From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F3135200113 for ; Sat, 13 Dec 2025 20:18:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765657099; cv=none; b=n47e6IeBdfh5Mopb76fEdeCYAAXW+wP1ewL81VFY7MDwCBpNeWiCWXPVHGtc1v9V8y+3b7oSSzrfA53zuN8bvA4Q4OMXFHboEaJ66Zyu/v4kAfFizqAwsz4+mXRlBlfX6R1PVgQ2NAcxKArzAxUxOCHmzAAJVDSLMcjzqBesxFY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765657099; c=relaxed/simple; bh=Idv7TluwVIQ13ed0OSNsHj17eP/l4hW8o42GI1PtluA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=mDeoZxkl+dSf+CnIj1Ab5ovF20uq9s0HdPraqCNH7M0D6/YOpw1l57bmf3LaYUHQjbwZso+GVRGo4odCwkBBHT++ODE5A03jlrJaErCxBwhq8qpwPEaOloYGaptL8n1hO0GZNeASCZWH2BgvG8ENYYfzSndpPUPZbOYW89i/qAI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=ezgV50TG; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=BPKRCo5/; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="ezgV50TG"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="BPKRCo5/" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1765657095; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=HqHdA42kwnSw7rnAek6DVQPknyRqQU68hpye3QGVSBc=; b=ezgV50TGVb9Zf4VA+vK3m/WTmGiDb3y/nr69Ce+qWo6+Rk9ALVUeAB8b2P/FDLwPns8x19 W577pMaYD36w4ArSLviwfs5AW3LxV3lsajNLqytQ+ApUITpcLGGWhsubm3pKoHRKounwkU ZRKzF7/yP0udyJBBl4IB0/OzzP5VoC4= Received: from mail-wm1-f69.google.com (mail-wm1-f69.google.com [209.85.128.69]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-520-XL9KwOYCNc2XPYOZ-TgSfA-1; Sat, 13 Dec 2025 15:18:13 -0500 X-MC-Unique: XL9KwOYCNc2XPYOZ-TgSfA-1 X-Mimecast-MFC-AGG-ID: XL9KwOYCNc2XPYOZ-TgSfA_1765657092 Received: by mail-wm1-f69.google.com with SMTP id 5b1f17b1804b1-47921784b97so17220555e9.0 for ; Sat, 13 Dec 2025 12:18:13 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1765657092; x=1766261892; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:organization:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to; bh=HqHdA42kwnSw7rnAek6DVQPknyRqQU68hpye3QGVSBc=; b=BPKRCo5/YE+WSJAHIjRbMC/pI5bfSgGeRxDJxkr9oAQRMQUq1163z7sAr/+IvfBXJo qou7FElfuFtGJazF5E8Jzgvp/uQzKsDAspICKHxUVDfyfdDTqJhR2flIA2KAf/edd2uK 4Ei6SOLKOR5YYehGraOjaqFQbb4LVEMZrwUHRHO2i7wfR68APFWxHF6MDb3KI4pkjw71 uzbTq2Din2/3yXXli++FA2WTXCkAbFg4eZxiynX38w4m+oIY8hAES/75Aiya3B0pUSsP JgGDiEXAXicfZCqNsE25EI89NHe1BA2J1l82eb2ho1T5q20VuTZqqs5KHfXNjeEg15Ry DAzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1765657092; x=1766261892; h=content-transfer-encoding:in-reply-to:organization:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=HqHdA42kwnSw7rnAek6DVQPknyRqQU68hpye3QGVSBc=; b=ljVTUOgiQUtjQN/1K7PmN+XKVEFKKK/Vtc9c4SyYltaHczDCacZpDEMsuq1oMKkF52 SAtX07rXIuzVXJWZAUrug+vpumrjHzdJBEdZSDjiRf3yENguF6mGT80UgEnhJFH2tztQ aNnpKnwxfGlIK4nJ2ljfMDx9LmH7FysDG0rZnAh+soVzBa5x8vd7nEt+lFtnEIuvxzG8 vqv0IkccJBavJLmnf+2PS6z2cEJufnFEE58fdyb2CvkM3LrsOpmiVBo1+uQB5Xz6WhUD m0WBmYRDKAxqmDUpRthssBn1I+W/WEPuLP8JJUxWp88bAzpkYnbxjyPnoWOrm4M6Hqbt yMow== X-Gm-Message-State: AOJu0YzvQrys0GAT0Ix3qM140mSlbtUInlTozzQ61/6wHG+rv0AAPmNQ qujSPcUADhAqEJn8ieANSjXDgYLAGFJBviBGbOzt5GiGZUMovOddVK203rnHAz9ShZOIuhwOS5e SYNwSXzhwjsFgx1Vviy0J51y3FfZUIh1Udxs5ln0Jod6v58wEojQcKOpM5geasp0fwg== X-Gm-Gg: AY/fxX6A5nxMfl+E8qh5K8/plfScMs/p/+Z4SI5/3rItBwqt7hKyDHDaCvJxm22I3Lx r6AbO6Bca6T8ZFEYJaYbnNTfgIYt5+yDpEr4DFxB9xaPCqMUgUNPYHzE5R6VkUBox4wm4ZL2k3p LV9nswzfH9YDVMgePuVZQR5iLnHW/jgkSNU41E3bEvY4Q9ehm2ctzy77lGljw7AeBuZz0c4mId2 IvR2EFrw43B6HFV9e4Pb6fIqLjpZmDN7ccBLNDKAeS82nfw5rZLsYuap72LwnN27ES6pWPoeCQR HU6js/BRC6wlFRkIpknHwQb7M/UdkgjwIY3T0kNyn0bBnpIeW/rDQ5gcO8ViO4gC8IKb+jcQjUH z+sFctyHhsegxhQ== X-Received: by 2002:adf:ecc1:0:b0:42f:bab5:9533 with SMTP id ffacd0b85a97d-42fbab595f7mr3809913f8f.17.1765657091660; Sat, 13 Dec 2025 12:18:11 -0800 (PST) X-Google-Smtp-Source: AGHT+IG/Sb62URJOZC68mP6QsJEjRVxwQ6ZNCww+v7vq3fA22v3SHO3l7CaahkXkg1bSWAD0OdX/zA== X-Received: by 2002:adf:ecc1:0:b0:42f:bab5:9533 with SMTP id ffacd0b85a97d-42fbab595f7mr3809905f8f.17.1765657091246; Sat, 13 Dec 2025 12:18:11 -0800 (PST) Received: from [192.168.0.111] ([212.20.115.16]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-42fa8b85d1esm19472441f8f.26.2025.12.13.12.18.10 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 13 Dec 2025 12:18:10 -0800 (PST) Message-ID: <1f8a360d-89ea-4621-9e48-a20e2c42193b@redhat.com> Date: Sat, 13 Dec 2025 21:18:10 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Beta Subject: Re: UBSAN: shift-out-of-bounds in drivers/gpu/drm/display/drm_dp_mst_topology.c:4575:36 To: imre.deak@intel.com Cc: LKML References: <072774ed-cb7b-4700-821b-b2c743b37222@redhat.com> Content-Language: en-US, cs From: Zdenek Kabelac Organization: RedHat In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Dne 12. 12. 25 v 20:14 Imre Deak napsal(a): > Hi, > > On Fri, Dec 12, 2025 at 07:55:12PM +0100, Zdenek Kabelac wrote: >> Hi >> >> I've noticed this in my message log while suspending my P1 machine >> (and unplugging it from my docking station). >> >> ---- >> kernel: UBSAN: shift-out-of-bounds in >> drivers/gpu/drm/display/drm_dp_mst_topology.c:4575:36 >> kernel: shift exponent -1 is negative >> >> My laptop: ThinkPad P16v Gen 1, 64G RAM, 16 AMD Cores > > The WARN itself should be removed by > https://lore.kernel.org/all/20251119094650.799135-1-suraj.kandpal@intel.com > > however, the above fix doesn't have other effects besides removing the > WARN message/stack trace, so the slow-down you describe must have a > differrent root cause than using a -1 as a shift value above. A wild > guess is that it's some timeout trying to access the sink (which is > inaccissible because the sink was unplugged) and the corresponding MST > timeout being rather long (up to 4 sec per MST programming step). > > I'd suggest opening an AMD DRM driver ticket to get a better idea, > attaching there a dmesg log taken after booting with debug enabled (at > least adding the drm.debug=0x15e kernel param) and reproducing the > problem. Ok - I think I've found matching symptoms in this thread: https://discussion.fedoraproject.org/t/f41-is-sluggish-after-resuming-from-suspend-fixed-by-a-restart/147352/2 I guess I need to start to 'think' when I plug & unplug cables from the laptop before suspend... Regards Zdenek