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Merge branch 'bpf-Fix-for-BPF-devmap-percpu-allocation-splat'

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Daniel Borkmann says:

====================
bpf: Fix for BPF devmap percpu allocation splat

The set fixes a splat in devmap percpu allocation when we alloc
the flush bitmap. Patch 1 is a prerequisite for the fix in patch 2,
patch 1 is rather small, so if this could be routed via -net, for
example, with Tejun's Ack that would be good. Patch 3 gets rid of
remaining PCPU_MIN_UNIT_SIZE checks, which are percpu allocator
internals and should not be used.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller 2017-10-19 13:14:03 +01:00
commit 4bbb508348
4 changed files with 14 additions and 12 deletions
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2
kernel/bpf/arraymap.c
View file

@ -98,7 +98,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
array_size += (u64) attr->max_entries * elem_size * num_possible_cpus();
if (array_size >= U32_MAX - PAGE_SIZE ||
elem_size > PCPU_MIN_UNIT_SIZE || bpf_array_alloc_percpu(array)) {
bpf_array_alloc_percpu(array)) {
bpf_map_area_free(array);
return ERR_PTR(-ENOMEM);
}

5
kernel/bpf/devmap.c
View file

@ -111,8 +111,9 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
err = -ENOMEM;
/* A per cpu bitfield with a bit per possible net device */
dtab->flush_needed = __alloc_percpu(dev_map_bitmap_size(attr),
__alignof__(unsigned long));
dtab->flush_needed = __alloc_percpu_gfp(dev_map_bitmap_size(attr),
__alignof__(unsigned long),
GFP_KERNEL | __GFP_NOWARN);
if (!dtab->flush_needed)
goto free_dtab;

4
kernel/bpf/hashtab.c
View file

@ -317,10 +317,6 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
*/
goto free_htab;
if (percpu && round_up(htab->map.value_size, 8) > PCPU_MIN_UNIT_SIZE)
/* make sure the size for pcpu_alloc() is reasonable */
goto free_htab;
htab->elem_size = sizeof(struct htab_elem) +
round_up(htab->map.key_size, 8);
if (percpu)

15
mm/percpu.c
View file

@ -1329,7 +1329,9 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
* @gfp: allocation flags
*
* Allocate percpu area of @size bytes aligned at @align. If @gfp doesn't
* contain %GFP_KERNEL, the allocation is atomic.
* contain %GFP_KERNEL, the allocation is atomic. If @gfp has __GFP_NOWARN
* then no warning will be triggered on invalid or failed allocation
* requests.
*
* RETURNS:
* Percpu pointer to the allocated area on success, NULL on failure.
@ -1337,10 +1339,11 @@ static struct pcpu_chunk *pcpu_chunk_addr_search(void *addr)
static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
gfp_t gfp)
{
bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
bool do_warn = !(gfp & __GFP_NOWARN);
static int warn_limit = 10;
struct pcpu_chunk *chunk;
const char *err;
bool is_atomic = (gfp & GFP_KERNEL) != GFP_KERNEL;
int slot, off, cpu, ret;
unsigned long flags;
void __percpu *ptr;
@ -1361,7 +1364,7 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
if (unlikely(!size || size > PCPU_MIN_UNIT_SIZE || align > PAGE_SIZE ||
!is_power_of_2(align))) {
WARN(true, "illegal size (%zu) or align (%zu) for percpu allocation\n",
WARN(do_warn, "illegal size (%zu) or align (%zu) for percpu allocation\n",
size, align);
return NULL;
}
@ -1482,7 +1485,7 @@ fail_unlock:
fail:
trace_percpu_alloc_percpu_fail(reserved, is_atomic, size, align);
if (!is_atomic && warn_limit) {
if (!is_atomic && do_warn && warn_limit) {
pr_warn("allocation failed, size=%zu align=%zu atomic=%d, %s\n",
size, align, is_atomic, err);
dump_stack();
@ -1507,7 +1510,9 @@ fail:
*
* Allocate zero-filled percpu area of @size bytes aligned at @align. If
* @gfp doesn't contain %GFP_KERNEL, the allocation doesn't block and can
* be called from any context but is a lot more likely to fail.
* be called from any context but is a lot more likely to fail. If @gfp
* has __GFP_NOWARN then no warning will be triggered on invalid or failed
* allocation requests.
*
* RETURNS:
* Percpu pointer to the allocated area on success, NULL on failure.