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[24.9.64.241]) by smtp.gmail.com with ESMTPSA id r7sm3500563iop.9.2019.12.06.13.12.09 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 06 Dec 2019 13:12:09 -0800 (PST) Subject: Re: "usbip: Implement SG support to vhci-hcd and stub driver" causes a deadlock To: =?UTF-8?Q?Marek_Marczykowski-G=c3=b3recki?= , Suwan Kim Cc: linux-usb@vger.kernel.org, Valentina Manea , Shuah Khan References: <20191206032406.GE1208@mail-itl> <20191206065058.GA9792@localhost.localdomain> <20191206205742.GP1122@mail-itl> From: Shuah Khan Message-ID: <49f180e4-0e36-1615-0988-31b0199c4e2b@linuxfoundation.org> Date: Fri, 6 Dec 2019 14:12:08 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.1 MIME-Version: 1.0 In-Reply-To: <20191206205742.GP1122@mail-itl> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-usb-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-usb@vger.kernel.org On 12/6/19 1:57 PM, Marek Marczykowski-Górecki wrote: > On Fri, Dec 06, 2019 at 03:50:58PM +0900, Suwan Kim wrote: >> On Fri, Dec 06, 2019 at 04:24:06AM +0100, Marek Marczykowski-Górecki wrote: >>> Hello, >>> >>> I've hit an issue with recent 4.19 and 5.4 kernels. In short: if I >>> connect Yubikey 4 and use its CCID interface (for example `ykman oath >>> list` command), the client side hangs (100% reliably). After 60s I get a >>> message that a CPU hangs waiting for a spinlock (see below). >>> >>> I've bisected it to a ea44d190764b4422af ("usbip: Implement SG support >>> to vhci-hcd and stub driver") commit. Which indeed is also backported to >>> 4.19. >>> >>> Any idea what is going on here? I can easily provide more information, >>> if you tell me how to get it. >>> >> >> Hi, >> >> Thanks for reporting. Could you turn on lockdep and USBIP_DEBUG >> in kernel config and send dmesg log? It will be helpful to figure >> out lock dependency in vhci_hcd. > > Hmm, I've tried, but I don't see much more information there (see > below). I've just enabled PROVE_LOCKING and USBIP_DEBUG. Do I need to do > anything more, like some boot option? > > Also, this one (as the previous one) is from 4.19.84. Interestingly, on > 4.19.87 I don't get the message at all. > > Hmm, I've done also another test: got 4.19.84 with "usbip: Implement SG > support to vhci-hcd and stub driver" reverted and it still hangs... > > I'm going for another bisect round (4.19.81 works, 4.19.84 doesn't). Does 4.19.82 work? thanks, -- Shuah