linux-kernel - [PATCH 1/3] mm: vmalloc: introduce array allocation functions

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Date:   Tue,  8 Mar 2022 05:59:16 -0500
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Cc:     Michael Ellerman <mpe@...erman.id.au>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Dennis Zhou <dennis@...nel.org>, Tejun Heo <tj@...nel.org>,
        Christoph Lameter <cl@...ux.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>, linux-mm@...ck.org,
        cgroups@...r.kernel.org, stable@...r.kernel.org
Subject: [PATCH 1/3] mm: vmalloc: introduce array allocation functions

Linux has dozens of occurrences of vmalloc(array_size()) and
vzalloc(array_size()).  Allow to simplify the code by providing
vmalloc_array and vcalloc, as well as the underscored variants that let
the caller specify the GFP flags.

Cc: stable@...r.kernel.org
Cc: linux-mm@...ck.org
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 include/linux/vmalloc.h |  5 +++++
 mm/util.c               | 50 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+)

diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 880227b9f044..d1bbd4fd50c5 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -159,6 +159,11 @@ void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
 		int node, const void *caller) __alloc_size(1);
 void *vmalloc_no_huge(unsigned long size) __alloc_size(1);
 
+extern void *__vmalloc_array(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
+extern void *vmalloc_array(size_t n, size_t size) __alloc_size(1, 2);
+extern void *__vcalloc(size_t n, size_t size, gfp_t flags) __alloc_size(1, 2);
+extern void *vcalloc(size_t n, size_t size) __alloc_size(1, 2);
+
 extern void vfree(const void *addr);
 extern void vfree_atomic(const void *addr);
 
diff --git a/mm/util.c b/mm/util.c
index 7e43369064c8..94475abe54a0 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -647,6 +647,56 @@ void *kvrealloc(const void *p, size_t oldsize, size_t newsize, gfp_t flags)
 }
 EXPORT_SYMBOL(kvrealloc);
 
+/**
+ * __vmalloc_array - allocate memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ * @flags: the type of memory to allocate (see kmalloc).
+ */
+void *__vmalloc_array(size_t n, size_t size, gfp_t flags)
+{
+	size_t bytes;
+
+	if (unlikely(check_mul_overflow(n, size, &bytes)))
+		return NULL;
+	return __vmalloc(bytes, flags);
+}
+EXPORT_SYMBOL(__vmalloc_array);
+
+/**
+ * vmalloc_array - allocate memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ */
+void *vmalloc_array(size_t n, size_t size)
+{
+	return __vmalloc_array(n, size, GFP_KERNEL);
+}
+EXPORT_SYMBOL(vmalloc_array);
+
+/**
+ * __vcalloc - allocate and zero memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ * @flags: the type of memory to allocate (see kmalloc).
+ */
+void *__vcalloc(size_t n, size_t size, gfp_t flags)
+{
+	return __vmalloc_array(n, size, flags | __GFP_ZERO);
+}
+EXPORT_SYMBOL(__vcalloc);
+
+/**
+ * vcalloc - allocate and zero memory for a virtually contiguous array.
+ * @n: number of elements.
+ * @size: element size.
+ */
+void *vcalloc(size_t n, size_t size)
+{
+	return __vmalloc_array(n, size, GFP_KERNEL | __GFP_ZERO);
+}
+EXPORT_SYMBOL(vcalloc);
+
 /* Neutral page->mapping pointer to address_space or anon_vma or other */
 void *page_rmapping(struct page *page)
 {
-- 
2.31.1