Re: [RFC blktests fix PATCH] tcp: use GFP_ATOMIC in tcp_disconnect

Chaitanya Kulkarni
2025-11-25T07:28:49Z

On 11/24/25 22:27, Christoph Hellwig wrote:
> I don't think GFP_ATOMIC is right here, you want GFP_NOIO.
>
> And just use the scope API so that you don't have to pass a gfp_t
> several layers down.
>
>
are you saying something like this ?

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 29ad4735fac6..56d0a3777a4d 100644
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -1438,17 +1438,28 @@ static void nvme_tcp_free_queue(struct nvme_ctrl *nctrl, int qid)
struct nvme_tcp_ctrl *ctrl = to_tcp_ctrl(nctrl);
struct nvme_tcp_queue *queue = &ctrl->queues[qid];
unsigned int noreclaim_flag;
+ unsigned int noio_flag;

if (!test_and_clear_bit(NVME_TCP_Q_ALLOCATED, &queue->flags))
return;

page_frag_cache_drain(&queue->pf_cache);

+ /**
+ * Prevent memory reclaim from triggering block I/O during socket
+ * teardown. The socket release path fput -> tcp_close ->
+ * tcp_disconnect -> tcp_send_active_reset may allocate memory, and
+ * allowing reclaim to issue I/O could deadlock if we're being called
+ * from block device teardown (e.g., del_gendisk -> elevator cleanup)
+ * which holds locks that the I/O completion path needs.
+ */
+ noio_flag = memalloc_noio_save();
noreclaim_flag = memalloc_noreclaim_save();
/* ->sock will be released by fput() */
fput(queue->sock->file);
queue->sock = NULL;
memalloc_noreclaim_restore(noreclaim_flag);
+ memalloc_noio_restore(noio_flag);

kfree(queue->pdu);
mutex_destroy(&queue->send_mutex);
--
2.40.0

-ck