bpf: arena: use kmalloc_nolock() in place of kvcalloc()

To make arena_alloc_pages() safe to be called from any context, replace
kvcalloc() with kmalloc_nolock() so as it doesn't sleep or take any
locks.

Signed-off-by: Puranjay Mohan <[email protected]>

Author: puranjaymohan

kernel/bpf/arena.c

@@ -506,8 +506,7 @@ static long arena_alloc_pages(struct bpf_arena *arena, long uaddr, long page_cnt
 			return 0;
 	}
 
-	/* zeroing is needed, since alloc_pages_bulk() only fills in non-zero entries */
-	pages = kvcalloc(page_cnt, sizeof(struct page *), GFP_KERNEL);
+	pages = kmalloc_nolock(page_cnt * sizeof(struct page *), __GFP_ZERO, -1);
 	if (!pages)
 		return 0;
 
@@ -546,12 +545,12 @@ static long arena_alloc_pages(struct bpf_arena *arena, long uaddr, long page_cnt
 			__free_page(pages[i]);
 		goto out;
 	}
-	kvfree(pages);
+	kfree_nolock(pages);
 	return clear_lo32(arena->user_vm_start) + uaddr32;
 out:
 	range_tree_set(&arena->rt, pgoff, page_cnt);
 out_free_pages:
-	kvfree(pages);
+	kfree_nolock(pages);
 	return 0;
 }