nvme uses page_frag_cache to preallocate PDU for each preallocated request of block device. Block devices are created in parallel threads, consequently page_frag_cache is used in not thread-safe manner. That leads to incorrect refcounting of backstore pages and premature free.

That can be catched by !sendpage_ok inside network stack:

WARNING: CPU: 7 PID: 467 at ../net/core/skbuff.c:6931 skb_splice_from_iter+0xfa/0x310. tcp_sendmsg_locked+0x782/0xce0 tcp_sendmsg+0x27/0x40 sock_sendmsg+0x8b/0xa0 nvme_tcp_try_send_cmd_pdu+0x149/0x2a0 Then random panic may occur.

Fix that by serializing the usage of page_frag_cache.

Cc: stable@vger.kernel.org # 6.12 Fixes: 4e893ca81170 ("nvme_core: scan namespaces asynchronously") Signed-off-by: Dmitry Bogdanov d.bogdanov@yadro.com --- drivers/nvme/host/tcp.c | 8 ++++++++ 1 file changed, 8 insertions(+)

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c index 1413788ca7d52..823e07759e0d3 100644 --- a/drivers/nvme/host/tcp.c +++ b/drivers/nvme/host/tcp.c @@ -145,6 +145,7 @@ struct nvme_tcp_queue {

struct mutex queue_lock; struct mutex send_mutex; + struct mutex pf_cache_lock; struct llist_head req_list; struct list_head send_list;

@@ -556,9 +557,11 @@ static int nvme_tcp_init_request(struct blk_mq_tag_set *set, struct nvme_tcp_queue *queue = &ctrl->queues[queue_idx]; u8 hdgst = nvme_tcp_hdgst_len(queue);

+ mutex_lock(&queue->pf_cache_lock); req->pdu = page_frag_alloc(&queue->pf_cache, sizeof(struct nvme_tcp_cmd_pdu) + hdgst, GFP_KERNEL | __GFP_ZERO); + mutex_unlock(&queue->pf_cache_lock); if (!req->pdu) return -ENOMEM;

@@ -1420,9 +1423,11 @@ static int nvme_tcp_alloc_async_req(struct nvme_tcp_ctrl *ctrl) struct nvme_tcp_request *async = &ctrl->async_req; u8 hdgst = nvme_tcp_hdgst_len(queue);

+ mutex_lock(&queue->pf_cache_lock); async->pdu = page_frag_alloc(&queue->pf_cache, sizeof(struct nvme_tcp_cmd_pdu) + hdgst, GFP_KERNEL | __GFP_ZERO); + mutex_unlock(&queue->pf_cache_lock); if (!async->pdu) return -ENOMEM;

@@ -1450,6 +1455,7 @@ static void nvme_tcp_free_queue(struct nvme_ctrl *nctrl, int qid) kfree(queue->pdu); mutex_destroy(&queue->send_mutex); mutex_destroy(&queue->queue_lock); + mutex_destroy(&queue->pf_cache_lock); }

static int nvme_tcp_init_connection(struct nvme_tcp_queue *queue) @@ -1772,6 +1778,7 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl, int qid, INIT_LIST_HEAD(&queue->send_list); mutex_init(&queue->send_mutex); INIT_WORK(&queue->io_work, nvme_tcp_io_work); + mutex_init(&queue->pf_cache_lock);

if (qid > 0) queue->cmnd_capsule_len = nctrl->ioccsz * 16; @@ -1903,6 +1910,7 @@ static int nvme_tcp_alloc_queue(struct nvme_ctrl *nctrl, int qid, err_destroy_mutex: mutex_destroy(&queue->send_mutex); mutex_destroy(&queue->queue_lock); + mutex_destroy(&queue->pf_cache_lock); return ret; }