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.
Fixes: 57631054fae6 ("bpf: Introduce bpf_prog_pack allocator")
Signed-off-by: Song Liu <song@xxxxxxxxxx>
---
Changes v3 => v4:
1. Fix a race condition reported by kernel test robot
<oliver.sang@xxxxxxxxx>.
Changes v2 => v3:
1. Remove a leftover debug change.
2. Shuffle alloc_new_pack() for cleaner patch.
Changes v1 => v2:
1. Fix case with first program > PAGE_SIZE. (Daniel)
2. Add Fixes tag.
3. Remove a inline to avoid netdev/source_inline error.
---
kernel/bpf/core.c | 70 +++++++++++++++++++++++++++++++----------------
1 file changed, 47 insertions(+), 23 deletions(-)
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index ab630f773ec1..9d0a56aa7c90 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 +825,56 @@ 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 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 size_t select_bpf_prog_pack_size(void)
+{
+ size_t size;
+ void *ptr;
+
+ size = PMD_SIZE * num_online_nodes();
+ ptr = module_alloc(size);
+
+ /* Test whether we can get huge pages. If not just use PAGE_SIZE
+ * packs.
+ */
+ if (!ptr || !is_vm_area_hugepages(ptr))
+ size = PAGE_SIZE;
+
+ vfree(ptr);
+ return size;
+}
+
static struct bpf_prog_pack *alloc_new_pack(void)
{
struct bpf_prog_pack *pack;
- pack = kzalloc(sizeof(*pack) + BITS_TO_BYTES(BPF_PROG_CHUNK_COUNT), GFP_KERNEL);
+ pack = kzalloc(struct_size(pack, bitmap, BITS_TO_LONGS(bpf_prog_chunk_count())),
+ GFP_KERNEL);
if (!pack)
return NULL;
- pack->ptr = module_alloc(BPF_PROG_PACK_SIZE);
+ pack->ptr = module_alloc(bpf_prog_pack_size);
if (!pack->ptr) {
kfree(pack);
return NULL;
}
- bitmap_zero(pack->bitmap, BPF_PROG_PACK_SIZE / BPF_PROG_CHUNK_SIZE);
+ 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 +885,11 @@ static void *bpf_prog_pack_alloc(u32 size)
unsigned long pos;
void *ptr = NULL;
- if (size > BPF_PROG_MAX_PACK_PROG_SIZE) {
+ mutex_lock(&pack_mutex);
+ if (bpf_prog_pack_size == -1)
+ bpf_prog_pack_size = select_bpf_prog_pack_size();
+
+ if (size > bpf_prog_pack_size) {
size = round_up(size, PAGE_SIZE);
ptr = module_alloc(size);
if (ptr) {
@@ -872,13 +897,12 @@ static void *bpf_prog_pack_alloc(u32 size)
set_memory_ro((unsigned long)ptr, size / PAGE_SIZE);
set_memory_x((unsigned long)ptr, size / PAGE_SIZE);
}
- return ptr;
+ goto out;
}
- 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;
}
@@ -904,13 +928,13 @@ 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) {
+ mutex_lock(&pack_mutex);
+ if (hdr->size > bpf_prog_pack_size) {
module_memfree(hdr);
- return;
+ goto out;
}
- pack_ptr = (void *)((unsigned long)hdr & ~(BPF_PROG_PACK_SIZE - 1));
- mutex_lock(&pack_mutex);
+ pack_ptr = (void *)((unsigned long)hdr & ~(bpf_prog_pack_size - 1));
list_for_each_entry(tmp, &pack_list, list) {
if (tmp->ptr == pack_ptr) {
@@ -926,8 +950,8 @@ 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
