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-rw-r--r--include/linux/mmzone.h8
-rw-r--r--mm/vmscan.c112
2 files changed, 42 insertions, 78 deletions
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index 337956748976..a4889c9d4055 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -443,18 +443,14 @@ enum {
struct lru_gen_mm_state {
/* set to max_seq after each iteration */
unsigned long seq;
- /* where the current iteration continues (inclusive) */
+ /* where the current iteration continues after */
struct list_head *head;
- /* where the last iteration ended (exclusive) */
+ /* where the last iteration ended before */
struct list_head *tail;
- /* to wait for the last page table walker to finish */
- struct wait_queue_head wait;
/* Bloom filters flip after each iteration */
unsigned long *filters[NR_BLOOM_FILTERS];
/* the mm stats for debugging */
unsigned long stats[NR_HIST_GENS][NR_MM_STATS];
- /* the number of concurrent page table walkers */
- int nr_walkers;
};
struct lru_gen_mm_walk {
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 2eb5862e99ec..8c05f4c288ce 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3450,18 +3450,13 @@ void lru_gen_del_mm(struct mm_struct *mm)
for_each_node(nid) {
struct lruvec *lruvec = get_lruvec(memcg, nid);
- /* where the last iteration ended (exclusive) */
+ /* where the current iteration continues after */
+ if (lruvec->mm_state.head == &mm->lru_gen.list)
+ lruvec->mm_state.head = lruvec->mm_state.head->prev;
+
+ /* where the last iteration ended before */
if (lruvec->mm_state.tail == &mm->lru_gen.list)
lruvec->mm_state.tail = lruvec->mm_state.tail->next;
-
- /* where the current iteration continues (inclusive) */
- if (lruvec->mm_state.head != &mm->lru_gen.list)
- continue;
-
- lruvec->mm_state.head = lruvec->mm_state.head->next;
- /* the deletion ends the current iteration */
- if (lruvec->mm_state.head == &mm_list->fifo)
- WRITE_ONCE(lruvec->mm_state.seq, lruvec->mm_state.seq + 1);
}
list_del_init(&mm->lru_gen.list);
@@ -3557,68 +3552,54 @@ static bool iterate_mm_list(struct lruvec *lruvec, struct lru_gen_mm_walk *walk,
struct mm_struct **iter)
{
bool first = false;
- bool last = true;
+ bool last = false;
struct mm_struct *mm = NULL;
struct mem_cgroup *memcg = lruvec_memcg(lruvec);
struct lru_gen_mm_list *mm_list = get_mm_list(memcg);
struct lru_gen_mm_state *mm_state = &lruvec->mm_state;
/*
- * There are four interesting cases for this page table walker:
- * 1. It tries to start a new iteration of mm_list with a stale max_seq;
- * there is nothing left to do.
- * 2. It's the first of the current generation, and it needs to reset
- * the Bloom filter for the next generation.
- * 3. It reaches the end of mm_list, and it needs to increment
- * mm_state->seq; the iteration is done.
- * 4. It's the last of the current generation, and it needs to reset the
- * mm stats counters for the next generation.
+ * mm_state->seq is incremented after each iteration of mm_list. There
+ * are three interesting cases for this page table walker:
+ * 1. It tries to start a new iteration with a stale max_seq: there is
+ * nothing left to do.
+ * 2. It started the next iteration: it needs to reset the Bloom filter
+ * so that a fresh set of PTE tables can be recorded.
+ * 3. It ended the current iteration: it needs to reset the mm stats
+ * counters and tell its caller to increment max_seq.
*/
spin_lock(&mm_list->lock);
VM_WARN_ON_ONCE(mm_state->seq + 1 < walk->max_seq);
- VM_WARN_ON_ONCE(*iter && mm_state->seq > walk->max_seq);
- VM_WARN_ON_ONCE(*iter && !mm_state->nr_walkers);
- if (walk->max_seq <= mm_state->seq) {
- if (!*iter)
- last = false;
+ if (walk->max_seq <= mm_state->seq)
goto done;
- }
- if (!mm_state->nr_walkers) {
- VM_WARN_ON_ONCE(mm_state->head && mm_state->head != &mm_list->fifo);
+ if (!mm_state->head)
+ mm_state->head = &mm_list->fifo;
- mm_state->head = mm_list->fifo.next;
+ if (mm_state->head == &mm_list->fifo)
first = true;
- }
-
- while (!mm && mm_state->head != &mm_list->fifo) {
- mm = list_entry(mm_state->head, struct mm_struct, lru_gen.list);
+ do {
mm_state->head = mm_state->head->next;
+ if (mm_state->head == &mm_list->fifo) {
+ WRITE_ONCE(mm_state->seq, mm_state->seq + 1);
+ last = true;
+ break;
+ }
/* force scan for those added after the last iteration */
- if (!mm_state->tail || mm_state->tail == &mm->lru_gen.list) {
- mm_state->tail = mm_state->head;
+ if (!mm_state->tail || mm_state->tail == mm_state->head) {
+ mm_state->tail = mm_state->head->next;
walk->force_scan = true;
}
+ mm = list_entry(mm_state->head, struct mm_struct, lru_gen.list);
if (should_skip_mm(mm, walk))
mm = NULL;
- }
-
- if (mm_state->head == &mm_list->fifo)
- WRITE_ONCE(mm_state->seq, mm_state->seq + 1);
+ } while (!mm);
done:
- if (*iter && !mm)
- mm_state->nr_walkers--;
- if (!*iter && mm)
- mm_state->nr_walkers++;
-
- if (mm_state->nr_walkers)
- last = false;
-
if (*iter || last)
reset_mm_stats(lruvec, walk, last);
@@ -3646,9 +3627,9 @@ static bool iterate_mm_list_nowalk(struct lruvec *lruvec, unsigned long max_seq)
VM_WARN_ON_ONCE(mm_state->seq + 1 < max_seq);
- if (max_seq > mm_state->seq && !mm_state->nr_walkers) {
- VM_WARN_ON_ONCE(mm_state->head && mm_state->head != &mm_list->fifo);
-
+ if (max_seq > mm_state->seq) {
+ mm_state->head = NULL;
+ mm_state->tail = NULL;
WRITE_ONCE(mm_state->seq, mm_state->seq + 1);
reset_mm_stats(lruvec, NULL, true);
success = true;
@@ -4248,10 +4229,6 @@ restart:
walk_pmd_range(&val, addr, next, args);
- /* a racy check to curtail the waiting time */
- if (wq_has_sleeper(&walk->lruvec->mm_state.wait))
- return 1;
-
if (need_resched() || walk->batched >= MAX_LRU_BATCH) {
end = (addr | ~PUD_MASK) + 1;
goto done;
@@ -4284,8 +4261,14 @@ static void walk_mm(struct lruvec *lruvec, struct mm_struct *mm, struct lru_gen_
walk->next_addr = FIRST_USER_ADDRESS;
do {
+ DEFINE_MAX_SEQ(lruvec);
+
err = -EBUSY;
+ /* another thread might have called inc_max_seq() */
+ if (walk->max_seq != max_seq)
+ break;
+
/* folio_update_gen() requires stable folio_memcg() */
if (!mem_cgroup_trylock_pages(memcg))
break;
@@ -4518,25 +4501,12 @@ static bool try_to_inc_max_seq(struct lruvec *lruvec, unsigned long max_seq,
success = iterate_mm_list(lruvec, walk, &mm);
if (mm)
walk_mm(lruvec, mm, walk);
-
- cond_resched();
} while (mm);
done:
- if (!success) {
- if (sc->priority <= DEF_PRIORITY - 2)
- wait_event_killable(lruvec->mm_state.wait,
- max_seq < READ_ONCE(lrugen->max_seq));
- return false;
- }
+ if (success)
+ inc_max_seq(lruvec, can_swap, force_scan);
- VM_WARN_ON_ONCE(max_seq != READ_ONCE(lrugen->max_seq));
-
- inc_max_seq(lruvec, can_swap, force_scan);
- /* either this sees any waiters or they will see updated max_seq */
- if (wq_has_sleeper(&lruvec->mm_state.wait))
- wake_up_all(&lruvec->mm_state.wait);
-
- return true;
+ return success;
}
/******************************************************************************
@@ -6173,7 +6143,6 @@ void lru_gen_init_lruvec(struct lruvec *lruvec)
INIT_LIST_HEAD(&lrugen->folios[gen][type][zone]);
lruvec->mm_state.seq = MIN_NR_GENS;
- init_waitqueue_head(&lruvec->mm_state.wait);
}
#ifdef CONFIG_MEMCG
@@ -6206,7 +6175,6 @@ void lru_gen_exit_memcg(struct mem_cgroup *memcg)
for_each_node(nid) {
struct lruvec *lruvec = get_lruvec(memcg, nid);
- VM_WARN_ON_ONCE(lruvec->mm_state.nr_walkers);
VM_WARN_ON_ONCE(memchr_inv(lruvec->lrugen.nr_pages, 0,
sizeof(lruvec->lrugen.nr_pages)));
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-29 00:11:44 +0100