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[142.162.112.119]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-508f66ce03esm18225341cf.27.2026.03.06.15.10.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 06 Mar 2026 15:10:25 -0800 (PST) Received: from jgg by wakko with local (Exim 4.97) (envelope-from ) id 1vyeJM-0000000FcSI-0t9y; Fri, 06 Mar 2026 19:10:24 -0400 Date: Fri, 6 Mar 2026 19:10:24 -0400 From: Jason Gunthorpe To: Praveen Kannoju Cc: "saeedm@nvidia.com" , "leon@kernel.org" , "tariqt@nvidia.com" , "mbloch@nvidia.com" , "andrew+netdev@lunn.ch" , "davem@davemloft.net" , "edumazet@google.com" , "kuba@kernel.org" , "pabeni@redhat.com" , "netdev@vger.kernel.org" , "linux-rdma@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Rama Nichanamatlu , Manjunath Patil , Anand Khoje Subject: Re: [PATCH] net/mlx5: poll mlx5 eq during irq migration Message-ID: <20260306231024.GF1687929@ziepe.ca> References: <20260304161704.910564-1-praveen.kannoju@oracle.com> <20260304201151.GI964116@ziepe.ca> <20260306003217.GB1687929@ziepe.ca> Precedence: bulk X-Mailing-List: linux-rdma@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Fri, Mar 06, 2026 at 02:19:09PM +0000, Praveen Kannoju wrote: > > > On Thu, Mar 05, 2026 at 05:08:52PM +0000, Praveen Kannoju wrote: > > > > > Regardless of the underlying causes, which may include IRQ loss > > > or EQ re-arming failure, the TX queue becomes stuck, and the > > > timeout handler is only triggered once the queue is declared > > > full. In scenarios where only specialized packets, such as > > > heartbeat packets, are sent through the queue, it takes > > > significantly longer for the queue to fill and be identified as > > > stuck. A proven solution for this issue is polling the EQ > > > immediately after the corresponding IRQ migration, which allows > > > for earlier recovery and prevents the transmission queue from > > > becoming stuck. > > > > I undersand all of this, but for upstreaming we want the root cause, not > > bodges like this. > > > > There is no reason to do what this patch does, the IRQ system is not supposed > > to loose interrupts on migration, if that is happening on your systems it is a > > serious bug that must be root caused. > > Thank you, Jason. > We'll evaluate more on it. If this is in a VM running under qemu - qemu does Lots Of Stuff whenever a MSI-X is changed and that stuff has been buggy before and resulted in lost things. If it is bare metal, I'm shocked. Maybe an IOMMU driver bug in the interrupt remapping? Jason