From: Jens Axboe Date: Mon, 27 Jun 2005 12:49:39 +0000 (+0200) Subject: [PATCH] CFQ io scheduler: scheduler switch oops X-Git-Tag: v2.6.13-rc1~51^2~45 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=96c51ce94e8415d2dfb08358bbd50e1589111f33;p=linux-2.6 [PATCH] CFQ io scheduler: scheduler switch oops If cfq is managing a queue and a new scheduler is later selected, it is possible for the cfqd unplug_work work to be queued after the kblockd work struct has been flushed. The problem is the ordering of cfq_shutdown_timer_wq() and blk_put_queue() in cfq_put_cfqd(). The latter may rearm the work, leaving cfq_kick_queue() with dead data. Signed-off-by: Jens Axboe Signed-off-by: Linus Torvalds --- diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c index 1ecb179b86..ff1cc968f9 100644 --- a/drivers/block/cfq-iosched.c +++ b/drivers/block/cfq-iosched.c @@ -2249,10 +2249,11 @@ static void cfq_put_cfqd(struct cfq_data *cfqd) if (!atomic_dec_and_test(&cfqd->ref)) return; - cfq_shutdown_timer_wq(cfqd); - blk_put_queue(q); + cfq_shutdown_timer_wq(cfqd); + q->elevator->elevator_data = NULL; + mempool_destroy(cfqd->crq_pool); kfree(cfqd->crq_hash); kfree(cfqd->cfq_hash);