Re: FAILED: Patch "io_uring/zcrx: fix post open error handling" failed to apply to 6.18-stable tree

[Pavel Begunkov <asml.silence@gmail.com>]

On 3/1/26 13:22, Jens Axboe wrote:
> On 2/28/26 6:17 PM, Sasha Levin wrote:
>> The patch below does not apply to the 6.18-stable tree.
>> If someone wants it applied there, or to any other stable or longterm
>> tree, then please email the backport, including the original git commit
>> id to <stable@vger.kernel.org>.
> 
> Looks like this has dependencies on parts of this:
> 
> https://lore.kernel.org/io-uring/cover.1763029704.git.asml.silence@gmail.com/
> 
> series. But seems easier to just do a variant for the 6.18 base,
> I'll leave that to Pavel.

I was thinking to remove post open error handling. xarray is preallocated
and shouldn't fail. And copy_to_user can be moved earlier. Should be safer
than taking all deps.

diff --git a/io_uring/zcrx.c b/io_uring/zcrx.c
index c524be7109c2..c6ac7365acae 100644
--- a/io_uring/zcrx.c
+++ b/io_uring/zcrx.c
@@ -625,6 +625,14 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
  	if (ret)
  		goto netdev_put_unlock;
  
+	reg.zcrx_id = id;
+	if (copy_to_user(arg, &reg, sizeof(reg)) ||
+	    copy_to_user(u64_to_user_ptr(reg.region_ptr), &rd, sizeof(rd)) ||
+	    copy_to_user(u64_to_user_ptr(reg.area_ptr), &area, sizeof(area))) {
+		ret = -EFAULT;
+		goto err;
+	}
+
  	mp_param.mp_ops = &io_uring_pp_zc_ops;
  	mp_param.mp_priv = ifq;
  	ret = __net_mp_open_rxq(ifq->netdev, reg.if_rxq, &mp_param, NULL);
@@ -633,21 +641,11 @@ int io_register_zcrx_ifq(struct io_ring_ctx *ctx,
  	netdev_unlock(ifq->netdev);
  	ifq->if_rxq = reg.if_rxq;
  
-	reg.zcrx_id = id;
-
  	scoped_guard(mutex, &ctx->mmap_lock) {
  		/* publish ifq */
-		ret = -ENOMEM;
-		if (xa_store(&ctx->zcrx_ctxs, id, ifq, GFP_KERNEL))
-			goto err;
+		xa_store(&ctx->zcrx_ctxs, id, ifq, GFP_KERNEL);
  	}
  
-	if (copy_to_user(arg, &reg, sizeof(reg)) ||
-	    copy_to_user(u64_to_user_ptr(reg.region_ptr), &rd, sizeof(rd)) ||
-	    copy_to_user(u64_to_user_ptr(reg.area_ptr), &area, sizeof(area))) {
-		ret = -EFAULT;
-		goto err;
-	}
  	return 0;
  netdev_put_unlock:
  	netdev_put(ifq->netdev, &ifq->netdev_tracker);

  
-- 
Pavel Begunkov