[PATCH 4.1 79/86] NVMe: Fix memory leak on retried commands

Greg Kroah-Hartman
2015-11-06T19:32:51Z

From: Keith Busch <keith.busch@intel.com>

commit 0dfc70c33409afc232ef0b9ec210535dfbf9bc61 upstream.

Resources are reallocated for requeued commands, so unmap and release
the iod for the failed command.

It's a pretty bad memory leak and causes a kernel hang if you remove a
drive because of a busy dma pool. You'll get messages spewing like this:

nvme 0000:xx:xx.x: dma_pool_destroy prp list 256, ffff880420dec000 busy

and lock up pci and the driver since removal never completes while
holding a lock.

Signed-off-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@fb.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/block/nvme-core.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

--- a/drivers/block/nvme-core.c
+++ b/drivers/block/nvme-core.c
@@ -590,6 +590,7 @@ static void req_completion(struct nvme_q
struct nvme_iod *iod = ctx;
struct request *req = iod_get_private(iod);
struct nvme_cmd_info *cmd_rq = blk_mq_rq_to_pdu(req);
+ bool requeue = false;

u16 status = le16_to_cpup(&cqe->status) >> 1;

@@ -598,12 +599,13 @@ static void req_completion(struct nvme_q
&& (jiffies - req->start_time) < req->timeout) {
unsigned long flags;

+ requeue = true;
blk_mq_requeue_request(req);
spin_lock_irqsave(req->q->queue_lock, flags);
if (!blk_queue_stopped(req->q))
blk_mq_kick_requeue_list(req->q);
spin_unlock_irqrestore(req->q->queue_lock, flags);
- return;
+ goto release_iod;
}
req->errors = nvme_error_status(status);
} else
@@ -613,7 +615,7 @@ static void req_completion(struct nvme_q
dev_warn(&nvmeq->dev->pci_dev->dev,
"completing aborted command with status:%04x\n",
status);
-
+ release_iod:
if (iod->nents) {
dma_unmap_sg(&nvmeq->dev->pci_dev->dev, iod->sg, iod->nents,
rq_data_dir(req) ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
@@ -626,7 +628,8 @@ static void req_completion(struct nvme_q
}
nvme_free_iod(nvmeq->dev, iod);

- blk_mq_complete_request(req);
+ if (likely(!requeue))
+ blk_mq_complete_request(req);
}

/* length is in bytes. gfp flags indicates whether we may sleep. */