On Mon, Mar 27, 2017 at 10:43:59AM -0700, Omar Sandoval wrote: > From: Omar Sandoval <[email protected]> > > CONFIG_DEBUG_TEST_DRIVER_REMOVE found a possible leak of q->rq_wb in a > couple of cases: when a request queue is reregistered and when gendisks > share a request_queue. This has been a problem since wbt was introduced, > but the WARN_ON(!list_empty(&stats->callbacks)) in the blk-stat rework > exposed it. The fix is unfortunately a hack until we fix all of the > drivers sharing a request_queue. > > Fixes: 87760e5eef35 ("block: hook up writeback throttling") > Signed-off-by: Omar Sandoval <[email protected]> > --- > block/blk-sysfs.c | 16 +++++++++++++++- > 1 file changed, 15 insertions(+), 1 deletion(-) > > diff --git a/block/blk-sysfs.c b/block/blk-sysfs.c > index fa831cb2fc30..a187e3f70028 100644 > --- a/block/blk-sysfs.c > +++ b/block/blk-sysfs.c > @@ -893,7 +893,21 @@ int blk_register_queue(struct gendisk *disk) > > kobject_uevent(&q->kobj, KOBJ_ADD); > > - blk_wb_init(q); > + /* > + * There are two cases where wbt may have already been initialized: > + * 1. A call sequence of blk_register_queue(); blk_unregister_queue(); > + * blk_register_queue(). > + * 2. Multiple gendisks sharing a request_queue. > + * > + * To fix case 1, we'd like to call wbt_exit() in > + * blk_unregister_queue(). However, that's unsafe for case 2. So, we're > + * forced to do this and call wbt_exit() in blk_release_queue() instead. > + * > + * Note that in case 2, wbt will account across disks until those legacy > + * drivers are fixed. > + */ > + if (!q->rq_wb) > + blk_wb_init(q);
Since 'rq_wb' is per-queue and its life time is same with queue's, I am wondering why blk_wb_init() isn't put into blk_alloc_queue_node() or queue's initialization api(blk_init_allocated_queue(), or blk_mq_init_allocated_queue())? Thanks, Ming
