[bpf-next,v9,03/34] mm: introduce page memcg flags

Message ID	20201201215900.3569844-4-guro@fb.com
State	New
Headers	show Return-Path: <netdev-owner@kernel.org> From: Roman Gushchin <guro@fb.com> To: <bpf@vger.kernel.org> CC: <ast@kernel.org>, <daniel@iogearbox.net>, <netdev@vger.kernel.org>, <andrii@kernel.org>, <akpm@linux-foundation.org>, <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>, <kernel-team@fb.com> Subject: [PATCH bpf-next v9 03/34] mm: introduce page memcg flags Date: Tue, 1 Dec 2020 13:58:29 -0800 Message-ID: <20201201215900.3569844-4-guro@fb.com> In-Reply-To: <20201201215900.3569844-1-guro@fb.com> References: <20201201215900.3569844-1-guro@fb.com> Content-Type: text/plain Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Precedence: bulk
Series	bpf: switch to memcg-based memory accounting \| expand [bpf-next,v9,00/34] bpf: switch to memcg-based memory accounting [bpf-next,v9,01/34] mm: memcontrol: use helpers to read page's memcg data [bpf-next,v9,02/34] mm: memcontrol/slab: use helpers to access slab page's memcg_data [bpf-next,v9,03/34] mm: introduce page memcg flags [bpf-next,v9,04/34] mm: convert page kmemcg type to a page memcg flag [bpf-next,v9,05/34] bpf: memcg-based memory accounting for bpf progs [bpf-next,v9,06/34] bpf: prepare for memcg-based memory accounting for bpf maps [bpf-next,v9,07/34] bpf: memcg-based memory accounting for bpf maps [bpf-next,v9,08/34] bpf: refine memcg-based memory accounting for arraymap maps [bpf-next,v9,09/34] bpf: refine memcg-based memory accounting for cpumap maps [bpf-next,v9,10/34] bpf: memcg-based memory accounting for cgroup storage maps [bpf-next,v9,11/34] bpf: refine memcg-based memory accounting for devmap maps [bpf-next,v9,12/34] bpf: refine memcg-based memory accounting for hashtab maps [bpf-next,v9,13/34] bpf: memcg-based memory accounting for lpm_trie maps [bpf-next,v9,14/34] bpf: memcg-based memory accounting for bpf ringbuffer [bpf-next,v9,15/34] bpf: memcg-based memory accounting for bpf local storage maps [bpf-next,v9,16/34] bpf: refine memcg-based memory accounting for sockmap and sockhash maps [bpf-next,v9,17/34] bpf: refine memcg-based memory accounting for xskmap maps [bpf-next,v9,18/34] bpf: eliminate rlimit-based memory accounting for arraymap maps [bpf-next,v9,19/34] bpf: eliminate rlimit-based memory accounting for bpf_struct_ops maps [bpf-next,v9,20/34] bpf: eliminate rlimit-based memory accounting for cpumap maps [bpf-next,v9,21/34] bpf: eliminate rlimit-based memory accounting for cgroup storage maps [bpf-next,v9,22/34] bpf: eliminate rlimit-based memory accounting for devmap maps [bpf-next,v9,23/34] bpf: eliminate rlimit-based memory accounting for hashtab maps [bpf-next,v9,24/34] bpf: eliminate rlimit-based memory accounting for lpm_trie maps [bpf-next,v9,25/34] bpf: eliminate rlimit-based memory accounting for queue_stack_maps maps [bpf-next,v9,26/34] bpf: eliminate rlimit-based memory accounting for reuseport_array maps [bpf-next,v9,27/34] bpf: eliminate rlimit-based memory accounting for bpf ringbuffer [bpf-next,v9,28/34] bpf: eliminate rlimit-based memory accounting for sockmap and sockhash maps [bpf-next,v9,29/34] bpf: eliminate rlimit-based memory accounting for stackmap maps [bpf-next,v9,30/34] bpf: eliminate rlimit-based memory accounting for xskmap maps [bpf-next,v9,31/34] bpf: eliminate rlimit-based memory accounting for bpf local storage maps [bpf-next,v9,32/34] bpf: eliminate rlimit-based memory accounting infra for bpf maps [bpf-next,v9,33/34] bpf: eliminate rlimit-based memory accounting for bpf progs [bpf-next,v9,34/34] bpf: samples: do not touch RLIMIT_MEMLOCK

Message ID

20201201215900.3569844-4-guro@fb.com

State

New

Headers

From: Roman Gushchin <guro@fb.com>
To: <bpf@vger.kernel.org>
CC: <ast@kernel.org>, <daniel@iogearbox.net>, <netdev@vger.kernel.org>,
	<andrii@kernel.org>, <akpm@linux-foundation.org>,
	<linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
	<kernel-team@fb.com>
Subject: [PATCH bpf-next v9 03/34] mm: introduce page memcg flags
Date: Tue, 1 Dec 2020 13:58:29 -0800
Message-ID: <20201201215900.3569844-4-guro@fb.com>
In-Reply-To: <20201201215900.3569844-1-guro@fb.com>
References: <20201201215900.3569844-1-guro@fb.com>
Content-Type: text/plain
Content-Transfer-Encoding: quoted-printable
MIME-Version: 1.0
Precedence: bulk

Series

bpf: switch to memcg-based memory accounting | expand

Commit Message

Roman Gushchin Dec. 1, 2020, 9:58 p.m. UTC

The lowest bit in page->memcg_data is used to distinguish between struct
memory_cgroup pointer and a pointer to a objcgs array.  All checks and
modifications of this bit are open-coded.

Let's formalize it using page memcg flags, defined in enum
page_memcg_data_flags.

Additional flags might be added later.

Link: https://lkml.kernel.org/r/20201027001657.3398190-4-guro@fb.com
Signed-off-by: Roman Gushchin <guro@fb.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 include/linux/memcontrol.h | 32 ++++++++++++++++++++------------
 1 file changed, 20 insertions(+), 12 deletions(-)

diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
index c7ac0a5b8989..99a4841d658b 100644
--- a/include/linux/memcontrol.h
+++ b/include/linux/memcontrol.h
@@ -343,6 +343,15 @@  struct mem_cgroup {
 
 extern struct mem_cgroup *root_mem_cgroup;
 
+enum page_memcg_data_flags {
+	/* page->memcg_data is a pointer to an objcgs vector */
+	MEMCG_DATA_OBJCGS = (1UL << 0),
+	/* the next bit after the last actual flag */
+	__NR_MEMCG_DATA_FLAGS  = (1UL << 1),
+};
+
+#define MEMCG_DATA_FLAGS_MASK (__NR_MEMCG_DATA_FLAGS - 1)
+
 /*
  * page_memcg - get the memory cgroup associated with a page
  * @page: a pointer to the page struct
@@ -404,13 +413,7 @@  static inline struct mem_cgroup *page_memcg_check(struct page *page)
 	 */
 	unsigned long memcg_data = READ_ONCE(page->memcg_data);
 
-	/*
-	 * The lowest bit set means that memcg isn't a valid
-	 * memcg pointer, but a obj_cgroups pointer.
-	 * In this case the page is shared and doesn't belong
-	 * to any specific memory cgroup.
-	 */
-	if (memcg_data & 0x1UL)
+	if (memcg_data & MEMCG_DATA_OBJCGS)
 		return NULL;
 
 	return (struct mem_cgroup *)memcg_data;
@@ -429,7 +432,11 @@  static inline struct mem_cgroup *page_memcg_check(struct page *page)
  */
 static inline struct obj_cgroup **page_objcgs(struct page *page)
 {
-	return (struct obj_cgroup **)(READ_ONCE(page->memcg_data) & ~0x1UL);
+	unsigned long memcg_data = READ_ONCE(page->memcg_data);
+
+	VM_BUG_ON_PAGE(memcg_data && !(memcg_data & MEMCG_DATA_OBJCGS), page);
+
+	return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
 }
 
 /*
@@ -444,10 +451,10 @@  static inline struct obj_cgroup **page_objcgs_check(struct page *page)
 {
 	unsigned long memcg_data = READ_ONCE(page->memcg_data);
 
-	if (memcg_data && (memcg_data & 0x1UL))
-		return (struct obj_cgroup **)(memcg_data & ~0x1UL);
+	if (!memcg_data || !(memcg_data & MEMCG_DATA_OBJCGS))
+		return NULL;
 
-	return NULL;
+	return (struct obj_cgroup **)(memcg_data & ~MEMCG_DATA_FLAGS_MASK);
 }
 
 /*
@@ -460,7 +467,8 @@  static inline struct obj_cgroup **page_objcgs_check(struct page *page)
 static inline bool set_page_objcgs(struct page *page,
 					struct obj_cgroup **objcgs)
 {
-	return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs | 0x1UL);
+	return !cmpxchg(&page->memcg_data, 0, (unsigned long)objcgs |
+			MEMCG_DATA_OBJCGS);
 }
 #else
 static inline struct obj_cgroup **page_objcgs(struct page *page)

[bpf-next,v9,03/34] mm: introduce page memcg flags

Commit Message

Patch