leandrof/linux
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

mm: add a signature in struct page

Browse Source 
This is needed by the page_pool to avoid recycling a page not allocated
via page_pool.

The page->signature field is aliased to page->lru.next and
page->compound_head, but it can't be set by mistake because the
signature value is a bad pointer, and can't trigger a false positive
in PageTail() because the last bit is 0.

Co-developed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Matteo Croce <mcroce@microsoft.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Matteo Croce
2021-06-07 21:02:36 +02:00
committed by David S. Miller
parent 35cba15a50
commit c07aea3ef4
4 changed files with 22 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

6
net/core/page_pool.c
View File

@@ -17,6 +17,7 @@
#include <linux/dma-mapping.h>
#include <linux/page-flags.h>
#include <linux/mm.h> /* for __put_page() */
#include <linux/poison.h>
#include <trace/events/page_pool.h>
@@ -221,6 +222,8 @@ static struct page *__page_pool_alloc_page_order(struct page_pool *pool,
return NULL;
}
page->pp_magic |= PP_SIGNATURE;
/* Track how many pages are held 'in-flight' */
pool->pages_state_hold_cnt++;
trace_page_pool_state_hold(pool, page, pool->pages_state_hold_cnt);
@@ -263,6 +266,7 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool,
put_page(page);
continue;
}
page->pp_magic |= PP_SIGNATURE;
pool->alloc.cache[pool->alloc.count++] = page;
/* Track how many pages are held 'in-flight' */
pool->pages_state_hold_cnt++;
@@ -341,6 +345,8 @@ void page_pool_release_page(struct page_pool *pool, struct page *page)
DMA_ATTR_SKIP_CPU_SYNC);
page_pool_set_dma_addr(page, 0);
skip_dma_unmap:
page->pp_magic = 0;
/* This may be the last page returned, releasing the pool, so
* it is not safe to reference pool afterwards.
*/