ static void mpol_rebind_nodemask(struct mempolicy *pol,
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);
- pol->w.cpuset_mems_allowed = *nodes;
+ /*
+ * if step == 1, we use ->w.cpuset_mems_allowed to cache the
+ * result
+ */
+ if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP1) {
+ nodes_remap(tmp, pol->v.nodes,
+ pol->w.cpuset_mems_allowed, *nodes);
+ pol->w.cpuset_mems_allowed = step ? tmp : *nodes;
+ } else if (step == MPOL_REBIND_STEP2) {
+ tmp = pol->w.cpuset_mems_allowed;
+ pol->w.cpuset_mems_allowed = *nodes;
+ } else
+ BUG();
}
- pol->v.nodes = tmp;
+ if (nodes_empty(tmp))
+ tmp = *nodes;
+
+ if (step == MPOL_REBIND_STEP1)
+ nodes_or(pol->v.nodes, pol->v.nodes, tmp);
+ else if (step == MPOL_REBIND_ONCE || step == MPOL_REBIND_STEP2)
+ pol->v.nodes = tmp;
+ else
+ BUG();
+
if (!node_isset(current->il_next, tmp)) {
current->il_next = next_node(current->il_next, tmp);
if (current->il_next >= MAX_NUMNODES)
@@ -307,7 +345,8 @@ static void mpol_rebind_nodemask(struct mempolicy *pol,
}
static void mpol_rebind_preferred(struct mempolicy *pol,
- const nodemask_t *nodes)
+ const nodemask_t *nodes,
+ enum mpol_rebind_step step)
{
nodemask_t tmp;
@@ -330,16 +369,45 @@ static void mpol_rebind_preferred(struct mempolicy *pol,
}
}
-/* Migrate a policy to a different set of nodes */
-static void mpol_rebind_policy(struct mempolicy *pol,
- const nodemask_t *newmask)
+/*
+ * mpol_rebind_policy - Migrate a policy to a different set of nodes
+ *
+ * If read-side task has no lock to protect task->mempolicy, write-side
+ * task will rebind the task->mempolicy by two step. The first step is
+ * setting all the newly nodes, and the second step is cleaning all the
+ * disallowed nodes. In this way, we can avoid finding no node to alloc
+ * page.
+ * If we have a lock to protect task->mempolicy in read-side, we do
+ * rebind directly.
+ *
+ * step:
+ * MPOL_REBIND_ONCE - do rebind work at once
+ * MPOL_REBIND_STEP1 - set all the newly nodes
+ * MPOL_REBIND_STEP2 - clean all the disallowed nodes
+ */
+static void mpol_rebind_policy(struct mempolicy *pol, const nodemask_t *newmask,
+ enum mpol_rebind_step step)
{
if (!pol)
return;
- if (!mpol_store_user_nodemask(pol) &&
+ if (!mpol_store_user_nodemask(pol) && step == 0 &&
nodes_equal(pol->w.cpuset_mems_allowed, *newmask))
return;
- mpol_ops[pol->mode].rebind(pol, newmask);
+
+ if (step == MPOL_REBIND_STEP1 && (pol->flags & MPOL_F_REBINDING))
+ return;
+
+ if (step == MPOL_REBIND_STEP2 && !(pol->flags & MPOL_F_REBINDING))
+ BUG();
+
+ if (step == MPOL_REBIND_STEP1)
+ pol->flags |= MPOL_F_REBINDING;
+ else if (step == MPOL_REBIND_STEP2)
+ pol->flags &= ~MPOL_F_REBINDING;
+ else if (step >= MPOL_REBIND_NSTEP)
+ BUG();
+
+ mpol_ops[pol->mode].rebind(pol, newmask, step);
}
/*
@@ -349,9 +417,10 @@ static void mpol_rebind_policy(struct mempolicy *pol,
* Called with task's alloc_lock held.
*/
-void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new)
+void mpol_rebind_task(struct task_struct *tsk, const nodemask_t *new,
+ enum mpol_rebind_step step)
{
- mpol_rebind_policy(tsk->mempolicy, new);
+ mpol_rebind_policy(tsk->mempolicy, new, step);
}
/*
@@ -366,7 +435,7 @@ void mpol_rebind_mm(struct mm_struct *mm, nodemask_t *new)
down_write(&mm->mmap_sem);
for (vma = mm->mmap; vma; vma = vma->vm_next)
- mpol_rebind_policy(vma->vm_policy, new);
+ mpol_rebind_policy(vma->vm_policy, new, MPOL_REBIND_ONCE);
up_write(&mm->mmap_sem);
}
@@ -859,7 +928,7 @@ static int migrate_to_node(struct mm_struct *mm, int source, int dest,
nodes_clear(nmask);
node_set(source, nmask);
- check_range(mm, mm->mmap->vm_start, TASK_SIZE, &nmask,
+ check_range(mm, mm->mmap->vm_start, mm->task_size, &nmask,
flags | MPOL_MF_DISCONTIG_OK, &pagelist);
if (!list_empty(&pagelist))
@@ -1444,15 +1513,13 @@ static struct zonelist *policy_zonelist(gfp_t gfp, struct mempolicy *policy)
/*
* Normally, MPOL_BIND allocations are node-local within the
* allowed nodemask. However, if __GFP_THISNODE is set and the
- * current node is part of the mask, we use the zonelist for
+ * current node isn't part of the mask, we use the zonelist for
* the first node in the mask instead.
*/
if (unlikely(gfp & __GFP_THISNODE) &&
unlikely(!node_isset(nd, policy->v.nodes)))
nd = first_node(policy->v.nodes);
break;
- case MPOL_INTERLEAVE: /* should not happen */
- break;
default:
BUG();
}
@@ -1572,6 +1639,8 @@ static inline unsigned interleave_nid(struct mempolicy *pol,
* 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 get_mems_allowed()
*/
struct zonelist *huge_zonelist(struct vm_area_struct *vma, unsigned long addr,
gfp_t gfp_flags, struct mempolicy **mpol,
@@ -1617,6 +1686,7 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask)
if (!(mask && current->mempolicy))
return false;
+ task_lock(current);
mempolicy = current->mempolicy;
switch (mempolicy->mode) {
case MPOL_PREFERRED:
@@ -1636,6 +1706,7 @@ bool init_nodemask_of_mempolicy(nodemask_t *mask)
default:
BUG();
}
+ task_unlock(current);
return true;
}
@@ -1683,13 +1754,17 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr)
{
struct mempolicy *pol = get_vma_policy(current, vma, addr);
struct zonelist *zl;
+ struct page *page;
+ get_mems_allowed();
if (unlikely(pol->mode == MPOL_INTERLEAVE)) {
unsigned nid;
nid = interleave_nid(pol, vma, addr, PAGE_SHIFT);
mpol_cond_put(pol);
- return alloc_page_interleave(gfp, 0, nid);
+ page = alloc_page_interleave(gfp, 0, nid);
+ put_mems_allowed();
+ return page;
}
zl = policy_zonelist(gfp, pol);
if (unlikely(mpol_needs_cond_ref(pol))) {
@@ -1699,12 +1774,15 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr)
struct page *page = __alloc_pages_nodemask(gfp, 0,
zl, policy_nodemask(gfp, pol));
__mpol_put(pol);
+ put_mems_allowed();
return page;
}
/*
* fast path: default or task policy
*/
- return __alloc_pages_nodemask(gfp, 0, zl, policy_nodemask(gfp, pol));
+ page = __alloc_pages_nodemask(gfp, 0, zl, policy_nodemask(gfp, pol));
+ put_mems_allowed();
+ return page;
}
/**
@@ -1729,18 +1807,23 @@ alloc_page_vma(gfp_t gfp, struct vm_area_struct *vma, unsigned long addr)
struct page *alloc_pages_current(gfp_t gfp, unsigned order)
{
struct mempolicy *pol = current->mempolicy;
+ struct page *page;
if (!pol || in_interrupt() || (gfp & __GFP_THISNODE))
pol = &default_policy;
+ get_mems_allowed();
/*
* No reference counting needed for current->mempolicy
* nor system default_policy
*/
if (pol->mode == MPOL_INTERLEAVE)
- return alloc_page_interleave(gfp, order, interleave_nodes(pol));
- return __alloc_pages_nodemask(gfp, order,
+ page = alloc_page_interleave(gfp, order, interleave_nodes(pol));
+ else
+ page = __alloc_pages_nodemask(gfp, order,
policy_zonelist(gfp, pol), policy_nodemask(gfp, pol));
+ put_mems_allowed();
+ return page;
}
EXPORT_SYMBOL(alloc_pages_current);
@@ -1750,6 +1833,9 @@ EXPORT_SYMBOL(alloc_pages_current);
* with the mems_allowed returned by cpuset_mems_allowed(). This
* keeps mempolicies cpuset relative after its cpuset moves. See
* further kernel/cpuset.c update_nodemask().
+ *
+ * current's mempolicy may be rebinded by the other task(the task that changes
+ * cpuset's mems), so we needn't do rebind work for current task.
*/
/* Slow path of a mempolicy duplicate */
@@ -1759,13 +1845,24 @@ struct mempolicy *__mpol_dup(struct mempolicy *old)
if (!new)
return ERR_PTR(-ENOMEM);
+
+ /* task's mempolicy is protected by alloc_lock */
+ if (old == current->mempolicy) {
+ task_lock(current);
+ *new = *old;
+ task_unlock(current);
+ } else
+ *new = *old;
+
rcu_read_lock();
if (current_cpuset_is_being_rebound()) {
nodemask_t mems = cpuset_mems_allowed(current);
- mpol_rebind_policy(old, &mems);
+ if (new->flags & MPOL_F_REBINDING)
+ mpol_rebind_policy(new, &mems, MPOL_REBIND_STEP2);
+ else
+ mpol_rebind_policy(new, &mems, MPOL_REBIND_ONCE);
}
rcu_read_unlock();
- *new = *old;
atomic_set(&new->refcnt, 1);
return new;
}
@@ -1792,16 +1889,6 @@ struct mempolicy *__mpol_cond_copy(struct mempolicy *tompol,
return tompol;
}
-static int mpol_match_intent(const struct mempolicy *a,
- const struct mempolicy *b)
-{
- if (a->flags != b->flags)
- return 0;
- if (!mpol_store_user_nodemask(a))
- return 1;
- return nodes_equal(a->w.user_nodemask, b->w.user_nodemask);
-}
-
/* Slow path of a mempolicy comparison */
int __mpol_equal(struct mempolicy *a, struct mempolicy *b)
{
@@ -1809,8 +1896,12 @@ int __mpol_equal(struct mempolicy *a, struct mempolicy *b)
return 0;
if (a->mode != b->mode)
return 0;
- if (a->mode != MPOL_DEFAULT && !mpol_match_intent(a, b))
+ if (a->flags != b->flags)
return 0;
+ if (mpol_store_user_nodemask(a))
+ if (!nodes_equal(a->w.user_nodemask, b->w.user_nodemask))
+ return 0;
+
switch (a->mode) {
case MPOL_BIND:
/* Fall through */
@@ -2006,27 +2097,24 @@ void mpol_shared_policy_init(struct shared_policy *sp, struct mempolicy *mpol)
return;
/* contextualize the tmpfs mount point mempolicy */
new = mpol_new(mpol->mode, mpol->flags, &mpol->w.user_nodemask);
- if (IS_ERR(new)) {
- mpol_put(mpol); /* drop our ref on sb mpol */
- NODEMASK_SCRATCH_FREE(scratch);
- return; /* no valid nodemask intersection */
- }
+ if (IS_ERR(new))
+ goto free_scratch; /* no valid nodemask intersection */
task_lock(current);
ret = mpol_set_nodemask(new, &mpol->w.user_nodemask, scratch);
task_unlock(current);
mpol_put(mpol); /* drop our ref on sb mpol */
- if (ret) {
- NODEMASK_SCRATCH_FREE(scratch);
- mpol_put(new);
- return;
- }
+ if (ret)
+ goto put_free;
/* Create pseudo-vma that contains just the policy */
memset(&pvma, 0, sizeof(struct vm_area_struct));
pvma.vm_end = TASK_SIZE; /* policy covers entire file */
mpol_set_shared_policy(sp, &pvma, new); /* adds ref */
+
+put_free:
mpol_put(new); /* drop initial ref */
+free_scratch:
NODEMASK_SCRATCH_FREE(scratch);
}
}
@@ -2132,9 +2220,15 @@ void numa_default_policy(void)
* "local" is pseudo-policy: MPOL_PREFERRED with MPOL_F_LOCAL flag
* Used only for mpol_parse_str() and mpol_to_str()
*/
-#define MPOL_LOCAL (MPOL_INTERLEAVE + 1)
-static const char * const policy_types[] =
- { "default", "prefer", "bind", "interleave", "local" };
+#define MPOL_LOCAL MPOL_MAX
+static const char * const policy_modes[] =
+{
+ [MPOL_DEFAULT] = "default",
+ [MPOL_PREFERRED] = "prefer",
+ [MPOL_BIND] = "bind",
+ [MPOL_INTERLEAVE] = "interleave",
+ [MPOL_LOCAL] = "local"
+};
#ifdef CONFIG_TMPFS
@@ -2159,12 +2253,11 @@ static const char * const policy_types[] =
int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
{
struct mempolicy *new = NULL;
- unsigned short uninitialized_var(mode);
+ unsigned short mode;
unsigned short uninitialized_var(mode_flags);
nodemask_t nodes;
char *nodelist = strchr(str, ':');
char *flags = strchr(str, '=');
- int i;
int err = 1;
if (nodelist) {
@@ -2180,13 +2273,12 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
if (flags)
*flags++ = '\0'; /* terminate mode string */
- for (i = 0; i <= MPOL_LOCAL; i++) {
- if (!strcmp(str, policy_types[i])) {
- mode = i;
+ for (mode = 0; mode <= MPOL_LOCAL; mode++) {
+ if (!strcmp(str, policy_modes[mode])) {
break;
}
}
- if (i > MPOL_LOCAL)
+ if (mode > MPOL_LOCAL)
goto out;
switch (mode) {
@@ -2250,7 +2342,10 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
if (IS_ERR(new))
goto out;
- {
+ if (no_context) {
+ /* save for contextualization */
+ new->w.user_nodemask = nodes;
+ } else {
int ret;
NODEMASK_SCRATCH(scratch);
if (scratch) {
@@ -2266,10 +2361,6 @@ int mpol_parse_str(char *str, struct mempolicy **mpol, int no_context)
}
}
err = 0;
- if (no_context) {
- /* save for contextualization */
- new->w.user_nodemask = nodes;
- }
out:
/* Restore string for error message */
@@ -2338,11 +2429,11 @@ int mpol_to_str(char *buffer, int maxlen, struct mempolicy *pol, int no_context)
BUG();
}
- l = strlen(policy_types[mode]);
+ l = strlen(policy_modes[mode]);
if (buffer + maxlen < p + l + 1)
return -ENOSPC;
- strcpy(p, policy_types[mode]);
+ strcpy(p, policy_modes[mode]);
p += l;
if (flags & MPOL_MODE_FLAGS) {
generated by cgit v1.1 at 2024-12-27 03:26:13 +0000