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-rw-r--r--mm/migrate.c377
1 files changed, 253 insertions, 124 deletions
diff --git a/mm/migrate.c b/mm/migrate.c
index 7079e6b7dbe7..18ce840914f0 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -50,6 +50,7 @@
#include <linux/ptrace.h>
#include <linux/oom.h>
#include <linux/memory.h>
+#include <linux/random.h>
#include <asm/tlbflush.h>
@@ -236,20 +237,19 @@ static bool remove_migration_pte(struct page *page, struct vm_area_struct *vma,
pte = pte_mkhuge(pte);
pte = arch_make_huge_pte(pte, shift, vma->vm_flags);
- set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
if (PageAnon(new))
hugepage_add_anon_rmap(new, vma, pvmw.address);
else
page_dup_rmap(new, true);
+ set_huge_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
} else
#endif
{
- set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
-
if (PageAnon(new))
page_add_anon_rmap(new, vma, pvmw.address, false);
else
page_add_file_rmap(new, false);
+ set_pte_at(vma->vm_mm, pvmw.address, pvmw.pte, pte);
}
if (vma->vm_flags & VM_LOCKED && !PageTransCompound(new))
mlock_vma_page(new);
@@ -1084,80 +1084,6 @@ out:
return rc;
}
-
-/*
- * node_demotion[] example:
- *
- * Consider a system with two sockets. Each socket has
- * three classes of memory attached: fast, medium and slow.
- * Each memory class is placed in its own NUMA node. The
- * CPUs are placed in the node with the "fast" memory. The
- * 6 NUMA nodes (0-5) might be split among the sockets like
- * this:
- *
- * Socket A: 0, 1, 2
- * Socket B: 3, 4, 5
- *
- * When Node 0 fills up, its memory should be migrated to
- * Node 1. When Node 1 fills up, it should be migrated to
- * Node 2. The migration path start on the nodes with the
- * processors (since allocations default to this node) and
- * fast memory, progress through medium and end with the
- * slow memory:
- *
- * 0 -> 1 -> 2 -> stop
- * 3 -> 4 -> 5 -> stop
- *
- * This is represented in the node_demotion[] like this:
- *
- * { 1, // Node 0 migrates to 1
- * 2, // Node 1 migrates to 2
- * -1, // Node 2 does not migrate
- * 4, // Node 3 migrates to 4
- * 5, // Node 4 migrates to 5
- * -1} // Node 5 does not migrate
- */
-
-/*
- * Writes to this array occur without locking. Cycles are
- * not allowed: Node X demotes to Y which demotes to X...
- *
- * If multiple reads are performed, a single rcu_read_lock()
- * must be held over all reads to ensure that no cycles are
- * observed.
- */
-static int node_demotion[MAX_NUMNODES] __read_mostly =
- {[0 ... MAX_NUMNODES - 1] = NUMA_NO_NODE};
-
-/**
- * next_demotion_node() - Get the next node in the demotion path
- * @node: The starting node to lookup the next node
- *
- * Return: node id for next memory node in the demotion path hierarchy
- * from @node; NUMA_NO_NODE if @node is terminal. This does not keep
- * @node online or guarantee that it *continues* to be the next demotion
- * target.
- */
-int next_demotion_node(int node)
-{
- int target;
-
- /*
- * node_demotion[] is updated without excluding this
- * function from running. RCU doesn't provide any
- * compiler barriers, so the READ_ONCE() is required
- * to avoid compiler reordering or read merging.
- *
- * Make sure to use RCU over entire code blocks if
- * node_demotion[] reads need to be consistent.
- */
- rcu_read_lock();
- target = READ_ONCE(node_demotion[node]);
- rcu_read_unlock();
-
- return target;
-}
-
/*
* Obtain the lock on page, remove all ptes and migrate the page
* to the newly allocated page in newpage.
@@ -1413,7 +1339,7 @@ static inline int try_split_thp(struct page *page, struct page **page2,
* @mode: The migration mode that specifies the constraints for
* page migration, if any.
* @reason: The reason for page migration.
- * @ret_succeeded: Set to the number of pages migrated successfully if
+ * @ret_succeeded: Set to the number of normal pages migrated successfully if
* the caller passes a non-NULL pointer.
*
* The function returns after 10 attempts or if no pages are movable any more
@@ -1421,7 +1347,9 @@ static inline int try_split_thp(struct page *page, struct page **page2,
* It is caller's responsibility to call putback_movable_pages() to return pages
* to the LRU or free list only if ret != 0.
*
- * Returns the number of pages that were not migrated, or an error code.
+ * Returns the number of {normal page, THP, hugetlb} that were not migrated, or
+ * an error code. The number of THP splits will be considered as the number of
+ * non-migrated THP, no matter how many subpages of the THP are migrated successfully.
*/
int migrate_pages(struct list_head *from, new_page_t get_new_page,
free_page_t put_new_page, unsigned long private,
@@ -1430,6 +1358,7 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
int retry = 1;
int thp_retry = 1;
int nr_failed = 0;
+ int nr_failed_pages = 0;
int nr_succeeded = 0;
int nr_thp_succeeded = 0;
int nr_thp_failed = 0;
@@ -1441,13 +1370,16 @@ int migrate_pages(struct list_head *from, new_page_t get_new_page,
int swapwrite = current->flags & PF_SWAPWRITE;
int rc, nr_subpages;
LIST_HEAD(ret_pages);
+ LIST_HEAD(thp_split_pages);
bool nosplit = (reason == MR_NUMA_MISPLACED);
+ bool no_subpage_counting = false;
trace_mm_migrate_pages_start(mode, reason);
if (!swapwrite)
current->flags |= PF_SWAPWRITE;
+thp_subpage_migration:
for (pass = 0; pass < 10 && (retry || thp_retry); pass++) {
retry = 0;
thp_retry = 0;
@@ -1460,7 +1392,7 @@ retry:
* during migration.
*/
is_thp = PageTransHuge(page) && !PageHuge(page);
- nr_subpages = thp_nr_pages(page);
+ nr_subpages = compound_nr(page);
cond_resched();
if (PageHuge(page))
@@ -1496,18 +1428,20 @@ retry:
case -ENOSYS:
/* THP migration is unsupported */
if (is_thp) {
- if (!try_split_thp(page, &page2, from)) {
+ nr_thp_failed++;
+ if (!try_split_thp(page, &page2, &thp_split_pages)) {
nr_thp_split++;
goto retry;
}
- nr_thp_failed++;
- nr_failed += nr_subpages;
+ nr_failed_pages += nr_subpages;
break;
}
/* Hugetlb migration is unsupported */
- nr_failed++;
+ if (!no_subpage_counting)
+ nr_failed++;
+ nr_failed_pages += nr_subpages;
break;
case -ENOMEM:
/*
@@ -1516,16 +1450,19 @@ retry:
* THP NUMA faulting doesn't split THP to retry.
*/
if (is_thp && !nosplit) {
- if (!try_split_thp(page, &page2, from)) {
+ nr_thp_failed++;
+ if (!try_split_thp(page, &page2, &thp_split_pages)) {
nr_thp_split++;
goto retry;
}
- nr_thp_failed++;
- nr_failed += nr_subpages;
+ nr_failed_pages += nr_subpages;
goto out;
}
- nr_failed++;
+
+ if (!no_subpage_counting)
+ nr_failed++;
+ nr_failed_pages += nr_subpages;
goto out;
case -EAGAIN:
if (is_thp) {
@@ -1535,12 +1472,11 @@ retry:
retry++;
break;
case MIGRATEPAGE_SUCCESS:
+ nr_succeeded += nr_subpages;
if (is_thp) {
nr_thp_succeeded++;
- nr_succeeded += nr_subpages;
break;
}
- nr_succeeded++;
break;
default:
/*
@@ -1551,17 +1487,37 @@ retry:
*/
if (is_thp) {
nr_thp_failed++;
- nr_failed += nr_subpages;
+ nr_failed_pages += nr_subpages;
break;
}
- nr_failed++;
+
+ if (!no_subpage_counting)
+ nr_failed++;
+ nr_failed_pages += nr_subpages;
break;
}
}
}
- nr_failed += retry + thp_retry;
+ nr_failed += retry;
nr_thp_failed += thp_retry;
- rc = nr_failed;
+ /*
+ * Try to migrate subpages of fail-to-migrate THPs, no nr_failed
+ * counting in this round, since all subpages of a THP is counted
+ * as 1 failure in the first round.
+ */
+ if (!list_empty(&thp_split_pages)) {
+ /*
+ * Move non-migrated pages (after 10 retries) to ret_pages
+ * to avoid migrating them again.
+ */
+ list_splice_init(from, &ret_pages);
+ list_splice_init(&thp_split_pages, from);
+ no_subpage_counting = true;
+ retry = 1;
+ goto thp_subpage_migration;
+ }
+
+ rc = nr_failed + nr_thp_failed;
out:
/*
* Put the permanent failure page back to migration list, they
@@ -1570,11 +1526,11 @@ out:
list_splice(&ret_pages, from);
count_vm_events(PGMIGRATE_SUCCESS, nr_succeeded);
- count_vm_events(PGMIGRATE_FAIL, nr_failed);
+ count_vm_events(PGMIGRATE_FAIL, nr_failed_pages);
count_vm_events(THP_MIGRATION_SUCCESS, nr_thp_succeeded);
count_vm_events(THP_MIGRATION_FAIL, nr_thp_failed);
count_vm_events(THP_MIGRATION_SPLIT, nr_thp_split);
- trace_mm_migrate_pages(nr_succeeded, nr_failed, nr_thp_succeeded,
+ trace_mm_migrate_pages(nr_succeeded, nr_failed_pages, nr_thp_succeeded,
nr_thp_failed, nr_thp_split, mode, reason);
if (!swapwrite)
@@ -2516,8 +2472,7 @@ static bool migrate_vma_check_page(struct page *page)
static void migrate_vma_unmap(struct migrate_vma *migrate)
{
const unsigned long npages = migrate->npages;
- const unsigned long start = migrate->start;
- unsigned long addr, i, restore = 0;
+ unsigned long i, restore = 0;
bool allow_drain = true;
lru_add_drain();
@@ -2563,7 +2518,7 @@ static void migrate_vma_unmap(struct migrate_vma *migrate)
}
}
- for (addr = start, i = 0; i < npages && restore; addr += PAGE_SIZE, i++) {
+ for (i = 0; i < npages && restore; i++) {
struct page *page = migrate_pfn_to_page(migrate->src[i]);
if (!page || (migrate->src[i] & MIGRATE_PFN_MIGRATE))
@@ -2961,14 +2916,152 @@ void migrate_vma_finalize(struct migrate_vma *migrate)
EXPORT_SYMBOL(migrate_vma_finalize);
#endif /* CONFIG_DEVICE_PRIVATE */
+/*
+ * node_demotion[] example:
+ *
+ * Consider a system with two sockets. Each socket has
+ * three classes of memory attached: fast, medium and slow.
+ * Each memory class is placed in its own NUMA node. The
+ * CPUs are placed in the node with the "fast" memory. The
+ * 6 NUMA nodes (0-5) might be split among the sockets like
+ * this:
+ *
+ * Socket A: 0, 1, 2
+ * Socket B: 3, 4, 5
+ *
+ * When Node 0 fills up, its memory should be migrated to
+ * Node 1. When Node 1 fills up, it should be migrated to
+ * Node 2. The migration path start on the nodes with the
+ * processors (since allocations default to this node) and
+ * fast memory, progress through medium and end with the
+ * slow memory:
+ *
+ * 0 -> 1 -> 2 -> stop
+ * 3 -> 4 -> 5 -> stop
+ *
+ * This is represented in the node_demotion[] like this:
+ *
+ * { nr=1, nodes[0]=1 }, // Node 0 migrates to 1
+ * { nr=1, nodes[0]=2 }, // Node 1 migrates to 2
+ * { nr=0, nodes[0]=-1 }, // Node 2 does not migrate
+ * { nr=1, nodes[0]=4 }, // Node 3 migrates to 4
+ * { nr=1, nodes[0]=5 }, // Node 4 migrates to 5
+ * { nr=0, nodes[0]=-1 }, // Node 5 does not migrate
+ *
+ * Moreover some systems may have multiple slow memory nodes.
+ * Suppose a system has one socket with 3 memory nodes, node 0
+ * is fast memory type, and node 1/2 both are slow memory
+ * type, and the distance between fast memory node and slow
+ * memory node is same. So the migration path should be:
+ *
+ * 0 -> 1/2 -> stop
+ *
+ * This is represented in the node_demotion[] like this:
+ * { nr=2, {nodes[0]=1, nodes[1]=2} }, // Node 0 migrates to node 1 and node 2
+ * { nr=0, nodes[0]=-1, }, // Node 1 dose not migrate
+ * { nr=0, nodes[0]=-1, }, // Node 2 does not migrate
+ */
+
+/*
+ * Writes to this array occur without locking. Cycles are
+ * not allowed: Node X demotes to Y which demotes to X...
+ *
+ * If multiple reads are performed, a single rcu_read_lock()
+ * must be held over all reads to ensure that no cycles are
+ * observed.
+ */
+#define DEFAULT_DEMOTION_TARGET_NODES 15
+
+#if MAX_NUMNODES < DEFAULT_DEMOTION_TARGET_NODES
+#define DEMOTION_TARGET_NODES (MAX_NUMNODES - 1)
+#else
+#define DEMOTION_TARGET_NODES DEFAULT_DEMOTION_TARGET_NODES
+#endif
+
+struct demotion_nodes {
+ unsigned short nr;
+ short nodes[DEMOTION_TARGET_NODES];
+};
+
+static struct demotion_nodes *node_demotion __read_mostly;
+
+/**
+ * next_demotion_node() - Get the next node in the demotion path
+ * @node: The starting node to lookup the next node
+ *
+ * Return: node id for next memory node in the demotion path hierarchy
+ * from @node; NUMA_NO_NODE if @node is terminal. This does not keep
+ * @node online or guarantee that it *continues* to be the next demotion
+ * target.
+ */
+int next_demotion_node(int node)
+{
+ struct demotion_nodes *nd;
+ unsigned short target_nr, index;
+ int target;
+
+ if (!node_demotion)
+ return NUMA_NO_NODE;
+
+ nd = &node_demotion[node];
+
+ /*
+ * node_demotion[] is updated without excluding this
+ * function from running. RCU doesn't provide any
+ * compiler barriers, so the READ_ONCE() is required
+ * to avoid compiler reordering or read merging.
+ *
+ * Make sure to use RCU over entire code blocks if
+ * node_demotion[] reads need to be consistent.
+ */
+ rcu_read_lock();
+ target_nr = READ_ONCE(nd->nr);
+
+ switch (target_nr) {
+ case 0:
+ target = NUMA_NO_NODE;
+ goto out;
+ case 1:
+ index = 0;
+ break;
+ default:
+ /*
+ * If there are multiple target nodes, just select one
+ * target node randomly.
+ *
+ * In addition, we can also use round-robin to select
+ * target node, but we should introduce another variable
+ * for node_demotion[] to record last selected target node,
+ * that may cause cache ping-pong due to the changing of
+ * last target node. Or introducing per-cpu data to avoid
+ * caching issue, which seems more complicated. So selecting
+ * target node randomly seems better until now.
+ */
+ index = get_random_int() % target_nr;
+ break;
+ }
+
+ target = READ_ONCE(nd->nodes[index]);
+
+out:
+ rcu_read_unlock();
+ return target;
+}
+
#if defined(CONFIG_HOTPLUG_CPU)
/* Disable reclaim-based migration. */
static void __disable_all_migrate_targets(void)
{
- int node;
+ int node, i;
+
+ if (!node_demotion)
+ return;
- for_each_online_node(node)
- node_demotion[node] = NUMA_NO_NODE;
+ for_each_online_node(node) {
+ node_demotion[node].nr = 0;
+ for (i = 0; i < DEMOTION_TARGET_NODES; i++)
+ node_demotion[node].nodes[i] = NUMA_NO_NODE;
+ }
}
static void disable_all_migrate_targets(void)
@@ -2995,26 +3088,40 @@ static void disable_all_migrate_targets(void)
* Failing here is OK. It might just indicate
* being at the end of a chain.
*/
-static int establish_migrate_target(int node, nodemask_t *used)
+static int establish_migrate_target(int node, nodemask_t *used,
+ int best_distance)
{
- int migration_target;
+ int migration_target, index, val;
+ struct demotion_nodes *nd;
- /*
- * Can not set a migration target on a
- * node with it already set.
- *
- * No need for READ_ONCE() here since this
- * in the write path for node_demotion[].
- * This should be the only thread writing.
- */
- if (node_demotion[node] != NUMA_NO_NODE)
+ if (!node_demotion)
return NUMA_NO_NODE;
+ nd = &node_demotion[node];
+
migration_target = find_next_best_node(node, used);
if (migration_target == NUMA_NO_NODE)
return NUMA_NO_NODE;
- node_demotion[node] = migration_target;
+ /*
+ * If the node has been set a migration target node before,
+ * which means it's the best distance between them. Still
+ * check if this node can be demoted to other target nodes
+ * if they have a same best distance.
+ */
+ if (best_distance != -1) {
+ val = node_distance(node, migration_target);
+ if (val > best_distance)
+ return NUMA_NO_NODE;
+ }
+
+ index = nd->nr;
+ if (WARN_ONCE(index >= DEMOTION_TARGET_NODES,
+ "Exceeds maximum demotion target nodes\n"))
+ return NUMA_NO_NODE;
+
+ nd->nodes[index] = migration_target;
+ nd->nr++;
return migration_target;
}
@@ -3030,7 +3137,9 @@ static int establish_migrate_target(int node, nodemask_t *used)
*
* The difference here is that cycles must be avoided. If
* node0 migrates to node1, then neither node1, nor anything
- * node1 migrates to can migrate to node0.
+ * node1 migrates to can migrate to node0. Also one node can
+ * be migrated to multiple nodes if the target nodes all have
+ * a same best-distance against the source node.
*
* This function can run simultaneously with readers of
* node_demotion[]. However, it can not run simultaneously
@@ -3042,7 +3151,7 @@ static void __set_migration_target_nodes(void)
nodemask_t next_pass = NODE_MASK_NONE;
nodemask_t this_pass = NODE_MASK_NONE;
nodemask_t used_targets = NODE_MASK_NONE;
- int node;
+ int node, best_distance;
/*
* Avoid any oddities like cycles that could occur
@@ -3071,18 +3180,33 @@ again:
* multiple source nodes to share a destination.
*/
nodes_or(used_targets, used_targets, this_pass);
- for_each_node_mask(node, this_pass) {
- int target_node = establish_migrate_target(node, &used_targets);
- if (target_node == NUMA_NO_NODE)
- continue;
+ for_each_node_mask(node, this_pass) {
+ best_distance = -1;
/*
- * Visit targets from this pass in the next pass.
- * Eventually, every node will have been part of
- * a pass, and will become set in 'used_targets'.
+ * Try to set up the migration path for the node, and the target
+ * migration nodes can be multiple, so doing a loop to find all
+ * the target nodes if they all have a best node distance.
*/
- node_set(target_node, next_pass);
+ do {
+ int target_node =
+ establish_migrate_target(node, &used_targets,
+ best_distance);
+
+ if (target_node == NUMA_NO_NODE)
+ break;
+
+ if (best_distance == -1)
+ best_distance = node_distance(node, target_node);
+
+ /*
+ * Visit targets from this pass in the next pass.
+ * Eventually, every node will have been part of
+ * a pass, and will become set in 'used_targets'.
+ */
+ node_set(target_node, next_pass);
+ } while (1);
}
/*
* 'next_pass' contains nodes which became migration
@@ -3183,6 +3307,11 @@ static int __init migrate_on_reclaim_init(void)
{
int ret;
+ node_demotion = kmalloc_array(nr_node_ids,
+ sizeof(struct demotion_nodes),
+ GFP_KERNEL);
+ WARN_ON(!node_demotion);
+
ret = cpuhp_setup_state_nocalls(CPUHP_MM_DEMOTION_DEAD, "mm/demotion:offline",
NULL, migration_offline_cpu);
/*
generated by cgit v1.2.3 (git 2.39.0) at 2024-12-22 04:25:25 +0300