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Date: Fri, 4 Mar 2022 10:43:20 -0800
From: Song Liu <song@...nel.org>
To: <bpf@...r.kernel.org>, <netdev@...r.kernel.org>
CC: <ast@...nel.org>, <daniel@...earbox.net>, <andrii@...nel.org>,
<kernel-team@...com>, <edumazet@...gle.com>,
Song Liu <song@...nel.org>
Subject: [PATCH bpf-next] bpf: select proper size for bpf_prog_pack
Using HPAGE_PMD_SIZE as the size for bpf_prog_pack is not ideal in some
cases. Specifically, for NUMA systems, __vmalloc_node_range requires
PMD_SIZE * num_online_nodes() to allocate huge pages. Also, if the system
does not support huge pages (i.e., with cmdline option nohugevmalloc), it
is better to use PAGE_SIZE packs.
Add logic to select proper size for bpf_prog_pack. This solution is not
ideal, as it makes assumption about the behavior of module_alloc and
__vmalloc_node_range. However, it appears to be the easiest solution as
it doesn't require changes in module_alloc and vmalloc code.
Signed-off-by: Song Liu <song@...nel.org>
---
kernel/bpf/core.c | 66 +++++++++++++++++++++++++++++++----------------
1 file changed, 44 insertions(+), 22 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ab630f773ec1..957b198364eb 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -33,6 +33,7 @@
#include <linux/extable.h>
#include <linux/log2.h>
#include <linux/bpf_verifier.h>
+#include <linux/nodemask.h>
#include <asm/barrier.h>
#include <asm/unaligned.h>
@@ -814,15 +815,9 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog,
* allocator. The prog_pack allocator uses HPAGE_PMD_SIZE page (2MB on x86)
* to host BPF programs.
*/
-#ifdef CONFIG_TRANSPARENT_HUGEPAGE
-#define BPF_PROG_PACK_SIZE HPAGE_PMD_SIZE
-#else
-#define BPF_PROG_PACK_SIZE PAGE_SIZE
-#endif
#define BPF_PROG_CHUNK_SHIFT 6
#define BPF_PROG_CHUNK_SIZE (1 << BPF_PROG_CHUNK_SHIFT)
#define BPF_PROG_CHUNK_MASK (~(BPF_PROG_CHUNK_SIZE - 1))
-#define BPF_PROG_CHUNK_COUNT (BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE)
struct bpf_prog_pack {
struct list_head list;
@@ -830,30 +825,57 @@ struct bpf_prog_pack {
unsigned long bitmap[];
};
-#define BPF_PROG_MAX_PACK_PROG_SIZE BPF_PROG_PACK_SIZE
#define BPF_PROG_SIZE_TO_NBITS(size) (round_up(size, BPF_PROG_CHUNK_SIZE) / BPF_PROG_CHUNK_SIZE)
+static size_t bpf_prog_pack_size = -1;
+
+static inline int bpf_prog_chunk_count(void)
+{
+ WARN_ON_ONCE(bpf_prog_pack_size == -1);
+ return bpf_prog_pack_size / BPF_PROG_CHUNK_SIZE;
+}
+
static DEFINE_MUTEX(pack_mutex);
static LIST_HEAD(pack_list);
static struct bpf_prog_pack *alloc_new_pack(void)
{
struct bpf_prog_pack *pack;
+ size_t size;
+ void *ptr;
- pack = kzalloc(sizeof(*pack) + BITS_TO_BYTES(BPF_PROG_CHUNK_COUNT), GFP_KERNEL);
- if (!pack)
+ if (bpf_prog_pack_size == -1) {
+ /* Test whether we can get huge pages. If not just use
+ * PAGE_SIZE packs.
+ */
+ size = PMD_SIZE * num_online_nodes();
+ ptr = module_alloc(size);
+ if (ptr && is_vm_area_hugepages(ptr)) {
+ bpf_prog_pack_size = size;
+ goto got_ptr;
+ } else {
+ bpf_prog_pack_size = PAGE_SIZE;
+ vfree(ptr);
+ }
+ }
+
+ ptr = module_alloc(bpf_prog_pack_size);
+ if (!ptr)
return NULL;
- pack->ptr = module_alloc(BPF_PROG_PACK_SIZE);
- if (!pack->ptr) {
- kfree(pack);
+got_ptr:
+ pack = kzalloc(struct_size(pack, bitmap, BITS_TO_LONGS(bpf_prog_chunk_count())),
+ GFP_KERNEL);
+ if (!pack) {
+ vfree(ptr);
return NULL;
}
- bitmap_zero(pack->bitmap, BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE);
+ pack->ptr = ptr;
+ bitmap_zero(pack->bitmap, bpf_prog_pack_size / BPF_PROG_CHUNK_SIZE);
list_add_tail(&pack->list, &pack_list);
set_vm_flush_reset_perms(pack->ptr);
- set_memory_ro((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE);
- set_memory_x((unsigned long)pack->ptr, BPF_PROG_PACK_SIZE / PAGE_SIZE);
+ set_memory_ro((unsigned long)pack->ptr, bpf_prog_pack_size / PAGE_SIZE);
+ set_memory_x((unsigned long)pack->ptr, bpf_prog_pack_size / PAGE_SIZE);
return pack;
}
@@ -864,7 +886,7 @@ static void *bpf_prog_pack_alloc(u32 size)
unsigned long pos;
void *ptr = NULL;
- if (size > BPF_PROG_MAX_PACK_PROG_SIZE) {
+ if (size > bpf_prog_pack_size) {
size = round_up(size, PAGE_SIZE);
ptr = module_alloc(size);
if (ptr) {
@@ -876,9 +898,9 @@ static void *bpf_prog_pack_alloc(u32 size)
}
mutex_lock(&pack_mutex);
list_for_each_entry(pack, &pack_list, list) {
- pos = bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0,
+ pos = bitmap_find_next_zero_area(pack->bitmap, bpf_prog_chunk_count(), 0,
nbits, 0);
- if (pos < BPF_PROG_CHUNK_COUNT)
+ if (pos < bpf_prog_chunk_count())
goto found_free_area;
}
@@ -904,12 +926,12 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr)
unsigned long pos;
void *pack_ptr;
- if (hdr->size > BPF_PROG_MAX_PACK_PROG_SIZE) {
+ if (hdr->size > bpf_prog_pack_size) {
module_memfree(hdr);
return;
}
- pack_ptr = (void *)((unsigned long)hdr & ~(BPF_PROG_PACK_SIZE - 1));
+ pack_ptr = (void *)((unsigned long)hdr & ~(bpf_prog_pack_size - 1));
mutex_lock(&pack_mutex);
list_for_each_entry(tmp, &pack_list, list) {
@@ -926,8 +948,8 @@ static void bpf_prog_pack_free(struct bpf_binary_header *hdr)
pos = ((unsigned long)hdr - (unsigned long)pack_ptr) >> BPF_PROG_CHUNK_SHIFT;
bitmap_clear(pack->bitmap, pos, nbits);
- if (bitmap_find_next_zero_area(pack->bitmap, BPF_PROG_CHUNK_COUNT, 0,
- BPF_PROG_CHUNK_COUNT, 0) == 0) {
+ if (bitmap_find_next_zero_area(pack->bitmap, bpf_prog_chunk_count(), 0,
+ bpf_prog_chunk_count(), 0) == 0) {
list_del(&pack->list);
module_memfree(pack->ptr);
kfree(pack);
--
2.30.2
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