[PATCH] cfq: bad allocation

Arjan (sensibly) put a might_sleep() in mempool_alloc() and it caught a bad
cfq usage.

Signed-off-by: Jens Axboe <axboe@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

diff --git a/drivers/block/cfq-iosched.c b/drivers/block/cfq-iosched.c
index c32652db8593e2505f42b4aae783ab9ccf62b8b7..fc5f519ed892644c1f34e101cb0a023f2986903b 100644 (file)
--- a/drivers/block/cfq-iosched.c
+++ b/drivers/block/cfq-iosched.c
@@ -456,37 +456,61 @@ static void cfq_put_queue(struct cfq_data *cfqd, struct cfq_queue *cfqq)
        mempool_free(cfqq, cfq_mpool);
 }
 
-static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, int pid)
+static struct cfq_queue *__cfq_get_queue(struct cfq_data *cfqd, int pid,
+                                        int gfp_mask)
 {
        const int hashval = hash_long(current->tgid, CFQ_QHASH_SHIFT);
        struct cfq_queue *cfqq = __cfq_find_cfq_hash(cfqd, pid, hashval);
 
        if (!cfqq) {
-               cfqq = mempool_alloc(cfq_mpool, GFP_NOIO);
+               cfqq = mempool_alloc(cfq_mpool, gfp_mask);
 
-               INIT_LIST_HEAD(&cfqq->cfq_hash);
-               INIT_LIST_HEAD(&cfqq->cfq_list);
-               RB_CLEAR_ROOT(&cfqq->sort_list);
+               if (cfqq) {
+                       INIT_LIST_HEAD(&cfqq->cfq_hash);
+                       INIT_LIST_HEAD(&cfqq->cfq_list);
+                       RB_CLEAR_ROOT(&cfqq->sort_list);
 
-               cfqq->pid = pid;
-               cfqq->queued[0] = cfqq->queued[1] = 0;
-               list_add(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
+                       cfqq->pid = pid;
+                       cfqq->queued[0] = cfqq->queued[1] = 0;
+                       list_add(&cfqq->cfq_hash, &cfqd->cfq_hash[hashval]);
+               }
        }
 
        return cfqq;
 }
 
-static void cfq_enqueue(struct cfq_data *cfqd, struct cfq_rq *crq)
+static struct cfq_queue *cfq_get_queue(struct cfq_data *cfqd, int pid,
+                                      int gfp_mask)
 {
+       request_queue_t *q = cfqd->queue;
        struct cfq_queue *cfqq;
 
-       cfqq = cfq_get_queue(cfqd, current->tgid);
+       spin_lock_irq(q->queue_lock);
+       cfqq = __cfq_get_queue(cfqd, pid, gfp_mask);
+       spin_unlock_irq(q->queue_lock);
+
+       return cfqq;
+}
 
-       cfq_add_crq_rb(cfqd, cfqq, crq);
+static void cfq_enqueue(struct cfq_data *cfqd, struct cfq_rq *crq)
+{
+       struct cfq_queue *cfqq;
 
-       if (list_empty(&cfqq->cfq_list)) {
-               list_add(&cfqq->cfq_list, &cfqd->rr_list);
-               cfqd->busy_queues++;
+       cfqq = __cfq_get_queue(cfqd, current->tgid, GFP_ATOMIC);
+       if (cfqq) {
+               cfq_add_crq_rb(cfqd, cfqq, crq);
+
+               if (list_empty(&cfqq->cfq_list)) {
+                       list_add(&cfqq->cfq_list, &cfqd->rr_list);
+                       cfqd->busy_queues++;
+               }
+       } else {
+               /*
+                * should can only happen if the request wasn't allocated
+                * through blk_alloc_request(), eg stack requests from ide-cd
+                * (those should be removed) _and_ we are in OOM.
+                */
+               list_add_tail(&crq->request->queuelist, cfqd->dispatch);
        }
 }
 
@@ -617,8 +641,17 @@ static void cfq_put_request(request_queue_t *q, struct request *rq)
 static int cfq_set_request(request_queue_t *q, struct request *rq, int gfp_mask)
 {
        struct cfq_data *cfqd = q->elevator.elevator_data;
-       struct cfq_rq *crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
+       struct cfq_queue *cfqq;
+       struct cfq_rq *crq;
+
+       /*
+        * prepare a queue up front, so cfq_enqueue() doesn't have to
+        */
+       cfqq = cfq_get_queue(cfqd, current->tgid, gfp_mask);
+       if (!cfqq)
+               return 1;
 
+       crq = mempool_alloc(cfqd->crq_pool, gfp_mask);
        if (crq) {
                RB_CLEAR(&crq->rb_node);
                crq->request = rq;