The area->pages stores the struct pages allocated for vmalloc mappings.
The allocated memory can be hugepage if arch has HAVE_ARCH_HUGE_VMALLOC
set, while area->pages itself does not have to be hugepage backed.
Suppose that we want to vmalloc 1026M of memory, then area->pages is
2052K in size, which is large than PMD_SIZE when the pagesize is 4K.
Currently, 4096K will be allocated for area->pages, wherein 2044K is
wasted.
This introduces __vmalloc_node_no_huge, and makes area->pages backed by
small pages, because I think to allocate hugepage for area->pages is
unnecessary and vulnerable to abuse.
Signed-off-by: Xu Yu <xuyu@xxxxxxxxxxxxxxxxx>
---
include/linux/vmalloc.h | 2 ++
mm/vmalloc.c | 15 ++++++++++++---
2 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h
index 6e022cc712e6..e93f39eb46a5 100644
--- a/include/linux/vmalloc.h
+++ b/include/linux/vmalloc.h
@@ -150,6 +150,8 @@ extern void *__vmalloc_node_range(unsigned long size, unsigned long align,
const void *caller) __alloc_size(1);
void *__vmalloc_node(unsigned long size, unsigned long align, gfp_t gfp_mask,
int node, const void *caller) __alloc_size(1);
+void *__vmalloc_node_no_huge(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 vfree(const void *addr);
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index d2a00ad4e1dd..0bdbb96d3e3f 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -2925,17 +2925,18 @@ static void *__vmalloc_area_node(struct vm_struct *area, gfp_t gfp_mask,
unsigned long size = get_vm_area_size(area);
unsigned long array_size;
unsigned int nr_small_pages = size >> PAGE_SHIFT;
+ unsigned int max_small_pages = ALIGN(size, 1UL << page_shift) >> PAGE_SHIFT;
unsigned int page_order;
- array_size = (unsigned long)nr_small_pages * sizeof(struct page *);
+ array_size = (unsigned long)max_small_pages * sizeof(struct page *);
gfp_mask |= __GFP_NOWARN;
if (!(gfp_mask & (GFP_DMA | GFP_DMA32)))
gfp_mask |= __GFP_HIGHMEM;
/* Please note that the recursion is strictly bounded. */
if (array_size > PAGE_SIZE) {
- area->pages = __vmalloc_node(array_size, 1, nested_gfp, node,
- area->caller);
+ area->pages = __vmalloc_node_no_huge(array_size, 1, nested_gfp,
+ node, area->caller);
} else {
area->pages = kmalloc_node(array_size, nested_gfp, node);
}
@@ -3114,6 +3115,14 @@ void *__vmalloc_node(unsigned long size, unsigned long align,
return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
gfp_mask, PAGE_KERNEL, 0, node, caller);
}
+
+void *__vmalloc_node_no_huge(unsigned long size, unsigned long align,
+ gfp_t gfp_mask, int node, const void *caller)
+{
+ return __vmalloc_node_range(size, align, VMALLOC_START, VMALLOC_END,
+ gfp_mask, PAGE_KERNEL, VM_NO_HUGE_VMAP, node, caller);
+}
+
/*
* This is only for performance analysis of vmalloc and stress purpose.
* It is required by vmalloc test module, therefore do not use it other
--
2.20.1.2432.ga663e714
