1 files changed, 351 insertions, 0 deletions
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
new file mode 100644
index 0000000000..909db25efb
--- /dev/null
+++ b/mm/damon/paddr.c
@@ -0,0 +1,351 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * DAMON Primitives for The Physical Address Space
+ *
+ * Author: SeongJae Park <sj@kernel.org>
+ */
+
+#define pr_fmt(fmt) "damon-pa: " fmt
+
+#include <linux/mmu_notifier.h>
+#include <linux/page_idle.h>
+#include <linux/pagemap.h>
+#include <linux/rmap.h>
+#include <linux/swap.h>
+
+#include "../internal.h"
+#include "ops-common.h"
+
+static bool __damon_pa_mkold(struct folio *folio, struct vm_area_struct *vma,
+		unsigned long addr, void *arg)
+{
+	DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, addr, 0);
+
+	while (page_vma_mapped_walk(&pvmw)) {
+		addr = pvmw.address;
+		if (pvmw.pte)
+			damon_ptep_mkold(pvmw.pte, vma, addr);
+		else
+			damon_pmdp_mkold(pvmw.pmd, vma, addr);
+	}
+	return true;
+}
+
+static void damon_pa_mkold(unsigned long paddr)
+{
+	struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
+	struct rmap_walk_control rwc = {
+		.rmap_one = __damon_pa_mkold,
+		.anon_lock = folio_lock_anon_vma_read,
+	};
+	bool need_lock;
+
+	if (!folio)
+		return;
+
+	if (!folio_mapped(folio) || !folio_raw_mapping(folio)) {
+		folio_set_idle(folio);
+		goto out;
+	}
+
+	need_lock = !folio_test_anon(folio) || folio_test_ksm(folio);
+	if (need_lock && !folio_trylock(folio))
+		goto out;
+
+	rmap_walk(folio, &rwc);
+
+	if (need_lock)
+		folio_unlock(folio);
+
+out:
+	folio_put(folio);
+}
+
+static void __damon_pa_prepare_access_check(struct damon_region *r)
+{
+	r->sampling_addr = damon_rand(r->ar.start, r->ar.end);
+
+	damon_pa_mkold(r->sampling_addr);
+}
+
+static void damon_pa_prepare_access_checks(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	struct damon_region *r;
+
+	damon_for_each_target(t, ctx) {
+		damon_for_each_region(r, t)
+			__damon_pa_prepare_access_check(r);
+	}
+}
+
+static bool __damon_pa_young(struct folio *folio, struct vm_area_struct *vma,
+		unsigned long addr, void *arg)
+{
+	bool *accessed = arg;
+	DEFINE_FOLIO_VMA_WALK(pvmw, folio, vma, addr, 0);
+
+	*accessed = false;
+	while (page_vma_mapped_walk(&pvmw)) {
+		addr = pvmw.address;
+		if (pvmw.pte) {
+			*accessed = pte_young(ptep_get(pvmw.pte)) ||
+				!folio_test_idle(folio) ||
+				mmu_notifier_test_young(vma->vm_mm, addr);
+		} else {
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+			*accessed = pmd_young(pmdp_get(pvmw.pmd)) ||
+				!folio_test_idle(folio) ||
+				mmu_notifier_test_young(vma->vm_mm, addr);
+#else
+			WARN_ON_ONCE(1);
+#endif	/* CONFIG_TRANSPARENT_HUGEPAGE */
+		}
+		if (*accessed) {
+			page_vma_mapped_walk_done(&pvmw);
+			break;
+		}
+	}
+
+	/* If accessed, stop walking */
+	return *accessed == false;
+}
+
+static bool damon_pa_young(unsigned long paddr, unsigned long *folio_sz)
+{
+	struct folio *folio = damon_get_folio(PHYS_PFN(paddr));
+	bool accessed = false;
+	struct rmap_walk_control rwc = {
+		.arg = &accessed,
+		.rmap_one = __damon_pa_young,
+		.anon_lock = folio_lock_anon_vma_read,
+	};
+	bool need_lock;
+
+	if (!folio)
+		return false;
+
+	if (!folio_mapped(folio) || !folio_raw_mapping(folio)) {
+		if (folio_test_idle(folio))
+			accessed = false;
+		else
+			accessed = true;
+		goto out;
+	}
+
+	need_lock = !folio_test_anon(folio) || folio_test_ksm(folio);
+	if (need_lock && !folio_trylock(folio))
+		goto out;
+
+	rmap_walk(folio, &rwc);
+
+	if (need_lock)
+		folio_unlock(folio);
+
+out:
+	*folio_sz = folio_size(folio);
+	folio_put(folio);
+	return accessed;
+}
+
+static void __damon_pa_check_access(struct damon_region *r)
+{
+	static unsigned long last_addr;
+	static unsigned long last_folio_sz = PAGE_SIZE;
+	static bool last_accessed;
+
+	/* If the region is in the last checked page, reuse the result */
+	if (ALIGN_DOWN(last_addr, last_folio_sz) ==
+				ALIGN_DOWN(r->sampling_addr, last_folio_sz)) {
+		if (last_accessed)
+			r->nr_accesses++;
+		return;
+	}
+
+	last_accessed = damon_pa_young(r->sampling_addr, &last_folio_sz);
+	if (last_accessed)
+		r->nr_accesses++;
+
+	last_addr = r->sampling_addr;
+}
+
+static unsigned int damon_pa_check_accesses(struct damon_ctx *ctx)
+{
+	struct damon_target *t;
+	struct damon_region *r;
+	unsigned int max_nr_accesses = 0;
+
+	damon_for_each_target(t, ctx) {
+		damon_for_each_region(r, t) {
+			__damon_pa_check_access(r);
+			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
+		}
+	}
+
+	return max_nr_accesses;
+}
+
+static bool __damos_pa_filter_out(struct damos_filter *filter,
+		struct folio *folio)
+{
+	bool matched = false;
+	struct mem_cgroup *memcg;
+
+	switch (filter->type) {
+	case DAMOS_FILTER_TYPE_ANON:
+		matched = folio_test_anon(folio);
+		break;
+	case DAMOS_FILTER_TYPE_MEMCG:
+		rcu_read_lock();
+		memcg = folio_memcg_check(folio);
+		if (!memcg)
+			matched = false;
+		else
+			matched = filter->memcg_id == mem_cgroup_id(memcg);
+		rcu_read_unlock();
+		break;
+	default:
+		break;
+	}
+
+	return matched == filter->matching;
+}
+
+/*
+ * damos_pa_filter_out - Return true if the page should be filtered out.
+ */
+static bool damos_pa_filter_out(struct damos *scheme, struct folio *folio)
+{
+	struct damos_filter *filter;
+
+	damos_for_each_filter(filter, scheme) {
+		if (__damos_pa_filter_out(filter, folio))
+			return true;
+	}
+	return false;
+}
+
+static unsigned long damon_pa_pageout(struct damon_region *r, struct damos *s)
+{
+	unsigned long addr, applied;
+	LIST_HEAD(folio_list);
+
+	for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
+		struct folio *folio = damon_get_folio(PHYS_PFN(addr));
+
+		if (!folio)
+			continue;
+
+		if (damos_pa_filter_out(s, folio))
+			goto put_folio;
+
+		folio_clear_referenced(folio);
+		folio_test_clear_young(folio);
+		if (!folio_isolate_lru(folio))
+			goto put_folio;
+		if (folio_test_unevictable(folio))
+			folio_putback_lru(folio);
+		else
+			list_add(&folio->lru, &folio_list);
+put_folio:
+		folio_put(folio);
+	}
+	applied = reclaim_pages(&folio_list);
+	cond_resched();
+	return applied * PAGE_SIZE;
+}
+
+static inline unsigned long damon_pa_mark_accessed_or_deactivate(
+		struct damon_region *r, struct damos *s, bool mark_accessed)
+{
+	unsigned long addr, applied = 0;
+
+	for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
+		struct folio *folio = damon_get_folio(PHYS_PFN(addr));
+
+		if (!folio)
+			continue;
+
+		if (damos_pa_filter_out(s, folio))
+			goto put_folio;
+
+		if (mark_accessed)
+			folio_mark_accessed(folio);
+		else
+			folio_deactivate(folio);
+		applied += folio_nr_pages(folio);
+put_folio:
+		folio_put(folio);
+	}
+	return applied * PAGE_SIZE;
+}
+
+static unsigned long damon_pa_mark_accessed(struct damon_region *r,
+	struct damos *s)
+{
+	return damon_pa_mark_accessed_or_deactivate(r, s, true);
+}
+
+static unsigned long damon_pa_deactivate_pages(struct damon_region *r,
+	struct damos *s)
+{
+	return damon_pa_mark_accessed_or_deactivate(r, s, false);
+}
+
+static unsigned long damon_pa_apply_scheme(struct damon_ctx *ctx,
+		struct damon_target *t, struct damon_region *r,
+		struct damos *scheme)
+{
+	switch (scheme->action) {
+	case DAMOS_PAGEOUT:
+		return damon_pa_pageout(r, scheme);
+	case DAMOS_LRU_PRIO:
+		return damon_pa_mark_accessed(r, scheme);
+	case DAMOS_LRU_DEPRIO:
+		return damon_pa_deactivate_pages(r, scheme);
+	case DAMOS_STAT:
+		break;
+	default:
+		/* DAMOS actions that not yet supported by 'paddr'. */
+		break;
+	}
+	return 0;
+}
+
+static int damon_pa_scheme_score(struct damon_ctx *context,
+		struct damon_target *t, struct damon_region *r,
+		struct damos *scheme)
+{
+	switch (scheme->action) {
+	case DAMOS_PAGEOUT:
+		return damon_cold_score(context, r, scheme);
+	case DAMOS_LRU_PRIO:
+		return damon_hot_score(context, r, scheme);
+	case DAMOS_LRU_DEPRIO:
+		return damon_cold_score(context, r, scheme);
+	default:
+		break;
+	}
+
+	return DAMOS_MAX_SCORE;
+}
+
+static int __init damon_pa_initcall(void)
+{
+	struct damon_operations ops = {
+		.id = DAMON_OPS_PADDR,
+		.init = NULL,
+		.update = NULL,
+		.prepare_access_checks = damon_pa_prepare_access_checks,
+		.check_accesses = damon_pa_check_accesses,
+		.reset_aggregated = NULL,
+		.target_valid = NULL,
+		.cleanup = NULL,
+		.apply_scheme = damon_pa_apply_scheme,
+		.get_scheme_score = damon_pa_scheme_score,
+	};
+
+	return damon_register_ops(&ops);
+};
+
+subsys_initcall(damon_pa_initcall);