[PATCH 2/9] mm: blk-mq: uses page->list incorrectly

[Dave Hansen <dave@sr71.net>]

From: Dave Hansen <dave.hansen@linux.intel.com>

'struct page' has two list_head fields: 'lru' and 'list'.
Conveniently, they are unioned together.  This means that code
can use them interchangably, which gets horribly confusing.

The blk-mq made the logical decision to try to use page->list.
But, that field was actually introduced just for the slub code.
->lru is the right field to use outside of slab/slub.

Signed-off-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
---

 linux.git-davehans/block/blk-mq.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff -puN block/blk-mq.c~blk-mq-uses-page-list-incorrectly block/blk-mq.c
--- linux.git/block/blk-mq.c~blk-mq-uses-page-list-incorrectly	2014-01-02 13:40:29.388270304 -0800
+++ linux.git-davehans/block/blk-mq.c	2014-01-02 13:40:29.392270484 -0800
@@ -1091,8 +1091,8 @@ static void blk_mq_free_rq_map(struct bl
 	struct page *page;
 
 	while (!list_empty(&hctx->page_list)) {
-		page = list_first_entry(&hctx->page_list, struct page, list);
-		list_del_init(&page->list);
+		page = list_first_entry(&hctx->page_list, struct page, lru);
+		list_del_init(&page->lru);
 		__free_pages(page, page->private);
 	}
 
@@ -1156,7 +1156,7 @@ static int blk_mq_init_rq_map(struct blk
 			break;
 
 		page->private = this_order;
-		list_add_tail(&page->list, &hctx->page_list);
+		list_add_tail(&page->lru, &hctx->page_list);
 
 		p = page_address(page);
 		entries_per_page = order_to_size(this_order) / rq_size;
_

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