Messages in this thread Patch in this message |  | | From | Igor Stoppa <> | Subject | [PATCH 3/6] struct page: add field for vm_struct | Date | Sun, 4 Feb 2018 18:47:29 +0200 |
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When a page is used for virtual memory, it is often necessary to obtian 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.
As example, the function find_vm_area is reimplemented, to take advantage of the newly introduced field.
Signed-off-by: Igor Stoppa <igor.stoppa@huawei.com> --- include/linux/mm_types.h | 1 + mm/vmalloc.c | 18 +++++++++++++----- 2 files changed, 14 insertions(+), 5 deletions(-)
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index cfd0ac4e5e0e..2abd540b969f 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -56,6 +56,7 @@ 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..44c5dfcb2fd7 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -1466,13 +1466,16 @@ struct vm_struct *get_vm_area_caller(unsigned long size, unsigned long flags, */ struct vm_struct *find_vm_area(const void *addr) { - struct vmap_area *va; + struct page *page; - va = find_vmap_area((unsigned long)addr); - if (va && va->flags & VM_VM_AREA) - return va->vm; + if (unlikely(!is_vmalloc_addr(addr))) + return NULL; - return NULL; + page = vmalloc_to_page(addr); + if (unlikely(!page)) + return NULL; + + return page->area; } /** @@ -1536,6 +1539,7 @@ 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 +1748,7 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, const void *caller) { struct vm_struct *area; + unsigned int page_counter; void *addr; unsigned long real_size = size; @@ -1769,6 +1774,9 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, kmemleak_vmalloc(area, size, gfp_mask); + for (page_counter = 0; page_counter < area->nr_pages; page_counter++) + area->pages[page_counter]->area = area; + return addr; fail: -- 2.16.0
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