[PATCH v9 6/9] secretmem: add memcg accounting

[Mike Rapoport <rppt@xxxxxxxxxx>]

From: Mike Rapoport <rppt@xxxxxxxxxxxxx>

Account memory consumed by secretmem to memcg. The accounting is updated
when the memory is actually allocated and freed.

Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx>
---
 mm/filemap.c   |  3 ++-
 mm/secretmem.c | 36 +++++++++++++++++++++++++++++++++++-
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/mm/filemap.c b/mm/filemap.c
index 249cf489f5df..cf7f1dc9f4b8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -42,6 +42,7 @@
 #include <linux/psi.h>
 #include <linux/ramfs.h>
 #include <linux/page_idle.h>
+#include <linux/secretmem.h>
 #include "internal.h"
 
 #define CREATE_TRACE_POINTS
@@ -844,7 +845,7 @@ static noinline int __add_to_page_cache_locked(struct page *page,
 	page->mapping = mapping;
 	page->index = offset;
 
-	if (!huge) {
+	if (!huge && !page_is_secretmem(page)) {
 		error = mem_cgroup_charge(page, current->mm, gfp);
 		if (error)
 			goto error;
diff --git a/mm/secretmem.c b/mm/secretmem.c
index d4c44fc568a4..abf6ecdf70cb 100644
--- a/mm/secretmem.c
+++ b/mm/secretmem.c
@@ -18,6 +18,7 @@
 #include <linux/memblock.h>
 #include <linux/pseudo_fs.h>
 #include <linux/secretmem.h>
+#include <linux/memcontrol.h>
 #include <linux/set_memory.h>
 #include <linux/sched/signal.h>
 
@@ -50,6 +51,32 @@ struct secretmem_ctx {
 
 static struct cma *secretmem_cma;
 
+static int secretmem_account_pages(struct page *page, gfp_t gfp, int order)
+{
+	int err;
+
+	err = memcg_kmem_charge_page(page, gfp, order);
+	if (err)
+		return err;
+
+	/*
+	 * seceremem caches are unreclaimable kernel allocations, so treat
+	 * them as unreclaimable slab memory for VM statistics purposes
+	 */
+	mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
+			    PAGE_SIZE << order);
+
+	return 0;
+}
+
+static void secretmem_unaccount_pages(struct page *page, int order)
+{
+
+	mod_node_page_state(page_pgdat(page), NR_SLAB_UNRECLAIMABLE_B,
+			    -PAGE_SIZE << order);
+	memcg_kmem_uncharge_page(page, order);
+}
+
 static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
 {
 	unsigned long nr_pages = (1 << PMD_PAGE_ORDER);
@@ -62,10 +89,14 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
 	if (!page)
 		return -ENOMEM;
 
-	err = set_direct_map_invalid_noflush(page, nr_pages);
+	err = secretmem_account_pages(page, gfp, PMD_PAGE_ORDER);
 	if (err)
 		goto err_cma_release;
 
+	err = set_direct_map_invalid_noflush(page, nr_pages);
+	if (err)
+		goto err_memcg_uncharge;
+
 	addr = (unsigned long)page_address(page);
 	err = gen_pool_add(pool, addr, PMD_SIZE, NUMA_NO_NODE);
 	if (err)
@@ -82,6 +113,8 @@ static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
 	 * won't fail
 	 */
 	set_direct_map_default_noflush(page, nr_pages);
+err_memcg_uncharge:
+	secretmem_unaccount_pages(page, PMD_PAGE_ORDER);
 err_cma_release:
 	cma_release(secretmem_cma, page, nr_pages);
 	return err;
@@ -312,6 +345,7 @@ static void secretmem_cleanup_chunk(struct gen_pool *pool,
 	int i;
 
 	set_direct_map_default_noflush(page, nr_pages);
+	secretmem_unaccount_pages(page, PMD_PAGE_ORDER);
 
 	for (i = 0; i < nr_pages; i++)
 		clear_highpage(page + i);
-- 
2.28.0