Merging upstream version 6.8.9.

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 349 insertions, 39 deletions

diff --git a/mm/ksm.c b/mm/ksm.c
index 6a831009b4..8c001819cf 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -21,6 +21,7 @@
 #include <linux/sched.h>
 #include <linux/sched/mm.h>
 #include <linux/sched/coredump.h>
+#include <linux/sched/cputime.h>
 #include <linux/rwsem.h>
 #include <linux/pagemap.h>
 #include <linux/rmap.h>
@@ -248,6 +249,9 @@ static struct kmem_cache *rmap_item_cache;
 static struct kmem_cache *stable_node_cache;
 static struct kmem_cache *mm_slot_cache;
 
+/* Default number of pages to scan per batch */
+#define DEFAULT_PAGES_TO_SCAN 100
+
 /* The number of pages scanned */
 static unsigned long ksm_pages_scanned;
 
@@ -276,7 +280,7 @@ static unsigned int ksm_stable_node_chains_prune_millisecs = 2000;
 static int ksm_max_page_sharing = 256;
 
 /* Number of pages ksmd should scan in one batch */
-static unsigned int ksm_thread_pages_to_scan = 100;
+static unsigned int ksm_thread_pages_to_scan = DEFAULT_PAGES_TO_SCAN;
 
 /* Milliseconds ksmd should sleep between batches */
 static unsigned int ksm_thread_sleep_millisecs = 20;
@@ -297,6 +301,172 @@ unsigned long ksm_zero_pages;
 /* The number of pages that have been skipped due to "smart scanning" */
 static unsigned long ksm_pages_skipped;
 
+/* Don't scan more than max pages per batch. */
+static unsigned long ksm_advisor_max_pages_to_scan = 30000;
+
+/* Min CPU for scanning pages per scan */
+#define KSM_ADVISOR_MIN_CPU 10
+
+/* Max CPU for scanning pages per scan */
+static unsigned int ksm_advisor_max_cpu =  70;
+
+/* Target scan time in seconds to analyze all KSM candidate pages. */
+static unsigned long ksm_advisor_target_scan_time = 200;
+
+/* Exponentially weighted moving average. */
+#define EWMA_WEIGHT 30
+
+/**
+ * struct advisor_ctx - metadata for KSM advisor
+ * @start_scan: start time of the current scan
+ * @scan_time: scan time of previous scan
+ * @change: change in percent to pages_to_scan parameter
+ * @cpu_time: cpu time consumed by the ksmd thread in the previous scan
+ */
+struct advisor_ctx {
+	ktime_t start_scan;
+	unsigned long scan_time;
+	unsigned long change;
+	unsigned long long cpu_time;
+};
+static struct advisor_ctx advisor_ctx;
+
+/* Define different advisor's */
+enum ksm_advisor_type {
+	KSM_ADVISOR_NONE,
+	KSM_ADVISOR_SCAN_TIME,
+};
+static enum ksm_advisor_type ksm_advisor;
+
+#ifdef CONFIG_SYSFS
+/*
+ * Only called through the sysfs control interface:
+ */
+
+/* At least scan this many pages per batch. */
+static unsigned long ksm_advisor_min_pages_to_scan = 500;
+
+static void set_advisor_defaults(void)
+{
+	if (ksm_advisor == KSM_ADVISOR_NONE) {
+		ksm_thread_pages_to_scan = DEFAULT_PAGES_TO_SCAN;
+	} else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME) {
+		advisor_ctx = (const struct advisor_ctx){ 0 };
+		ksm_thread_pages_to_scan = ksm_advisor_min_pages_to_scan;
+	}
+}
+#endif /* CONFIG_SYSFS */
+
+static inline void advisor_start_scan(void)
+{
+	if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
+		advisor_ctx.start_scan = ktime_get();
+}
+
+/*
+ * Use previous scan time if available, otherwise use current scan time as an
+ * approximation for the previous scan time.
+ */
+static inline unsigned long prev_scan_time(struct advisor_ctx *ctx,
+					   unsigned long scan_time)
+{
+	return ctx->scan_time ? ctx->scan_time : scan_time;
+}
+
+/* Calculate exponential weighted moving average */
+static unsigned long ewma(unsigned long prev, unsigned long curr)
+{
+	return ((100 - EWMA_WEIGHT) * prev + EWMA_WEIGHT * curr) / 100;
+}
+
+/*
+ * The scan time advisor is based on the current scan rate and the target
+ * scan rate.
+ *
+ *      new_pages_to_scan = pages_to_scan * (scan_time / target_scan_time)
+ *
+ * To avoid perturbations it calculates a change factor of previous changes.
+ * A new change factor is calculated for each iteration and it uses an
+ * exponentially weighted moving average. The new pages_to_scan value is
+ * multiplied with that change factor:
+ *
+ *      new_pages_to_scan *= change facor
+ *
+ * The new_pages_to_scan value is limited by the cpu min and max values. It
+ * calculates the cpu percent for the last scan and calculates the new
+ * estimated cpu percent cost for the next scan. That value is capped by the
+ * cpu min and max setting.
+ *
+ * In addition the new pages_to_scan value is capped by the max and min
+ * limits.
+ */
+static void scan_time_advisor(void)
+{
+	unsigned int cpu_percent;
+	unsigned long cpu_time;
+	unsigned long cpu_time_diff;
+	unsigned long cpu_time_diff_ms;
+	unsigned long pages;
+	unsigned long per_page_cost;
+	unsigned long factor;
+	unsigned long change;
+	unsigned long last_scan_time;
+	unsigned long scan_time;
+
+	/* Convert scan time to seconds */
+	scan_time = div_s64(ktime_ms_delta(ktime_get(), advisor_ctx.start_scan),
+			    MSEC_PER_SEC);
+	scan_time = scan_time ? scan_time : 1;
+
+	/* Calculate CPU consumption of ksmd background thread */
+	cpu_time = task_sched_runtime(current);
+	cpu_time_diff = cpu_time - advisor_ctx.cpu_time;
+	cpu_time_diff_ms = cpu_time_diff / 1000 / 1000;
+
+	cpu_percent = (cpu_time_diff_ms * 100) / (scan_time * 1000);
+	cpu_percent = cpu_percent ? cpu_percent : 1;
+	last_scan_time = prev_scan_time(&advisor_ctx, scan_time);
+
+	/* Calculate scan time as percentage of target scan time */
+	factor = ksm_advisor_target_scan_time * 100 / scan_time;
+	factor = factor ? factor : 1;
+
+	/*
+	 * Calculate scan time as percentage of last scan time and use
+	 * exponentially weighted average to smooth it
+	 */
+	change = scan_time * 100 / last_scan_time;
+	change = change ? change : 1;
+	change = ewma(advisor_ctx.change, change);
+
+	/* Calculate new scan rate based on target scan rate. */
+	pages = ksm_thread_pages_to_scan * 100 / factor;
+	/* Update pages_to_scan by weighted change percentage. */
+	pages = pages * change / 100;
+
+	/* Cap new pages_to_scan value */
+	per_page_cost = ksm_thread_pages_to_scan / cpu_percent;
+	per_page_cost = per_page_cost ? per_page_cost : 1;
+
+	pages = min(pages, per_page_cost * ksm_advisor_max_cpu);
+	pages = max(pages, per_page_cost * KSM_ADVISOR_MIN_CPU);
+	pages = min(pages, ksm_advisor_max_pages_to_scan);
+
+	/* Update advisor context */
+	advisor_ctx.change = change;
+	advisor_ctx.scan_time = scan_time;
+	advisor_ctx.cpu_time = cpu_time;
+
+	ksm_thread_pages_to_scan = pages;
+	trace_ksm_advisor(scan_time, pages, cpu_percent);
+}
+
+static void advisor_stop_scan(void)
+{
+	if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
+		scan_time_advisor();
+}
+
 #ifdef CONFIG_NUMA
 /* Zeroed when merging across nodes is not allowed */
 static unsigned int ksm_merge_across_nodes = 1;
@@ -1099,9 +1269,9 @@ error:
 static u32 calc_checksum(struct page *page)
 {
 	u32 checksum;
-	void *addr = kmap_atomic(page);
+	void *addr = kmap_local_page(page);
 	checksum = xxhash(addr, PAGE_SIZE, 0);
-	kunmap_atomic(addr);
+	kunmap_local(addr);
 	return checksum;
 }
 
@@ -1161,8 +1331,9 @@ static int write_protect_page(struct vm_area_struct *vma, struct page *page,
 			goto out_unlock;
 		}
 
-		/* See page_try_share_anon_rmap(): clear PTE first. */
-		if (anon_exclusive && page_try_share_anon_rmap(page)) {
+		/* See folio_try_share_anon_rmap_pte(): clear PTE first. */
+		if (anon_exclusive &&
+		    folio_try_share_anon_rmap_pte(page_folio(page), page)) {
 			set_pte_at(mm, pvmw.address, pvmw.pte, entry);
 			goto out_unlock;
 		}
@@ -1199,6 +1370,7 @@ out:
 static int replace_page(struct vm_area_struct *vma, struct page *page,
 			struct page *kpage, pte_t orig_pte)
 {
+	struct folio *kfolio = page_folio(kpage);
 	struct mm_struct *mm = vma->vm_mm;
 	struct folio *folio;
 	pmd_t *pmd;
@@ -1238,15 +1410,16 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 		goto out_mn;
 	}
 	VM_BUG_ON_PAGE(PageAnonExclusive(page), page);
-	VM_BUG_ON_PAGE(PageAnon(kpage) && PageAnonExclusive(kpage), kpage);
+	VM_BUG_ON_FOLIO(folio_test_anon(kfolio) && PageAnonExclusive(kpage),
+			kfolio);
 
 	/*
 	 * No need to check ksm_use_zero_pages here: we can only have a
 	 * zero_page here if ksm_use_zero_pages was enabled already.
 	 */
 	if (!is_zero_pfn(page_to_pfn(kpage))) {
-		get_page(kpage);
-		page_add_anon_rmap(kpage, vma, addr, RMAP_NONE);
+		folio_get(kfolio);
+		folio_add_anon_rmap_pte(kfolio, kpage, vma, addr, RMAP_NONE);
 		newpte = mk_pte(kpage, vma->vm_page_prot);
 	} else {
 		/*
@@ -1277,7 +1450,7 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
 	set_pte_at_notify(mm, addr, ptep, newpte);
 
 	folio = page_folio(page);
-	page_remove_rmap(page, vma, false);
+	folio_remove_rmap_pte(folio, page, vma);
 	if (!folio_mapped(folio))
 		folio_free_swap(folio);
 	folio_put(folio);
@@ -2401,6 +2574,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
 
 	mm_slot = ksm_scan.mm_slot;
 	if (mm_slot == &ksm_mm_head) {
+		advisor_start_scan();
 		trace_ksm_start_scan(ksm_scan.seqnr, ksm_rmap_items);
 
 		/*
@@ -2558,6 +2732,8 @@ no_vmas:
 	if (mm_slot != &ksm_mm_head)
 		goto next_mm;
 
+	advisor_stop_scan();
+
 	trace_ksm_stop_scan(ksm_scan.seqnr, ksm_rmap_items);
 	ksm_scan.seqnr++;
 	return NULL;
@@ -2604,11 +2780,9 @@ static int ksm_scan_thread(void *nothing)
 			ksm_do_scan(ksm_thread_pages_to_scan);
 		mutex_unlock(&ksm_thread_mutex);
 
-		try_to_freeze();
-
 		if (ksmd_should_run()) {
 			sleep_ms = READ_ONCE(ksm_thread_sleep_millisecs);
-			wait_event_interruptible_timeout(ksm_iter_wait,
+			wait_event_freezable_timeout(ksm_iter_wait,
 				sleep_ms != READ_ONCE(ksm_thread_sleep_millisecs),
 				msecs_to_jiffies(sleep_ms));
 		} else {
@@ -2875,49 +3049,53 @@ void __ksm_exit(struct mm_struct *mm)
 	trace_ksm_exit(mm);
 }
 
-struct page *ksm_might_need_to_copy(struct page *page,
-			struct vm_area_struct *vma, unsigned long address)
+struct folio *ksm_might_need_to_copy(struct folio *folio,
+			struct vm_area_struct *vma, unsigned long addr)
 {
-	struct folio *folio = page_folio(page);
+	struct page *page = folio_page(folio, 0);
 	struct anon_vma *anon_vma = folio_anon_vma(folio);
-	struct page *new_page;
+	struct folio *new_folio;
 
-	if (PageKsm(page)) {
-		if (page_stable_node(page) &&
+	if (folio_test_large(folio))
+		return folio;
+
+	if (folio_test_ksm(folio)) {
+		if (folio_stable_node(folio) &&
 		    !(ksm_run & KSM_RUN_UNMERGE))
-			return page;	/* no need to copy it */
+			return folio;	/* no need to copy it */
 	} else if (!anon_vma) {
-		return page;		/* no need to copy it */
-	} else if (page->index == linear_page_index(vma, address) &&
+		return folio;		/* no need to copy it */
+	} else if (folio->index == linear_page_index(vma, addr) &&
 			anon_vma->root == vma->anon_vma->root) {
-		return page;		/* still no need to copy it */
+		return folio;		/* still no need to copy it */
 	}
 	if (PageHWPoison(page))
 		return ERR_PTR(-EHWPOISON);
-	if (!PageUptodate(page))
-		return page;		/* let do_swap_page report the error */
-
-	new_page = alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
-	if (new_page &&
-	    mem_cgroup_charge(page_folio(new_page), vma->vm_mm, GFP_KERNEL)) {
-		put_page(new_page);
-		new_page = NULL;
-	}
-	if (new_page) {
-		if (copy_mc_user_highpage(new_page, page, address, vma)) {
-			put_page(new_page);
-			memory_failure_queue(page_to_pfn(page), 0);
+	if (!folio_test_uptodate(folio))
+		return folio;		/* let do_swap_page report the error */
+
+	new_folio = vma_alloc_folio(GFP_HIGHUSER_MOVABLE, 0, vma, addr, false);
+	if (new_folio &&
+	    mem_cgroup_charge(new_folio, vma->vm_mm, GFP_KERNEL)) {
+		folio_put(new_folio);
+		new_folio = NULL;
+	}
+	if (new_folio) {
+		if (copy_mc_user_highpage(folio_page(new_folio, 0), page,
+								addr, vma)) {
+			folio_put(new_folio);
+			memory_failure_queue(folio_pfn(folio), 0);
 			return ERR_PTR(-EHWPOISON);
 		}
-		SetPageDirty(new_page);
-		__SetPageUptodate(new_page);
-		__SetPageLocked(new_page);
+		folio_set_dirty(new_folio);
+		__folio_mark_uptodate(new_folio);
+		__folio_set_locked(new_folio);
 #ifdef CONFIG_SWAP
 		count_vm_event(KSM_SWPIN_COPY);
 #endif
 	}
 
-	return new_page;
+	return new_folio;
 }
 
 void rmap_walk_ksm(struct folio *folio, struct rmap_walk_control *rwc)
@@ -3244,6 +3422,9 @@ static ssize_t pages_to_scan_store(struct kobject *kobj,
 	unsigned int nr_pages;
 	int err;
 
+	if (ksm_advisor != KSM_ADVISOR_NONE)
+		return -EINVAL;
+
 	err = kstrtouint(buf, 10, &nr_pages);
 	if (err)
 		return -EINVAL;
@@ -3563,6 +3744,130 @@ static ssize_t smart_scan_store(struct kobject *kobj,
 }
 KSM_ATTR(smart_scan);
 
+static ssize_t advisor_mode_show(struct kobject *kobj,
+				 struct kobj_attribute *attr, char *buf)
+{
+	const char *output;
+
+	if (ksm_advisor == KSM_ADVISOR_NONE)
+		output = "[none] scan-time";
+	else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME)
+		output = "none [scan-time]";
+
+	return sysfs_emit(buf, "%s\n", output);
+}
+
+static ssize_t advisor_mode_store(struct kobject *kobj,
+				  struct kobj_attribute *attr, const char *buf,
+				  size_t count)
+{
+	enum ksm_advisor_type curr_advisor = ksm_advisor;
+
+	if (sysfs_streq("scan-time", buf))
+		ksm_advisor = KSM_ADVISOR_SCAN_TIME;
+	else if (sysfs_streq("none", buf))
+		ksm_advisor = KSM_ADVISOR_NONE;
+	else
+		return -EINVAL;
+
+	/* Set advisor default values */
+	if (curr_advisor != ksm_advisor)
+		set_advisor_defaults();
+
+	return count;
+}
+KSM_ATTR(advisor_mode);
+
+static ssize_t advisor_max_cpu_show(struct kobject *kobj,
+				    struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%u\n", ksm_advisor_max_cpu);
+}
+
+static ssize_t advisor_max_cpu_store(struct kobject *kobj,
+				     struct kobj_attribute *attr,
+				     const char *buf, size_t count)
+{
+	int err;
+	unsigned long value;
+
+	err = kstrtoul(buf, 10, &value);
+	if (err)
+		return -EINVAL;
+
+	ksm_advisor_max_cpu = value;
+	return count;
+}
+KSM_ATTR(advisor_max_cpu);
+
+static ssize_t advisor_min_pages_to_scan_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%lu\n", ksm_advisor_min_pages_to_scan);
+}
+
+static ssize_t advisor_min_pages_to_scan_store(struct kobject *kobj,
+					struct kobj_attribute *attr,
+					const char *buf, size_t count)
+{
+	int err;
+	unsigned long value;
+
+	err = kstrtoul(buf, 10, &value);
+	if (err)
+		return -EINVAL;
+
+	ksm_advisor_min_pages_to_scan = value;
+	return count;
+}
+KSM_ATTR(advisor_min_pages_to_scan);
+
+static ssize_t advisor_max_pages_to_scan_show(struct kobject *kobj,
+					struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%lu\n", ksm_advisor_max_pages_to_scan);
+}
+
+static ssize_t advisor_max_pages_to_scan_store(struct kobject *kobj,
+					struct kobj_attribute *attr,
+					const char *buf, size_t count)
+{
+	int err;
+	unsigned long value;
+
+	err = kstrtoul(buf, 10, &value);
+	if (err)
+		return -EINVAL;
+
+	ksm_advisor_max_pages_to_scan = value;
+	return count;
+}
+KSM_ATTR(advisor_max_pages_to_scan);
+
+static ssize_t advisor_target_scan_time_show(struct kobject *kobj,
+					     struct kobj_attribute *attr, char *buf)
+{
+	return sysfs_emit(buf, "%lu\n", ksm_advisor_target_scan_time);
+}
+
+static ssize_t advisor_target_scan_time_store(struct kobject *kobj,
+					      struct kobj_attribute *attr,
+					      const char *buf, size_t count)
+{
+	int err;
+	unsigned long value;
+
+	err = kstrtoul(buf, 10, &value);
+	if (err)
+		return -EINVAL;
+	if (value < 1)
+		return -EINVAL;
+
+	ksm_advisor_target_scan_time = value;
+	return count;
+}
+KSM_ATTR(advisor_target_scan_time);
+
 static struct attribute *ksm_attrs[] = {
 	&sleep_millisecs_attr.attr,
 	&pages_to_scan_attr.attr,
@@ -3585,6 +3890,11 @@ static struct attribute *ksm_attrs[] = {
 	&use_zero_pages_attr.attr,
 	&general_profit_attr.attr,
 	&smart_scan_attr.attr,
+	&advisor_mode_attr.attr,
+	&advisor_max_cpu_attr.attr,
+	&advisor_min_pages_to_scan_attr.attr,
+	&advisor_max_pages_to_scan_attr.attr,
+	&advisor_target_scan_time_attr.attr,
 	NULL,
 };