When a page is used for virtual memory, it is often necessary to obtain
a handler to the corresponding vm_struct, which refers to the virtually
continuous area generated when invoking vmalloc.
The struct page has a "mapping" field, which can be re-used, to store a
pointer to the parent area.
This will avoid more expensive searches, later on.
Signed-off-by: Igor Stoppa <igor.stoppa@xxxxxxxxxx>
---
include/linux/mm_types.h | 1 +
mm/vmalloc.c | 5 +++++
2 files changed, 6 insertions(+)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index fd1af6b9591d..c3a4825e10c0 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -84,6 +84,7 @@ struct page {
void *s_mem; /* slab first object */
atomic_t compound_mapcount; /* first tail page */
/* page_deferred_list().next -- second tail page */
+ struct vm_struct *area;
};
/* Second double word */
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index 673942094328..14d99ed22397 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -1536,6 +1536,7 @@ static void __vunmap(const void *addr, int deallocate_pages)
struct page *page = area->pages[i];
BUG_ON(!page);
+ page->area = NULL;
__free_pages(page, 0);
}
@@ -1744,6 +1745,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
const void *caller)
{
struct vm_struct *area;
+ unsigned int i;
void *addr;
unsigned long real_size = size;
@@ -1769,6 +1771,9 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
kmemleak_vmalloc(area, size, gfp_mask);
+ for (i = 0; i < area->nr_pages; i++)
+ area->pages[i]->area = area;
+
return addr;
fail:
--
2.14.1
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