linux-kernel - [PATCH 05/13] mm: Move memcg stack accounting to account_kernel

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Message-Id: <31f2e076a21321eedd71babb1a4791c5ad171a20.1466036668.git.luto@kernel.org>
Date:	Wed, 15 Jun 2016 17:28:27 -0700
From:	Andy Lutomirski <luto@...nel.org>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	x86@...nel.org, Borislav Petkov <bp@...en8.de>
Cc:	Nadav Amit <nadav.amit@...il.com>,
	Kees Cook <keescook@...omium.org>,
	Brian Gerst <brgerst@...il.com>,
	"kernel-hardening@...ts.openwall.com" 
	<kernel-hardening@...ts.openwall.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Josh Poimboeuf <jpoimboe@...hat.com>,
	Andy Lutomirski <luto@...nel.org>,
	Vladimir Davydov <vdavydov@...tuozzo.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org
Subject: [PATCH 05/13] mm: Move memcg stack accounting to account_kernel_stack

We should account for stacks regardless of stack size.  Move it into
account_kernel_stack.

Fixes: 12580e4b54ba8 ("mm: memcontrol: report kernel stack usage in cgroup2 memory.stat")
Cc: Vladimir Davydov <vdavydov@...tuozzo.com>
Cc: Johannes Weiner <hannes@...xchg.org>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: linux-mm@...ck.org
Signed-off-by: Andy Lutomirski <luto@...nel.org>
---
 kernel/fork.c | 15 ++++++---------
 1 file changed, 6 insertions(+), 9 deletions(-)

diff --git a/kernel/fork.c b/kernel/fork.c
index 95bebde59d79..59e52f2120a3 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -165,20 +165,12 @@ static struct thread_info *alloc_thread_info_node(struct task_struct *tsk,
 	struct page *page = alloc_kmem_pages_node(node, THREADINFO_GFP,
 						  THREAD_SIZE_ORDER);
 
-	if (page)
-		memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK,
-					    1 << THREAD_SIZE_ORDER);
-
 	return page ? page_address(page) : NULL;
 }
 
 static inline void free_thread_info(struct thread_info *ti)
 {
-	struct page *page = virt_to_page(ti);
-
-	memcg_kmem_update_page_stat(page, MEMCG_KERNEL_STACK,
-				    -(1 << THREAD_SIZE_ORDER));
-	__free_kmem_pages(page, THREAD_SIZE_ORDER);
+	free_kmem_pages((unsigned long)ti, THREAD_SIZE_ORDER);
 }
 # else
 static struct kmem_cache *thread_info_cache;
@@ -227,6 +219,11 @@ static void account_kernel_stack(struct thread_info *ti, int account)
 
 	mod_zone_page_state(zone, NR_KERNEL_STACK,
 			    THREAD_SIZE / PAGE_SIZE * account);
+
+	/* All stack pages belong to the same memcg. */
+	memcg_kmem_update_page_stat(
+		virt_to_page(ti), MEMCG_KERNEL_STACK,
+		account * (THREAD_SIZE / PAGE_SIZE));
 }
 
 void free_task(struct task_struct *tsk)
-- 
2.7.4