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[68.228.73.187]) by smtp.googlemail.com with ESMTPSA id l16sm4743657otr.13.2019.02.02.11.30.14 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 02 Feb 2019 11:30:15 -0800 (PST) Subject: Re: [PATCH] net: dsa: Fix lockdep false positive splat To: Marc Zyngier , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Andrew Lunn , Vivien Didelot , "David S. Miller" References: <20190202175329.5969-1-marc.zyngier@arm.com> From: Florian Fainelli Openpgp: preference=signencrypt Autocrypt: addr=f.fainelli@gmail.com; prefer-encrypt=mutual; keydata= mQGiBEjPuBIRBACW9MxSJU9fvEOCTnRNqG/13rAGsj+vJqontvoDSNxRgmafP8d3nesnqPyR xGlkaOSDuu09rxuW+69Y2f1TzjFuGpBk4ysWOR85O2Nx8AJ6fYGCoeTbovrNlGT1M9obSFGQ X3IzRnWoqlfudjTO5TKoqkbOgpYqIo5n1QbEjCCwCwCg3DOH/4ug2AUUlcIT9/l3pGvoRJ0E AICDzi3l7pmC5IWn2n1mvP5247urtHFs/uusE827DDj3K8Upn2vYiOFMBhGsxAk6YKV6IP0d ZdWX6fqkJJlu9cSDvWtO1hXeHIfQIE/xcqvlRH783KrihLcsmnBqOiS6rJDO2x1eAgC8meAX SAgsrBhcgGl2Rl5gh/jkeA5ykwbxA/9u1eEuL70Qzt5APJmqVXR+kWvrqdBVPoUNy/tQ8mYc nzJJ63ng3tHhnwHXZOu8hL4nqwlYHRa9eeglXYhBqja4ZvIvCEqSmEukfivk+DlIgVoOAJbh qIWgvr3SIEuR6ayY3f5j0f2ejUMYlYYnKdiHXFlF9uXm1ELrb0YX4GMHz7QnRmxvcmlhbiBG YWluZWxsaSA8Zi5mYWluZWxsaUBnbWFpbC5jb20+iGYEExECACYCGyMGCwkIBwMCBBUCCAME FgIDAQIeAQIXgAUCVF/S8QUJHlwd3wAKCRBhV5kVtWN2DvCVAJ4u4/bPF4P3jxb4qEY8I2gS 6hG0gACffNWlqJ2T4wSSn+3o7CCZNd7SLSC5BA0ESM+4EhAQAL/o09boR9D3Vk1Tt7+gpYr3 WQ6hgYVON905q2ndEoA2J0dQxJNRw3snabHDDzQBAcqOvdi7YidfBVdKi0wxHhSuRBfuOppu pdXkb7zxuPQuSveCLqqZWRQ+Cc2QgF7SBqgznbe6Ngout5qXY5Dcagk9LqFNGhJQzUGHAsIs hap1f0B1PoUyUNeEInV98D8Xd/edM3mhO9nRpUXRK9Bvt4iEZUXGuVtZLT52nK6Wv2EZ1TiT OiqZlf1P+vxYLBx9eKmabPdm3yjalhY8yr1S1vL0gSA/C6W1o/TowdieF1rWN/MYHlkpyj9c Rpc281gAO0AP3V1G00YzBEdYyi0gaJbCEQnq8Vz1vDXFxHzyhgGz7umBsVKmYwZgA8DrrB0M oaP35wuGR3RJcaG30AnJpEDkBYHznI2apxdcuTPOHZyEilIRrBGzDwGtAhldzlBoBwE3Z3MY 31TOpACu1ZpNOMysZ6xiE35pWkwc0KYm4hJA5GFfmWSN6DniimW3pmdDIiw4Ifcx8b3mFrRO BbDIW13E51j9RjbO/nAaK9ndZ5LRO1B/8Fwat7bLzmsCiEXOJY7NNpIEpkoNoEUfCcZwmLrU +eOTPzaF6drw6ayewEi5yzPg3TAT6FV3oBsNg3xlwU0gPK3v6gYPX5w9+ovPZ1/qqNfOrbsE FRuiSVsZQ5s3AAMFD/9XjlnnVDh9GX/r/6hjmr4U9tEsM+VQXaVXqZuHKaSmojOLUCP/YVQo 7IiYaNssCS4FCPe4yrL4FJJfJAsbeyDykMN7wAnBcOkbZ9BPJPNCbqU6dowLOiy8AuTYQ48m vIyQ4Ijnb6GTrtxIUDQeOBNuQC/gyyx3nbL/lVlHbxr4tb6YkhkO6shjXhQh7nQb33FjGO4P WU11Nr9i/qoV8QCo12MQEo244RRA6VMud06y/E449rWZFSTwGqb0FS0seTcYNvxt8PB2izX+ HZA8SL54j479ubxhfuoTu5nXdtFYFj5Lj5x34LKPx7MpgAmj0H7SDhpFWF2FzcC1bjiW9mjW HaKaX23Awt97AqQZXegbfkJwX2Y53ufq8Np3e1542lh3/mpiGSilCsaTahEGrHK+lIusl6mz Joil+u3k01ofvJMK0ZdzGUZ/aPMZ16LofjFA+MNxWrZFrkYmiGdv+LG45zSlZyIvzSiG2lKy kuVag+IijCIom78P9jRtB1q1Q5lwZp2TLAJlz92DmFwBg1hyFzwDADjZ2nrDxKUiybXIgZp9 aU2d++ptEGCVJOfEW4qpWCCLPbOT7XBr+g/4H3qWbs3j/cDDq7LuVYIe+wchy/iXEJaQVeTC y5arMQorqTFWlEOgRA8OP47L9knl9i4xuR0euV6DChDrguup2aJVU4hPBBgRAgAPAhsMBQJU X9LxBQkeXB3fAAoJEGFXmRW1Y3YOj4UAn3nrFLPZekMeqX5aD/aq/dsbXSfyAKC45Go0YyxV HGuUuzv+GKZ6nsysJ7kCDQRXG8fwARAA6q/pqBi5PjHcOAUgk2/2LR5LjjesK50bCaD4JuNc YDhFR7Vs108diBtsho3w8WRd9viOqDrhLJTroVckkk74OY8r+3t1E0Dd4wHWHQZsAeUvOwDM PQMqTUBFuMi6ydzTZpFA2wBR9x6ofl8Ax+zaGBcFrRlQnhsuXLnM1uuvS39+pmzIjasZBP2H UPk5ifigXcpelKmj6iskP3c8QN6x6GjUSmYx+xUfs/GNVSU1XOZn61wgPDbgINJd/THGdqiO iJxCLuTMqlSsmh1+E1dSdfYkCb93R/0ZHvMKWlAx7MnaFgBfsG8FqNtZu3PCLfizyVYYjXbV WO1A23riZKqwrSJAATo5iTS65BuYxrFsFNPrf7TitM8E76BEBZk0OZBvZxMuOs6Z1qI8YKVK UrHVGFq3NbuPWCdRul9SX3VfOunr9Gv0GABnJ0ET+K7nspax0xqq7zgnM71QEaiaH17IFYGS sG34V7Wo3vyQzsk7qLf9Ajno0DhJ+VX43g8+AjxOMNVrGCt9RNXSBVpyv2AMTlWCdJ5KI6V4 KEzWM4HJm7QlNKE6RPoBxJVbSQLPd9St3h7mxLcne4l7NK9eNgNnneT7QZL8fL//s9K8Ns1W t60uQNYvbhKDG7+/yLcmJgjF74XkGvxCmTA1rW2bsUriM533nG9gAOUFQjURkwI8jvMAEQEA AYkCaAQYEQIACQUCVxvH8AIbAgIpCRBhV5kVtWN2DsFdIAQZAQIABgUCVxvH8AAKCRCH0Jac RAcHBIkHD/9nmfog7X2ZXMzL9ktT++7x+W/QBrSTCTmq8PK+69+INN1ZDOrY8uz6htfTLV9+ e2W6G8/7zIvODuHk7r+yQ585XbplgP0V5Xc8iBHdBgXbqnY5zBrcH+Q/oQ2STalEvaGHqNoD UGyLQ/fiKoLZTPMur57Fy1c9rTuKiSdMgnT0FPfWVDfpR2Ds0gpqWePlRuRGOoCln5GnREA/ 2MW2rWf+CO9kbIR+66j8b4RUJqIK3dWn9xbENh/aqxfonGTCZQ2zC4sLd25DQA4w1itPo+f5 V/SQxuhnlQkTOCdJ7b/mby/pNRz1lsLkjnXueLILj7gNjwTabZXYtL16z24qkDTI1x3g98R/ xunb3/fQwR8FY5/zRvXJq5us/nLvIvOmVwZFkwXc+AF+LSIajqQz9XbXeIP/BDjlBNXRZNdo dVuSU51ENcMcilPr2EUnqEAqeczsCGpnvRCLfVQeSZr2L9N4svNhhfPOEscYhhpHTh0VPyxI pPBNKq+byuYPMyk3nj814NKhImK0O4gTyCK9b+gZAVvQcYAXvSouCnTZeJRrNHJFTgTgu6E0 caxTGgc5zzQHeX67eMzrGomG3ZnIxmd1sAbgvJUDaD2GrYlulfwGWwWyTNbWRvMighVdPkSF 6XFgQaosWxkV0OELLy2N485YrTr2Uq64VKyxpncLh50e2RnyAJ9qfUATKC9NgZjRvBztfqy4 a9BQwACgnzGuH1BVeT2J0Ra+ZYgkx7DaPR0= Message-ID: <1235e632-8e06-00c1-7c0c-9effac869838@gmail.com> Date: Sat, 2 Feb 2019 11:30:13 -0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.4.0 MIME-Version: 1.0 In-Reply-To: <20190202175329.5969-1-marc.zyngier@arm.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Le 2/2/19 à 9:53 AM, Marc Zyngier a écrit : > Creating a macvtap on a DSA-backed interface results in the following > splat when lockdep is enabled: > > [ 19.638080] IPv6: ADDRCONF(NETDEV_CHANGE): lan0: link becomes ready > [ 23.041198] device lan0 entered promiscuous mode > [ 23.043445] device eth0 entered promiscuous mode > [ 23.049255] > [ 23.049557] ============================================ > [ 23.055021] WARNING: possible recursive locking detected > [ 23.060490] 5.0.0-rc3-00013-g56c857a1b8d3 #118 Not tainted > [ 23.066132] -------------------------------------------- > [ 23.071598] ip/2861 is trying to acquire lock: > [ 23.076171] 00000000f61990cb (_xmit_ETHER){+...}, at: dev_set_rx_mode+0x1c/0x38 > [ 23.083693] > [ 23.083693] but task is already holding lock: > [ 23.089696] 00000000ecf0c3b4 (_xmit_ETHER){+...}, at: dev_uc_add+0x24/0x70 > [ 23.096774] > [ 23.096774] other info that might help us debug this: > [ 23.103494] Possible unsafe locking scenario: > [ 23.103494] > [ 23.109584] CPU0 > [ 23.112093] ---- > [ 23.114601] lock(_xmit_ETHER); > [ 23.117917] lock(_xmit_ETHER); > [ 23.121233] > [ 23.121233] *** DEADLOCK *** > [ 23.121233] > [ 23.127325] May be due to missing lock nesting notation > [ 23.127325] > [ 23.134315] 2 locks held by ip/2861: > [ 23.137987] #0: 000000003b766c72 (rtnl_mutex){+.+.}, at: rtnetlink_rcv_msg+0x338/0x4e0 > [ 23.146231] #1: 00000000ecf0c3b4 (_xmit_ETHER){+...}, at: dev_uc_add+0x24/0x70 > [ 23.153757] > [ 23.153757] stack backtrace: > [ 23.158243] CPU: 0 PID: 2861 Comm: ip Not tainted 5.0.0-rc3-00013-g56c857a1b8d3 #118 > [ 23.166212] Hardware name: Globalscale Marvell ESPRESSOBin Board (DT) > [ 23.172843] Call trace: > [ 23.175358] dump_backtrace+0x0/0x188 > [ 23.179116] show_stack+0x14/0x20 > [ 23.182524] dump_stack+0xb4/0xec > [ 23.185928] __lock_acquire+0x123c/0x1860 > [ 23.190048] lock_acquire+0xc8/0x248 > [ 23.193724] _raw_spin_lock_bh+0x40/0x58 > [ 23.197755] dev_set_rx_mode+0x1c/0x38 > [ 23.201607] dev_set_promiscuity+0x3c/0x50 > [ 23.205820] dsa_slave_change_rx_flags+0x5c/0x70 > [ 23.210567] __dev_set_promiscuity+0x148/0x1e0 > [ 23.215136] __dev_set_rx_mode+0x74/0x98 > [ 23.219167] dev_uc_add+0x54/0x70 > [ 23.222575] macvlan_open+0x170/0x1d0 > [ 23.226336] __dev_open+0xe0/0x160 > [ 23.229830] __dev_change_flags+0x16c/0x1b8 > [ 23.234132] dev_change_flags+0x20/0x60 > [ 23.238074] do_setlink+0x2d0/0xc50 > [ 23.241658] __rtnl_newlink+0x5f8/0x6e8 > [ 23.245601] rtnl_newlink+0x50/0x78 > [ 23.249184] rtnetlink_rcv_msg+0x360/0x4e0 > [ 23.253397] netlink_rcv_skb+0xe8/0x130 > [ 23.257338] rtnetlink_rcv+0x14/0x20 > [ 23.261012] netlink_unicast+0x190/0x210 > [ 23.265043] netlink_sendmsg+0x288/0x350 > [ 23.269075] sock_sendmsg+0x18/0x30 > [ 23.272659] ___sys_sendmsg+0x29c/0x2c8 > [ 23.276602] __sys_sendmsg+0x60/0xb8 > [ 23.280276] __arm64_sys_sendmsg+0x1c/0x28 > [ 23.284488] el0_svc_common+0xd8/0x138 > [ 23.288340] el0_svc_handler+0x24/0x80 > [ 23.292192] el0_svc+0x8/0xc > > This looks fairly harmless (no actual deadlock occurs), and is > fixed in a similar way to c6894dec8ea9 ("bridge: fix lockdep > addr_list_lock false positive splat") by putting the addr_list_lock > in its own lockdep class. Great timing, I was just looking at this after solving another one seen with the bridge code on net-next. AFAIR you can also trigger this with VLAN and pretty much anything that tries to push UC/MC address list down to the master device. Reviewed-by: Florian Fainelli -- Florian