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

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>

kernel/bpf/arraymap.c

@@ -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);
 	}

kernel/bpf/devmap.c

@@ -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;
 

kernel/bpf/hashtab.c

@@ -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)

mm/percpu.c

@@ -1329,18 +1329,21 @@ 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.
  */
 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 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
 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 @@ static void __percpu *pcpu_alloc(size_t size, size_t align, bool reserved,
  *
  * 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.