1 files changed, 273 insertions, 0 deletions
diff --git a/mm/damon/paddr.c b/mm/damon/paddr.c
new file mode 100644
index 000000000000..a496d6f203d6
--- /dev/null
+++ b/mm/damon/paddr.c
@@ -0,0 +1,273 @@
+// 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 "prmtv-common.h"
+
+static bool __damon_pa_mkold(struct page *page, struct vm_area_struct *vma,
+		unsigned long addr, void *arg)
+{
+	struct page_vma_mapped_walk pvmw = {
+		.page = page,
+		.vma = vma,
+		.address = addr,
+	};
+
+	while (page_vma_mapped_walk(&pvmw)) {
+		addr = pvmw.address;
+		if (pvmw.pte)
+			damon_ptep_mkold(pvmw.pte, vma->vm_mm, addr);
+		else
+			damon_pmdp_mkold(pvmw.pmd, vma->vm_mm, addr);
+	}
+	return true;
+}
+
+static void damon_pa_mkold(unsigned long paddr)
+{
+	struct page *page = damon_get_page(PHYS_PFN(paddr));
+	struct rmap_walk_control rwc = {
+		.rmap_one = __damon_pa_mkold,
+		.anon_lock = page_lock_anon_vma_read,
+	};
+	bool need_lock;
+
+	if (!page)
+		return;
+
+	if (!page_mapped(page) || !page_rmapping(page)) {
+		set_page_idle(page);
+		goto out;
+	}
+
+	need_lock = !PageAnon(page) || PageKsm(page);
+	if (need_lock && !trylock_page(page))
+		goto out;
+
+	rmap_walk(page, &rwc);
+
+	if (need_lock)
+		unlock_page(page);
+
+out:
+	put_page(page);
+}
+
+static void __damon_pa_prepare_access_check(struct damon_ctx *ctx,
+					    struct damon_region *r)
+{
+	r->sampling_addr = damon_rand(r->ar.start, r->ar.end);
+
+	damon_pa_mkold(r->sampling_addr);
+}
+
+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(ctx, r);
+	}
+}
+
+struct damon_pa_access_chk_result {
+	unsigned long page_sz;
+	bool accessed;
+};
+
+static bool __damon_pa_young(struct page *page, struct vm_area_struct *vma,
+		unsigned long addr, void *arg)
+{
+	struct damon_pa_access_chk_result *result = arg;
+	struct page_vma_mapped_walk pvmw = {
+		.page = page,
+		.vma = vma,
+		.address = addr,
+	};
+
+	result->accessed = false;
+	result->page_sz = PAGE_SIZE;
+	while (page_vma_mapped_walk(&pvmw)) {
+		addr = pvmw.address;
+		if (pvmw.pte) {
+			result->accessed = pte_young(*pvmw.pte) ||
+				!page_is_idle(page) ||
+				mmu_notifier_test_young(vma->vm_mm, addr);
+		} else {
+#ifdef CONFIG_TRANSPARENT_HUGEPAGE
+			result->accessed = pmd_young(*pvmw.pmd) ||
+				!page_is_idle(page) ||
+				mmu_notifier_test_young(vma->vm_mm, addr);
+			result->page_sz = ((1UL) << HPAGE_PMD_SHIFT);
+#else
+			WARN_ON_ONCE(1);
+#endif	/* CONFIG_TRANSPARENT_HUGEPAGE */
+		}
+		if (result->accessed) {
+			page_vma_mapped_walk_done(&pvmw);
+			break;
+		}
+	}
+
+	/* If accessed, stop walking */
+	return !result->accessed;
+}
+
+static bool damon_pa_young(unsigned long paddr, unsigned long *page_sz)
+{
+	struct page *page = damon_get_page(PHYS_PFN(paddr));
+	struct damon_pa_access_chk_result result = {
+		.page_sz = PAGE_SIZE,
+		.accessed = false,
+	};
+	struct rmap_walk_control rwc = {
+		.arg = &result,
+		.rmap_one = __damon_pa_young,
+		.anon_lock = page_lock_anon_vma_read,
+	};
+	bool need_lock;
+
+	if (!page)
+		return false;
+
+	if (!page_mapped(page) || !page_rmapping(page)) {
+		if (page_is_idle(page))
+			result.accessed = false;
+		else
+			result.accessed = true;
+		put_page(page);
+		goto out;
+	}
+
+	need_lock = !PageAnon(page) || PageKsm(page);
+	if (need_lock && !trylock_page(page)) {
+		put_page(page);
+		return NULL;
+	}
+
+	rmap_walk(page, &rwc);
+
+	if (need_lock)
+		unlock_page(page);
+	put_page(page);
+
+out:
+	*page_sz = result.page_sz;
+	return result.accessed;
+}
+
+static void __damon_pa_check_access(struct damon_ctx *ctx,
+				    struct damon_region *r)
+{
+	static unsigned long last_addr;
+	static unsigned long last_page_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_page_sz) ==
+				ALIGN_DOWN(r->sampling_addr, last_page_sz)) {
+		if (last_accessed)
+			r->nr_accesses++;
+		return;
+	}
+
+	last_accessed = damon_pa_young(r->sampling_addr, &last_page_sz);
+	if (last_accessed)
+		r->nr_accesses++;
+
+	last_addr = r->sampling_addr;
+}
+
+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(ctx, r);
+			max_nr_accesses = max(r->nr_accesses, max_nr_accesses);
+		}
+	}
+
+	return max_nr_accesses;
+}
+
+bool damon_pa_target_valid(void *t)
+{
+	return true;
+}
+
+int damon_pa_apply_scheme(struct damon_ctx *ctx, struct damon_target *t,
+		struct damon_region *r, struct damos *scheme)
+{
+	unsigned long addr;
+	LIST_HEAD(page_list);
+
+	if (scheme->action != DAMOS_PAGEOUT)
+		return -EINVAL;
+
+	for (addr = r->ar.start; addr < r->ar.end; addr += PAGE_SIZE) {
+		struct page *page = damon_get_page(PHYS_PFN(addr));
+
+		if (!page)
+			continue;
+
+		ClearPageReferenced(page);
+		test_and_clear_page_young(page);
+		if (isolate_lru_page(page)) {
+			put_page(page);
+			continue;
+		}
+		if (PageUnevictable(page)) {
+			putback_lru_page(page);
+		} else {
+			list_add(&page->lru, &page_list);
+			put_page(page);
+		}
+	}
+	reclaim_pages(&page_list);
+	cond_resched();
+	return 0;
+}
+
+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_pageout_score(context, r, scheme);
+	default:
+		break;
+	}
+
+	return DAMOS_MAX_SCORE;
+}
+
+void damon_pa_set_primitives(struct damon_ctx *ctx)
+{
+	ctx->primitive.init = NULL;
+	ctx->primitive.update = NULL;
+	ctx->primitive.prepare_access_checks = damon_pa_prepare_access_checks;
+	ctx->primitive.check_accesses = damon_pa_check_accesses;
+	ctx->primitive.reset_aggregated = NULL;
+	ctx->primitive.target_valid = damon_pa_target_valid;
+	ctx->primitive.cleanup = NULL;
+	ctx->primitive.apply_scheme = damon_pa_apply_scheme;
+	ctx->primitive.get_scheme_score = damon_pa_scheme_score;
+}