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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 v8 32/34] bpf: eliminate rlimit-based memory accounting infra for bpf maps
Date:   Tue, 24 Nov 2020 19:01:17 -0800
Message-ID: <20201125030119.2864302-33-guro@fb.com>
In-Reply-To: <20201125030119.2864302-1-guro@fb.com>
References: <20201125030119.2864302-1-guro@fb.com>
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Precedence: bulk

Remove rlimit-based accounting infrastructure code, which is not used
anymore.

To provide a backward compatibility, use an approximation of the
bpf map memory footprint as a "memlock" value, available to a user
via map info. The approximation is based on the maximal number of
elements and key and value sizes.

Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
---
 include/linux/bpf.h                           | 12 ---
 kernel/bpf/syscall.c                          | 94 +++----------------
 .../selftests/bpf/progs/bpf_iter_bpf_map.c    |  2 +-
 .../selftests/bpf/progs/map_ptr_kern.c        |  7 --
 4 files changed, 16 insertions(+), 99 deletions(-)

diff --git a/include/linux/bpf.h b/include/linux/bpf.h
index b11436cb9e3d..c9322adedd50 100644
--- a/include/linux/bpf.h
+++ b/include/linux/bpf.h
@@ -137,11 +137,6 @@ struct bpf_map_ops {
 	const struct bpf_iter_seq_info *iter_seq_info;
 };
=20
-struct bpf_map_memory {
-	u32 pages;
-	struct user_struct *user;
-};
-
 struct bpf_map {
 	/* The first two cachelines with read-mostly members of which some
 	 * are also accessed in fast-path (e.g. ops, max_entries).
@@ -162,7 +157,6 @@ struct bpf_map {
 	u32 btf_key_type_id;
 	u32 btf_value_type_id;
 	struct btf *btf;
-	struct bpf_map_memory memory;
 #ifdef CONFIG_MEMCG_KMEM
 	struct mem_cgroup *memcg;
 #endif
@@ -1223,12 +1217,6 @@ void bpf_map_inc_with_uref(struct bpf_map *map);
 struct bpf_map * __must_check bpf_map_inc_not_zero(struct bpf_map *map);
 void bpf_map_put_with_uref(struct bpf_map *map);
 void bpf_map_put(struct bpf_map *map);
-int bpf_map_charge_memlock(struct bpf_map *map, u32 pages);
-void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages);
-int bpf_map_charge_init(struct bpf_map_memory *mem, u64 size);
-void bpf_map_charge_finish(struct bpf_map_memory *mem);
-void bpf_map_charge_move(struct bpf_map_memory *dst,
-			 struct bpf_map_memory *src);
 void *bpf_map_area_alloc(u64 size, int numa_node);
 void *bpf_map_area_mmapable_alloc(u64 size, int numa_node);
 void bpf_map_area_free(void *base);
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4b514bb5cd70..3dadf34c3dd0 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -343,77 +343,6 @@ void bpf_map_init_from_attr(struct bpf_map *map, uni=
on bpf_attr *attr)
 	map->numa_node =3D bpf_map_attr_numa_node(attr);
 }
=20
-static int bpf_charge_memlock(struct user_struct *user, u32 pages)
-{
-	unsigned long memlock_limit =3D rlimit(RLIMIT_MEMLOCK) >> PAGE_SHIFT;
-
-	if (atomic_long_add_return(pages, &user->locked_vm) > memlock_limit) {
-		atomic_long_sub(pages, &user->locked_vm);
-		return -EPERM;
-	}
-	return 0;
-}
-
-static void bpf_uncharge_memlock(struct user_struct *user, u32 pages)
-{
-	if (user)
-		atomic_long_sub(pages, &user->locked_vm);
-}
-
-int bpf_map_charge_init(struct bpf_map_memory *mem, u64 size)
-{
-	u32 pages =3D round_up(size, PAGE_SIZE) >> PAGE_SHIFT;
-	struct user_struct *user;
-	int ret;
-
-	if (size >=3D U32_MAX - PAGE_SIZE)
-		return -E2BIG;
-
-	user =3D get_current_user();
-	ret =3D bpf_charge_memlock(user, pages);
-	if (ret) {
-		free_uid(user);
-		return ret;
-	}
-
-	mem->pages =3D pages;
-	mem->user =3D user;
-
-	return 0;
-}
-
-void bpf_map_charge_finish(struct bpf_map_memory *mem)
-{
-	bpf_uncharge_memlock(mem->user, mem->pages);
-	free_uid(mem->user);
-}
-
-void bpf_map_charge_move(struct bpf_map_memory *dst,
-			 struct bpf_map_memory *src)
-{
-	*dst =3D *src;
-
-	/* Make sure src will not be used for the redundant uncharging. */
-	memset(src, 0, sizeof(struct bpf_map_memory));
-}
-
-int bpf_map_charge_memlock(struct bpf_map *map, u32 pages)
-{
-	int ret;
-
-	ret =3D bpf_charge_memlock(map->memory.user, pages);
-	if (ret)
-		return ret;
-	map->memory.pages +=3D pages;
-	return ret;
-}
-
-void bpf_map_uncharge_memlock(struct bpf_map *map, u32 pages)
-{
-	bpf_uncharge_memlock(map->memory.user, pages);
-	map->memory.pages -=3D pages;
-}
-
 static int bpf_map_alloc_id(struct bpf_map *map)
 {
 	int id;
@@ -533,14 +462,11 @@ static void bpf_map_release_memcg(struct bpf_map *m=
ap)
 static void bpf_map_free_deferred(struct work_struct *work)
 {
 	struct bpf_map *map =3D container_of(work, struct bpf_map, work);
-	struct bpf_map_memory mem;
=20
-	bpf_map_charge_move(&mem, &map->memory);
 	security_bpf_map_free(map);
 	bpf_map_release_memcg(map);
 	/* implementation dependent freeing */
 	map->ops->map_free(map);
-	bpf_map_charge_finish(&mem);
 }
=20
 static void bpf_map_put_uref(struct bpf_map *map)
@@ -601,6 +527,19 @@ static fmode_t map_get_sys_perms(struct bpf_map *map=
, struct fd f)
 }
=20
 #ifdef CONFIG_PROC_FS
+/* Provides an approximation of the map's memory footprint.
+ * Used only to provide a backward compatibility and display
+ * a reasonable "memlock" info.
+ */
+static unsigned long bpf_map_memory_footprint(struct bpf_map *map)
+{
+	unsigned long size;
+
+	size =3D round_up(map->key_size + bpf_map_value_size(map), 8);
+
+	return round_up(map->max_entries * size, PAGE_SIZE);
+}
+
 static void bpf_map_show_fdinfo(struct seq_file *m, struct file *filp)
 {
 	const struct bpf_map *map =3D filp->private_data;
@@ -619,7 +558,7 @@ static void bpf_map_show_fdinfo(struct seq_file *m, s=
truct file *filp)
 		   "value_size:\t%u\n"
 		   "max_entries:\t%u\n"
 		   "map_flags:\t%#x\n"
-		   "memlock:\t%llu\n"
+		   "memlock:\t%lu\n"
 		   "map_id:\t%u\n"
 		   "frozen:\t%u\n",
 		   map->map_type,
@@ -627,7 +566,7 @@ static void bpf_map_show_fdinfo(struct seq_file *m, s=
truct file *filp)
 		   map->value_size,
 		   map->max_entries,
 		   map->map_flags,
-		   map->memory.pages * 1ULL << PAGE_SHIFT,
+		   bpf_map_memory_footprint(map),
 		   map->id,
 		   READ_ONCE(map->frozen));
 	if (type) {
@@ -870,7 +809,6 @@ static int map_check_btf(struct bpf_map *map, const s=
truct btf *btf,
 static int map_create(union bpf_attr *attr)
 {
 	int numa_node =3D bpf_map_attr_numa_node(attr);
-	struct bpf_map_memory mem;
 	struct bpf_map *map;
 	int f_flags;
 	int err;
@@ -969,9 +907,7 @@ static int map_create(union bpf_attr *attr)
 	security_bpf_map_free(map);
 free_map:
 	btf_put(map->btf);
-	bpf_map_charge_move(&mem, &map->memory);
 	map->ops->map_free(map);
-	bpf_map_charge_finish(&mem);
 	return err;
 }
=20
diff --git a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c b/tools=
/testing/selftests/bpf/progs/bpf_iter_bpf_map.c
index 08651b23edba..b83b5d2e17dc 100644
--- a/tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c
+++ b/tools/testing/selftests/bpf/progs/bpf_iter_bpf_map.c
@@ -23,6 +23,6 @@ int dump_bpf_map(struct bpf_iter__bpf_map *ctx)
=20
 	BPF_SEQ_PRINTF(seq, "%8u %8ld %8ld %10lu\n", map->id, map->refcnt.count=
er,
 		       map->usercnt.counter,
-		       map->memory.user->locked_vm.counter);
+		       0LLU);
 	return 0;
 }
diff --git a/tools/testing/selftests/bpf/progs/map_ptr_kern.c b/tools/tes=
ting/selftests/bpf/progs/map_ptr_kern.c
index c325405751e2..d8850bc6a9f1 100644
--- a/tools/testing/selftests/bpf/progs/map_ptr_kern.c
+++ b/tools/testing/selftests/bpf/progs/map_ptr_kern.c
@@ -26,17 +26,12 @@ __u32 g_line =3D 0;
 		return 0;	\
 })
=20
-struct bpf_map_memory {
-	__u32 pages;
-} __attribute__((preserve_access_index));
-
 struct bpf_map {
 	enum bpf_map_type map_type;
 	__u32 key_size;
 	__u32 value_size;
 	__u32 max_entries;
 	__u32 id;
-	struct bpf_map_memory memory;
 } __attribute__((preserve_access_index));
=20
 static inline int check_bpf_map_fields(struct bpf_map *map, __u32 key_si=
ze,
@@ -47,7 +42,6 @@ static inline int check_bpf_map_fields(struct bpf_map *=
map, __u32 key_size,
 	VERIFY(map->value_size =3D=3D value_size);
 	VERIFY(map->max_entries =3D=3D max_entries);
 	VERIFY(map->id > 0);
-	VERIFY(map->memory.pages > 0);
=20
 	return 1;
 }
@@ -60,7 +54,6 @@ static inline int check_bpf_map_ptr(struct bpf_map *ind=
irect,
 	VERIFY(indirect->value_size =3D=3D direct->value_size);
 	VERIFY(indirect->max_entries =3D=3D direct->max_entries);
 	VERIFY(indirect->id =3D=3D direct->id);
-	VERIFY(indirect->memory.pages =3D=3D direct->memory.pages);
=20
 	return 1;
 }
--=20
2.26.2