Re: [PATCH 08/17] prmem: struct page: track vmap_area
From: Matthew Wilcox <willy@infradead.org>
Date: 2018-10-24 03:12:11
Also in:
linux-integrity, linux-mm, lkml
On Wed, Oct 24, 2018 at 12:34:55AM +0300, Igor Stoppa wrote:
The connection between each page and its vmap_area avoids more expensive searches through the btree of vmap_areas.
Typo -- it's an rbtree.
quoted hunk ↗ jump to hunk
+++ b/include/linux/mm_types.h@@ -87,13 +87,24 @@ struct page { /* See page-flags.h for PAGE_MAPPING_FLAGS */ struct address_space *mapping; pgoff_t index; /* Our offset within mapping. */ - /** - * @private: Mapping-private opaque data. - * Usually used for buffer_heads if PagePrivate. - * Used for swp_entry_t if PageSwapCache. - * Indicates order in the buddy system if PageBuddy. - */ - unsigned long private; + union { + /** + * @private: Mapping-private opaque data. + * Usually used for buffer_heads if + * PagePrivate. + * Used for swp_entry_t if PageSwapCache. + * Indicates order in the buddy system if + * PageBuddy. + */ + unsigned long private; + /** + * @area: reference to the containing area + * For pages that are mapped into a virtually + * contiguous area, avoids performing a more + * expensive lookup. + */ + struct vmap_area *area; + };
Not like this. Make it part of a different struct in the existing union, not a part of the pagecache struct. And there's no need to use ->private explicitly.
quoted hunk ↗ jump to hunk
@@ -1747,6 +1750,10 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align, if (!addr) return NULL; + va = __find_vmap_area((unsigned long)addr); + for (i = 0; i < va->vm->nr_pages; i++) + va->vm->pages[i]->area = va;
I don't like it that you're calling this for _every_ vmalloc() caller when most of them will never use this. Perhaps have page->va be initially NULL and then cache the lookup in it when it's accessed for the first time.