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authorDaniel Borkmann <daniel@iogearbox.net>2017-01-18 17:14:17 +0300
committerDavid S. Miller <davem@davemloft.net>2017-01-19 01:12:26 +0300
commitd407bd25a204bd66b7346dde24bd3d37ef0e0b05 (patch)
tree01e49e08ca4f4eb258a2e2d9c67d03d503498696 /kernel/bpf/hashtab.c
parent9ed59592e3e379b2e9557dc1d9e9ec8fcbb33f16 (diff)
downloadlinux-d407bd25a204bd66b7346dde24bd3d37ef0e0b05.tar.xz
bpf: don't trigger OOM killer under pressure with map alloc
This patch adds two helpers, bpf_map_area_alloc() and bpf_map_area_free(), that are to be used for map allocations. Using kmalloc() for very large allocations can cause excessive work within the page allocator, so i) fall back earlier to vmalloc() when the attempt is considered costly anyway, and even more importantly ii) don't trigger OOM killer with any of the allocators. Since this is based on a user space request, for example, when creating maps with element pre-allocation, we really want such requests to fail instead of killing other user space processes. Also, don't spam the kernel log with warnings should any of the allocations fail under pressure. Given that, we can make backend selection in bpf_map_area_alloc() generic, and convert all maps over to use this API for spots with potentially large allocation requests. Note, replacing the one kmalloc_array() is fine as overflow checks happen earlier in htab_map_alloc(), since it must also protect the multiplication for vmalloc() should kmalloc_array() fail. Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Acked-by: Alexei Starovoitov <ast@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/bpf/hashtab.c')
-rw-r--r--kernel/bpf/hashtab.c22
1 files changed, 9 insertions, 13 deletions
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 3f2bb58952d8..a753bbe7df0a 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -13,7 +13,6 @@
#include <linux/bpf.h>
#include <linux/jhash.h>
#include <linux/filter.h>
-#include <linux/vmalloc.h>
#include "percpu_freelist.h"
#include "bpf_lru_list.h"
@@ -103,7 +102,7 @@ static void htab_free_elems(struct bpf_htab *htab)
free_percpu(pptr);
}
free_elems:
- vfree(htab->elems);
+ bpf_map_area_free(htab->elems);
}
static struct htab_elem *prealloc_lru_pop(struct bpf_htab *htab, void *key,
@@ -125,7 +124,8 @@ static int prealloc_init(struct bpf_htab *htab)
{
int err = -ENOMEM, i;
- htab->elems = vzalloc(htab->elem_size * htab->map.max_entries);
+ htab->elems = bpf_map_area_alloc(htab->elem_size *
+ htab->map.max_entries);
if (!htab->elems)
return -ENOMEM;
@@ -320,14 +320,10 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
goto free_htab;
err = -ENOMEM;
- htab->buckets = kmalloc_array(htab->n_buckets, sizeof(struct bucket),
- GFP_USER | __GFP_NOWARN);
-
- if (!htab->buckets) {
- htab->buckets = vmalloc(htab->n_buckets * sizeof(struct bucket));
- if (!htab->buckets)
- goto free_htab;
- }
+ htab->buckets = bpf_map_area_alloc(htab->n_buckets *
+ sizeof(struct bucket));
+ if (!htab->buckets)
+ goto free_htab;
for (i = 0; i < htab->n_buckets; i++) {
INIT_HLIST_HEAD(&htab->buckets[i].head);
@@ -354,7 +350,7 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
free_extra_elems:
free_percpu(htab->extra_elems);
free_buckets:
- kvfree(htab->buckets);
+ bpf_map_area_free(htab->buckets);
free_htab:
kfree(htab);
return ERR_PTR(err);
@@ -1014,7 +1010,7 @@ static void htab_map_free(struct bpf_map *map)
prealloc_destroy(htab);
free_percpu(htab->extra_elems);
- kvfree(htab->buckets);
+ bpf_map_area_free(htab->buckets);
kfree(htab);
}