A private node is invisible to the tiering/demotion hierarchy by default: memory-tiers.c never includes it, so reclaim never demotes onto it.
Add NODE_PRIVATE_CAP_DEMOTION to opt a private node into demotion. When set, memory-tiers adds the node to the demotion set and reclaim's demote path may target it (allocating from the private zonelist). Demotion is driven by reclaim, so CAP_DEMOTION requires CAP_RECLAIM. Otherwise the node can either fill up and drive odd system-wide OOM behavior, or demotion doesn't work (nothing can demote from the node). Signed-off-by: Gregory Price <[email protected]> --- drivers/base/node.c | 5 +++++ include/linux/node_private.h | 30 +++++++++++++++++++++++++++++ mm/memory-tiers.c | 37 +++++++++++++++++++++++++++--------- mm/vmscan.c | 4 ++++ 4 files changed, 67 insertions(+), 9 deletions(-) diff --git a/drivers/base/node.c b/drivers/base/node.c index 94cd51f51b7e8..3d61ca1b805dc 100644 --- a/drivers/base/node.c +++ b/drivers/base/node.c @@ -896,6 +896,11 @@ int node_private_register(int nid, struct node_private *np) if (!np || !node_possible(nid)) return -EINVAL; + /* Demotion is driven by reclaim, so it requires reclaim. */ + if ((np->caps & NODE_PRIVATE_CAP_DEMOTION) && + !(np->caps & NODE_PRIVATE_CAP_RECLAIM)) + return -EINVAL; + mutex_lock(&node_private_lock); mem_hotplug_begin(); diff --git a/include/linux/node_private.h b/include/linux/node_private.h index 7b617b1fa9c28..87b03444b2c97 100644 --- a/include/linux/node_private.h +++ b/include/linux/node_private.h @@ -15,6 +15,7 @@ struct page; #define NODE_PRIVATE_CAP_RECLAIM (1UL << 0) /* allow mm reclaim */ #define NODE_PRIVATE_CAP_USER_NUMA (1UL << 1) /* allow mempolicy */ #define NODE_PRIVATE_CAP_HOTUNPLUG (1UL << 2) /* allow hot-unplug */ +#define NODE_PRIVATE_CAP_DEMOTION (1UL << 3) /* allow tiering demotion */ /** * struct node_private - Per-node container for N_MEMORY_PRIVATE nodes @@ -118,6 +119,30 @@ static inline bool node_allows_hotunplug(int nid) return ret; } +/** + * node_allows_demotion - may kernel tiering demote to this node? + * @nid: the node to test + * + * Governs whether a private node participates in the demotion hierarchy. + * Demotion accumulates pages on the node, so CAP_DEMOTION requires CAP_RECLAIM + * (enforced at registration) as a safety valve. + * + * return: true for normal nodes and private nodes opted into CAP_DEMOTION. + */ +static inline bool node_allows_demotion(int nid) +{ + struct node_private *np; + bool ret; + + if (!node_state(nid, N_MEMORY_PRIVATE)) + return true; + rcu_read_lock(); + np = rcu_dereference(NODE_DATA(nid)->node_private); + ret = np && (np->caps & NODE_PRIVATE_CAP_DEMOTION); + rcu_read_unlock(); + return ret; +} + #else /* !CONFIG_NUMA */ static inline bool folio_is_private_node(struct folio *folio) @@ -150,6 +175,11 @@ static inline bool node_allows_hotunplug(int nid) return true; } +static inline bool node_allows_demotion(int nid) +{ + return true; +} + #endif /* CONFIG_NUMA */ #if defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG) diff --git a/mm/memory-tiers.c b/mm/memory-tiers.c index 25e121851b586..c673080d153e4 100644 --- a/mm/memory-tiers.c +++ b/mm/memory-tiers.c @@ -7,6 +7,7 @@ #include <linux/memory-tiers.h> #include <linux/notifier.h> #include <linux/sched/sysctl.h> +#include <linux/node_private.h> #include "internal.h" @@ -317,6 +318,21 @@ void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) rcu_read_unlock(); } +/* Tiering set: N_MEMORY | (N_MEMORY_PRIVATE w/ CAP_DEMOTION) */ +static nodemask_t tierable_nodes; + +static void update_tierable_nodes(void) +{ + int node; + + lockdep_assert_held_once(&memory_tier_lock); + + tierable_nodes = node_states[N_MEMORY]; + for_each_node_state(node, N_MEMORY_PRIVATE) + if (node_allows_demotion(node)) + node_set(node, tierable_nodes); +} + /** * next_demotion_node() - Get the next node in the demotion path * @node: The starting node to lookup the next node @@ -330,7 +346,7 @@ void node_get_allowed_targets(pg_data_t *pgdat, nodemask_t *targets) int next_demotion_node(int node, const nodemask_t *allowed_mask) { struct demotion_nodes *nd; - nodemask_t mask; + nodemask_t mask, tierable; if (!node_demotion) return NUMA_NO_NODE; @@ -370,7 +386,8 @@ int next_demotion_node(int node, const nodemask_t *allowed_mask) * closest demotion target. */ nodes_complement(mask, *allowed_mask); - return find_next_best_node_in(node, &mask, &node_states[N_MEMORY]); + tierable = tierable_nodes; + return find_next_best_node_in(node, &mask, &tierable); } static void disable_all_demotion_targets(void) @@ -378,7 +395,7 @@ static void disable_all_demotion_targets(void) struct memory_tier *memtier; int node; - for_each_node_state(node, N_MEMORY) { + for_each_node_mask(node, tierable_nodes) { node_demotion[node].preferred = NODE_MASK_NONE; /* * We are holding memory_tier_lock, it is safe @@ -401,7 +418,7 @@ static void dump_demotion_targets(void) { int node; - for_each_node_state(node, N_MEMORY) { + for_each_node_mask(node, tierable_nodes) { struct memory_tier *memtier = __node_get_memory_tier(node); nodemask_t preferred = node_demotion[node].preferred; @@ -435,9 +452,10 @@ static void establish_demotion_targets(void) if (!node_demotion) return; + update_tierable_nodes(); disable_all_demotion_targets(); - for_each_node_state(node, N_MEMORY) { + for_each_node_mask(node, tierable_nodes) { best_distance = -1; nd = &node_demotion[node]; @@ -455,7 +473,7 @@ static void establish_demotion_targets(void) * nodelist to skip list so that we find the best node from the * memtier nodelist. */ - nodes_andnot(tier_nodes, node_states[N_MEMORY], tier_nodes); + nodes_andnot(tier_nodes, tierable_nodes, tier_nodes); /* * Find all the nodes in the memory tier node list of same best distance. @@ -464,7 +482,7 @@ static void establish_demotion_targets(void) */ do { target = find_next_best_node_in(node, &tier_nodes, - &node_states[N_MEMORY]); + &tierable_nodes); if (target == NUMA_NO_NODE) break; @@ -503,7 +521,7 @@ static void establish_demotion_targets(void) * allocation to a set of nodes that is closer the above selected * preferred node. */ - lower_tier = node_states[N_MEMORY]; + lower_tier = tierable_nodes; list_for_each_entry(memtier, &memory_tiers, list) { /* * Keep removing current tier from lower_tier nodes, @@ -550,7 +568,8 @@ static struct memory_tier *set_node_memory_tier(int node) lockdep_assert_held_once(&memory_tier_lock); - if (!node_state(node, N_MEMORY)) + /* Include N_MEMORY and N_MEMORY_PRIVATE with CAP_DEMOTION */ + if (!node_state(node, N_MEMORY) && !node_allows_demotion(node)) return ERR_PTR(-EINVAL); mt_calc_adistance(node, &adist); diff --git a/mm/vmscan.c b/mm/vmscan.c index f1722693ac2db..b617f7cd1e716 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -963,6 +963,10 @@ static struct folio *alloc_demote_folio(struct folio *src, mtc = (struct migration_target_control *)private; + if (mtc->nmask && + nodes_intersects(*mtc->nmask, node_states[N_MEMORY_PRIVATE])) + mtc->alloc_flags = ALLOC_ZONELIST_PRIVATE; + /* * make sure we allocate from the target node first also trying to * demote or reclaim pages from the target node via kswapd if we are -- 2.53.0-Meta
