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Wed, 3 Jun 2020 11:31:11 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=web.de; s=dbaedf251592; t=1591198217; bh=Rn7fKHsFwwLiEDgA/knExuHS54ZAZVO02QRZ6k3ZyQw=; h=X-UI-Sender-Class:To:Cc:Subject:From:Date; b=fdFjp91yBSfmCCQuEF3025+1+9nOx16qTgwCi3Ifl7dPsxhZs1koYRPU1X9s+9nL3 bgu4zy6rJll3L8404giD2f8ybctXT5vpn6Q/4AamdnCun8KcT71St6E1/wEd5Sitz+ JwL0gJt9eoe5mGoxzFQmSxMJFn6/83DHGH6bAqCU= X-UI-Sender-Class: c548c8c5-30a9-4db5-a2e7-cb6cb037b8f9 Received: from [192.168.1.2] ([93.131.82.231]) by smtp.web.de (mrweb006 [213.165.67.108]) with ESMTPSA (Nemesis) id 1MlLA1-1jGqJA08VB-00lmFU; Wed, 03 Jun 2020 17:30:17 +0200 To: Cheng Jian , kernel-janitors@vger.kernel.org Cc: Wang ShaoBo , Chen Wandun , Li Bin , Petr Mladek , Steven Rostedt , Sergey Senozhatsky , Xie XiuQi , linux-kernel@vger.kernel.org Subject: Re: [PATCH RFC] panic: Fix deadlock in panic() From: Markus Elfring Autocrypt: addr=Markus.Elfring@web.de; prefer-encrypt=mutual; keydata= mQINBFg2+xABEADBJW2hoUoFXVFWTeKbqqif8VjszdMkriilx90WB5c0ddWQX14h6w5bT/A8 +v43YoGpDNyhgA0w9CEhuwfZrE91GocMtjLO67TAc2i2nxMc/FJRDI0OemO4VJ9RwID6ltwt mpVJgXGKkNJ1ey+QOXouzlErVvE2fRh+KXXN1Q7fSmTJlAW9XJYHS3BDHb0uRpymRSX3O+E2 lA87C7R8qAigPDZi6Z7UmwIA83ZMKXQ5stA0lhPyYgQcM7fh7V4ZYhnR0I5/qkUoxKpqaYLp YHBczVP+Zx/zHOM0KQphOMbU7X3c1pmMruoe6ti9uZzqZSLsF+NKXFEPBS665tQr66HJvZvY GMDlntZFAZ6xQvCC1r3MGoxEC1tuEa24vPCC9RZ9wk2sY5Csbva0WwYv3WKRZZBv8eIhGMxs rcpeGShRFyZ/0BYO53wZAPV1pEhGLLxd8eLN/nEWjJE0ejakPC1H/mt5F+yQBJAzz9JzbToU 5jKLu0SugNI18MspJut8AiA1M44CIWrNHXvWsQ+nnBKHDHHYZu7MoXlOmB32ndsfPthR3GSv jN7YD4Ad724H8fhRijmC1+RpuSce7w2JLj5cYj4MlccmNb8YUxsE8brY2WkXQYS8Ivse39MX BE66MQN0r5DQ6oqgoJ4gHIVBUv/ZwgcmUNS5gQkNCFA0dWXznQARAQABtCZNYXJrdXMgRWxm cmluZyA8TWFya3VzLkVsZnJpbmdAd2ViLmRlPokCVAQTAQgAPhYhBHDP0hzibeXjwQ/ITuU9 Figxg9azBQJYNvsQAhsjBQkJZgGABQsJCAcCBhUICQoLAgQWAgMBAh4BAheAAAoJEOU9Figx g9azcyMP/iVihZkZ4VyH3/wlV3nRiXvSreqg+pGPI3c8J6DjP9zvz7QHN35zWM++1yNek7Ar OVXwuKBo18ASlYzZPTFJZwQQdkZSV+atwIzG3US50ZZ4p7VyUuDuQQVVqFlaf6qZOkwHSnk+ CeGxlDz1POSHY17VbJG2CzPuqMfgBtqIU1dODFLpFq4oIAwEOG6fxRa59qbsTLXxyw+PzRaR LIjVOit28raM83Efk07JKow8URb4u1n7k9RGAcnsM5/WMLRbDYjWTx0lJ2WO9zYwPgRykhn2 sOyJVXk9xVESGTwEPbTtfHM+4x0n0gC6GzfTMvwvZ9G6xoM0S4/+lgbaaa9t5tT/PrsvJiob kfqDrPbmSwr2G5mHnSM9M7B+w8odjmQFOwAjfcxoVIHxC4Cl/GAAKsX3KNKTspCHR0Yag78w i8duH/eEd4tB8twcqCi3aCgWoIrhjNS0myusmuA89kAWFFW5z26qNCOefovCx8drdMXQfMYv g5lRk821ZCNBosfRUvcMXoY6lTwHLIDrEfkJQtjxfdTlWQdwr0mM5ye7vd83AManSQwutgpI q+wE8CNY2VN9xAlE7OhcmWXlnAw3MJLW863SXdGlnkA3N+U4BoKQSIToGuXARQ14IMNvfeKX NphLPpUUnUNdfxAHu/S3tPTc/E/oePbHo794dnEm57LuuQINBFg2+xABEADZg/T+4o5qj4cw nd0G5pFy7ACxk28mSrLuva9tyzqPgRZ2bdPiwNXJUvBg1es2u81urekeUvGvnERB/TKekp25 4wU3I2lEhIXj5NVdLc6eU5czZQs4YEZbu1U5iqhhZmKhlLrhLlZv2whLOXRlLwi4jAzXIZAu 76mT813jbczl2dwxFxcT8XRzk9+dwzNTdOg75683uinMgskiiul+dzd6sumdOhRZR7YBT+xC wzfykOgBKnzfFscMwKR0iuHNB+VdEnZw80XGZi4N1ku81DHxmo2HG3icg7CwO1ih2jx8ik0r riIyMhJrTXgR1hF6kQnX7p2mXe6K0s8tQFK0ZZmYpZuGYYsV05OvU8yqrRVL/GYvy4Xgplm3 DuMuC7/A9/BfmxZVEPAS1gW6QQ8vSO4zf60zREKoSNYeiv+tURM2KOEj8tCMZN3k3sNASfoG fMvTvOjT0yzMbJsI1jwLwy5uA2JVdSLoWzBD8awZ2X/eCU9YDZeGuWmxzIHvkuMj8FfX8cK/ 2m437UA877eqmcgiEy/3B7XeHUipOL83gjfq4ETzVmxVswkVvZvR6j2blQVr+MhCZPq83Ota xNB7QptPxJuNRZ49gtT6uQkyGI+2daXqkj/Mot5tKxNKtM1Vbr/3b+AEMA7qLz7QjhgGJcie qp4b0gELjY1Oe9dBAXMiDwARAQABiQI8BBgBCAAmFiEEcM/SHOJt5ePBD8hO5T0WKDGD1rMF Alg2+xACGwwFCQlmAYAACgkQ5T0WKDGD1rOYSw/+P6fYSZjTJDAl9XNfXRjRRyJSfaw6N1pA Ahuu0MIa3djFRuFCrAHUaaFZf5V2iW5xhGnrhDwE1Ksf7tlstSne/G0a+Ef7vhUyeTn6U/0m +/BrsCsBUXhqeNuraGUtaleatQijXfuemUwgB+mE3B0SobE601XLo6MYIhPh8MG32MKO5kOY hB5jzyor7WoN3ETVNQoGgMzPVWIRElwpcXr+yGoTLAOpG7nkAUBBj9n9TPpSdt/npfok9ZfL /Q+ranrxb2Cy4tvOPxeVfR58XveX85ICrW9VHPVq9sJf/a24bMm6+qEg1V/G7u/AM3fM8U2m tdrTqOrfxklZ7beppGKzC1/WLrcr072vrdiN0icyOHQlfWmaPv0pUnW3AwtiMYngT96BevfA qlwaymjPTvH+cTXScnbydfOQW8220JQwykUe+sHRZfAF5TS2YCkQvsyf7vIpSqo/ttDk4+xc Z/wsLiWTgKlih2QYULvW61XU+mWsK8+ZlYUrRMpkauN4CJ5yTpvp+Orcz5KixHQmc5tbkLWf x0n1QFc1xxJhbzN+r9djSGGN/5IBDfUqSANC8cWzHpWaHmSuU3JSAMB/N+yQjIad2ztTckZY pwT6oxng29LzZspTYUEzMz3wK2jQHw+U66qBFk8whA7B2uAU1QdGyPgahLYSOa4XAEGb6wbI FEE= Message-ID: Date: Wed, 3 Jun 2020 17:30:14 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.1 MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:m+A5wHvMSSwj/4ZulG6se8q7GUNYt9SN+bV59H678/2LVxIt4GR Z9PVul/DlWe7u4Rl7ar5yIwP7IERy5eLj0hdBq2q5J2Su6QmkhEeQW3qlxdx1ST/gOmPXHD B14zHbvPHoR639eMkRy1xylG7W8T0uQCuymLLuV8EG7iy9PvbOZ/YRSz2SlbutEGTu+LFi0 xamNM/eF0p47MPGoIstfA== X-UI-Out-Filterresults: notjunk:1;V03:K0:ojT0uTotzlA=:eCQgDS8fiZu4U+MWxD/6fX Ye8uXMfpXsR2jh4HjmeCd9vBnRaTjaT2iH3gsjJhnUhbC+LSg5smfliCY18vN2ksA8Ag9lAQE v1xeKAutfZoRUgqfxdTbhZVvnx66nsBRqTZX2eLDxit5AqYP9x9plxcCkn42uHFJ6s3NEJWGw JNWDQtK7kl+cD83Gb2DTvtMMvCctfdW17Yc32o+8579BuMGo2QCkB9AagCzjjTF/3qDA1t9lq 1/5n9rwX/IvrtHDhsonQc/2KFoFbQTdGIZ5WGdIKa199zQioQcav6HyNSQI1RphSGeLmqVayk uaKyt594JuDT4kzMI19mmEyumsk5g6vmnStB577yjSBFyjDypbv+1xGFeGValHlFqWNyArt8k +hQ8tHTMC84MG8t/D2XRCtaF6wcFw1t48DGhtUyrDXGX7VWQcodM8dcQbVL+iOsIkCehJmibt W42IG2cVZ71l3nrMWK25iWYuGQDVKHgNWV/nuQnsZG4C9xprZeS4jHLSt/tCAtWnxUDh1ikb1 f5cFS//Zo1HHhH8uRBoL+SaQBcIoo7QvtbMaXHbwmuDAtI/lA0f3Dpxvifq3lSXF+4trEt8sc oHExGVNvUBlCYz/wvxUrrkECbzmOg4+fn1WI2SShrjfo76irp4zQUoLUcZQX+XCdjD7VKJ3lj Ysz+IouPmGYECyg5blnSJZ2LiFZixNMqWjbNYcdI6F9t7RIkmVJAg+UweiXmqbF39aOswKq7C m68efz0hfz8WAwMGiYSOwx9W9NlKOo2NLmYnM0YzGgYESzDog2I/nnK7tkUu1/OrqyORpDJ3+ 9ZpVnw+cbdfLaCFUaYo+u6379a7miKbHnyanPcN0FLpjEWcfBNF0cpUae27gzDKOaQWg65YnS A1EPX2kSJ2KsySyCcJKE7tEjU71Ryoaphu0JpdjBb5RiG2oJE3dILGCYwY0Qy3+Y4FEYVLcIC 9WgMLL+2znVvD/rYPih0/ni54vwhQDtD9tMwnZ9coPrnKGFjxDAK4kPolkJLdl2A5mZXbB6k3 F+uvki+bJAN+lwGwk1AdJKC7IWeAXe9EtjIQ4I/fDfgJdUs1x8A9M3oTl05w2iNn8igxyJwyL O3KGOJHaekmJvVfe0ykVJc9W9HQuTmqLLW8Bjb8A9ey9SajpkvFxCvEdVTqDaa5uUW6DcKTxz NNDEpWxB4OHE4WciXOVaKS1zX4i2X1kNRsfhpHWIy5cr4zRO5mXOGvUyQB6syl9j4rJCYF+zu zu5oo78EpDGVYwfxX Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > A deadlock caused by logbuf_lock occurs when panic: I suggest a few wording adjustments for this change description. Would you like to omit an extra space character at the beginning of this s= entence? > we try to re-init =E2=80=A6 We =E2=80=A6 > =E2=80=A6 deadlock, but it =E2=80=A6 here, because : =E2=80=A6 deadlock. But it =E2=80=A6 here because: > Firstly, =E2=80=A6 1. =E2=80=A6 > When the CPU bring down =E2=80=A6, =E2=80=A6 CPU willn't =E2=80=A6 CPU was brought down =E2=80=A6, =E2=80=A6 CPU will not > Secondly, =E2=80=A6 2. =E2=80=A6 > =E2=80=A6 callback, so if printk() =E2=80=A6 =E2=80=A6 callback. If printk() =E2=80=A6 > =E2=80=A6, deadlock will still occurs. Eg, =E2=80=A6 =E2=80=A6, deadlock will still occur. E. g. =E2=80=A6 Regards, Markus