[PATCH v5 6/6] mm/vmalloc: align vm_area so vmap() can batch mappings

[Wen Jiang <jiangwenxiaomi@gmail.com>]

From: "Barry Song (Xiaomi)" <baohua@kernel.org>

Try to align the vmap virtual address to PMD_SHIFT or a
larger PTE mapping size hinted by the architecture, so
contiguous pages can be batch-mapped when setting PMD or
PTE entries. We do not expect any significant overhead for
this.

Add __get_vm_area_node_aligned_caller() as a wrapper over
__get_vm_area_node() to simplify repeated calls with fixed
arguments.

Signed-off-by: Barry Song (Xiaomi) <baohua@kernel.org>
Signed-off-by: Wen Jiang <jiangwen6@xiaomi.com>
Tested-by: Xueyuan Chen <xueyuan.chen21@gmail.com>
---
 mm/vmalloc.c | 35 ++++++++++++++++++++++++++++++++++-
 1 file changed, 34 insertions(+), 1 deletion(-)

diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index db0492151ad08..2ac805cdf18ad 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3314,6 +3314,14 @@ struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags,
 				  NUMA_NO_NODE, GFP_KERNEL, caller);
 }
 
+static struct vm_struct *__get_vm_area_node_aligned_caller(unsigned long size,
+		unsigned long align, unsigned long flags, const void *caller)
+{
+	return __get_vm_area_node(size, align, PAGE_SHIFT, flags,
+				  VMALLOC_START, VMALLOC_END,
+				  NUMA_NO_NODE, GFP_KERNEL, caller);
+}
+
 /**
  * find_vm_area - find a continuous kernel virtual area
  * @addr:	  base address
@@ -3626,6 +3634,30 @@ static int vmap_pages_range_batched(unsigned long addr, unsigned long end,
 	return err;
 }
 
+static struct vm_struct *vmap_get_aligned_vm_area(unsigned long size,
+		unsigned long flags, pgprot_t prot, const void *caller)
+{
+	struct vm_struct *vm_area;
+	unsigned int shift;
+
+	if (arch_vmap_pmd_supported(prot) && size >= PMD_SIZE) {
+		vm_area = __get_vm_area_node_aligned_caller(size, PMD_SIZE,
+				flags, caller);
+		if (vm_area)
+			return vm_area;
+	}
+
+	shift = arch_vmap_pte_supported_shift(size);
+	if (shift > PAGE_SHIFT) {
+		vm_area = __get_vm_area_node_aligned_caller(size, 1UL << shift,
+				flags, caller);
+		if (vm_area)
+			return vm_area;
+	}
+
+	return __get_vm_area_node_aligned_caller(size, PAGE_SIZE, flags, caller);
+}
+
 /**
  * vmap - map an array of pages into virtually contiguous space
  * @pages: array of page pointers
@@ -3664,7 +3696,8 @@ void *vmap(struct page **pages, unsigned int count,
 		return NULL;
 
 	size = (unsigned long)count << PAGE_SHIFT;
-	area = get_vm_area_caller(size, flags, __builtin_return_address(0));
+	area = vmap_get_aligned_vm_area(size, flags, prot,
+				__builtin_return_address(0));
 	if (!area)
 		return NULL;
 
-- 
2.34.1