block: kmemleak: Track the page allocations for struct request

The pages allocated for struct request contain pointers to other slab
allocations (via ops->init_request). Since kmemleak does not track/scan
page allocations, the slab objects will be reported as leaks (false
positives). This patch adds kmemleak callbacks to allow tracking of such
pages.

Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Bart Van Assche <bart.vanassche@sandisk.com>
Tested-by: Bart Van Assche<bart.vanassche@sandisk.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Jens Axboe <axboe@fb.com>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index f2d67b4047a04d7015c3c2af16871972c3b5a720..2077f0d2f95f8941d466076a29f77c8faa773dbe 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -9,6 +9,7 @@
 #include <linux/backing-dev.h>
 #include <linux/bio.h>
 #include <linux/blkdev.h>
+#include <linux/kmemleak.h>
 #include <linux/mm.h>
 #include <linux/init.h>
 #include <linux/slab.h>
@@ -1438,6 +1439,11 @@ static void blk_mq_free_rq_map(struct blk_mq_tag_set *set,
        while (!list_empty(&tags->page_list)) {
                page = list_first_entry(&tags->page_list, struct page, lru);
                list_del_init(&page->lru);
+               /*
+                * Remove kmemleak object previously allocated in
+                * blk_mq_init_rq_map().
+                */
+               kmemleak_free(page_address(page));
                __free_pages(page, page->private);
        }
 
@@ -1510,6 +1516,11 @@ static struct blk_mq_tags *blk_mq_init_rq_map(struct blk_mq_tag_set *set,
                list_add_tail(&page->lru, &tags->page_list);
 
                p = page_address(page);
+               /*
+                * Allow kmemleak to scan these pages as they contain pointers
+                * to additional allocations like via ops->init_request().
+                */
+               kmemleak_alloc(p, order_to_size(this_order), 1, GFP_KERNEL);
                entries_per_page = order_to_size(this_order) / rq_size;
                to_do = min(entries_per_page, set->queue_depth - i);
                left -= to_do * rq_size;