[RFC v15.1 3/8] mm/damon/vaddr: Support DAMON-based Operation Schemes

[SeongJae Park]

From: SeongJae Park <sjp...@amazon.de>

This commit makes DAMON's default primitives for virtual address spaces
to support DAMON-based Operation Schemes (DAMOS) by implementing actions
application functions and registering it to the monitoring context.  The
implementation simply links 'madvise()' for related DAMOS actions.  That
is, 'madvise(MADV_WILLNEED)' is called for 'WILLNEED' DAMOS action and
similar for other actions ('COLD', 'PAGEOUT', 'HUGEPAGE', 'NOHUGEPAGE').

So, the kernel space DAMON users can now use the DAMON-based
optimizations with only small amount of code.

Signed-off-by: SeongJae Park <sjp...@amazon.de>
---
 include/linux/damon.h |  2 ++
 mm/damon/vaddr.c      | 56 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)

diff --git a/include/linux/damon.h b/include/linux/damon.h
index cfcd399da134..8988238cb29e 100644
--- a/include/linux/damon.h
+++ b/include/linux/damon.h
@@ -362,6 +362,8 @@ void damon_va_prepare_access_checks(struct damon_ctx *ctx);
 unsigned int damon_va_check_accesses(struct damon_ctx *ctx);
 bool damon_va_target_valid(void *t);
 void damon_va_cleanup(struct damon_ctx *ctx);
+int damon_va_apply_scheme(struct damon_ctx *context, struct damon_target *t,
+               struct damon_region *r, struct damos *scheme);
 void damon_va_set_primitives(struct damon_ctx *ctx);
 
 #endif /* CONFIG_DAMON_VADDR */
diff --git a/mm/damon/vaddr.c b/mm/damon/vaddr.c
index 8ee48a4abc17..ebf4720c057a 100644
--- a/mm/damon/vaddr.c
+++ b/mm/damon/vaddr.c
@@ -7,6 +7,7 @@
 
 #define pr_fmt(fmt) "damon-va: " fmt
 
+#include <asm-generic/mman-common.h>
 #include <linux/damon.h>
 #include <linux/mm.h>
 #include <linux/mmu_notifier.h>
@@ -572,6 +573,60 @@ void damon_va_cleanup(struct damon_ctx *ctx)
        }
 }
 
+#ifndef CONFIG_ADVISE_SYSCALLS
+static int damos_madvise(struct damon_target *target, struct damon_region *r,
+                       int behavior)
+{
+       return -EINVAL;
+}
+#else
+static int damos_madvise(struct damon_target *target, struct damon_region *r,
+                       int behavior)
+{
+       struct mm_struct *mm;
+       int ret = -ENOMEM;
+
+       mm = damon_get_mm(target);
+       if (!mm)
+               goto out;
+
+       ret = do_madvise(mm, PAGE_ALIGN(r->ar.start),
+                       PAGE_ALIGN(r->ar.end - r->ar.start), behavior);
+       mmput(mm);
+out:
+       return ret;
+}
+#endif /* CONFIG_ADVISE_SYSCALLS */
+
+int damon_va_apply_scheme(struct damon_ctx *ctx, struct damon_target *t,
+               struct damon_region *r, struct damos *scheme)
+{
+       int madv_action;
+
+       switch (scheme->action) {
+       case DAMOS_WILLNEED:
+               madv_action = MADV_WILLNEED;
+               break;
+       case DAMOS_COLD:
+               madv_action = MADV_COLD;
+               break;
+       case DAMOS_PAGEOUT:
+               madv_action = MADV_PAGEOUT;
+               break;
+       case DAMOS_HUGEPAGE:
+               madv_action = MADV_HUGEPAGE;
+               break;
+       case DAMOS_NOHUGEPAGE:
+               madv_action = MADV_NOHUGEPAGE;
+               break;
+       default:
+               pr_warn("Wrong action %d\n", scheme->action);
+               return -EINVAL;
+       }
+
+       return damos_madvise(t, r, madv_action);
+}
+
 void damon_va_set_primitives(struct damon_ctx *ctx)
 {
        ctx->primitive.init_target_regions = damon_va_init_regions;
@@ -581,6 +636,7 @@ void damon_va_set_primitives(struct damon_ctx *ctx)
        ctx->primitive.reset_aggregated = NULL;
        ctx->primitive.target_valid = damon_va_target_valid;
        ctx->primitive.cleanup = damon_va_cleanup;
+       ctx->primitive.apply_scheme = damon_va_apply_scheme;
 }
 
 #include "vaddr-test.h"
-- 
2.17.1