From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 65D11C43217 for ; Thu, 1 Dec 2022 19:33:57 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8FA0110E156; Thu, 1 Dec 2022 19:33:53 +0000 (UTC) Received: from mail-oa1-x33.google.com (mail-oa1-x33.google.com [IPv6:2001:4860:4864:20::33]) by gabe.freedesktop.org (Postfix) with ESMTPS id 73BB010E155; Thu, 1 Dec 2022 19:33:49 +0000 (UTC) Received: by mail-oa1-x33.google.com with SMTP id 586e51a60fabf-1433ef3b61fso3287787fac.10; Thu, 01 Dec 2022 11:33:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=VPkQQERyjiDmblFdMpvetG3Txhv1fALmSUiNK4uispU=; b=JIVTb6kVxC2+GkogklTf3iO7DdD+uMRGAWgl1zuxAMxh7CuiezggfqAOEft6c/q8eW RJLqfbNwTaiLr3hJaXKVcu91q0hjddR3wiaXAUojE/zXibeNisE9YFCIV6F6JTV9ClHW YNWBOrfFh0xZarYfsulryI7QCQJ/04teja9lHFjLB6w0YTLDhiPctaZpMoDUwsyOn6Zn NyP/dwmmWZDQcEh54JVmq0JV5UGQD5s9g15X8MIpt6Y9ur1MGU2B1L2g7muF1jku24Ap DZS/aSJ+FRrTBJ1VBsf3tRZypBAFZteumLCs6GvgAl1iHbfZjxl/iKXOHF9PTRYbtnqQ nc9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=VPkQQERyjiDmblFdMpvetG3Txhv1fALmSUiNK4uispU=; b=j3M8EgicUhP0q5hjnP5LpotBA0+In1lJi3rY05i6UtkFzN0Ny13eErojrp7TMWeajs zhFWvCWrW8viDh+ijEOKZc7ibnWNIi8SoCJPPoxpb0YNaNealV2OyJJbtAD+2rWNEb1e OCsnRUyvAvaMBsMhAbMIRs10gaP7dXFnHKdU5tMkp3NB+EjFQqoRs3J8v5o97UWrtNwp VOgb4TKBf9ZgqGX8qJoizp+qx8p1O2VQ4T4gsWXE+K1/Sm+q8bCrC3J/mSQyhOb0Gu7y IdT1y3FDybPpLmZh79k3C2Vh0OXtgZYhXSqx5ZFXGdQSo4n2VX5/R17k4hgOn8rQLvJb juUw== X-Gm-Message-State: ANoB5plsVr/S1xY23zGhYgLhHQ0i3MGKtKx1X3Iyg6cCgyM9yA1UBdRc tnGm+cPSRi7OXgqGURXt1zwi0qB9l0f2nvU+U9Q= X-Google-Smtp-Source: AA0mqf5Y1FCdimrFaHTrU8Rv9VYLNayXBm6wkTjy2CMyzp5Sfd1yy5/UTaWmVF4ZZMuRF85ezZkOgwQrLlHPdjOhg84= X-Received: by 2002:a05:6870:b01e:b0:131:f559:461b with SMTP id y30-20020a056870b01e00b00131f559461bmr37615734oae.38.1669923228590; Thu, 01 Dec 2022 11:33:48 -0800 (PST) MIME-Version: 1.0 References: <20221111194957.4046771-1-joel@joelfernandes.org> <20221111194957.4046771-2-joel@joelfernandes.org> <899db0f8-7b8a-ed8f-30b8-4f630da1298d@quicinc.com> In-Reply-To: From: Rob Clark Date: Thu, 1 Dec 2022 11:33:40 -0800 Message-ID: Subject: Re: [PATCH 2/2] adreno: Detect shutdown during get_param() To: Joel Fernandes Content-Type: text/plain; charset="UTF-8" X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Rob Clark , Emma Anholt , Akhil P Oommen , freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Ricardo Ribalda , Vladimir Lypak , linux-kernel@vger.kernel.org, Steven Rostedt , Abhinav Kumar , Sean Paul , dri-devel@lists.freedesktop.org, Ross Zwisler , Dmitry Baryshkov Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On Thu, Dec 1, 2022 at 10:42 AM Joel Fernandes wrote: > > On Sat, Nov 12, 2022 at 6:35 PM Rob Clark wrote: > > > > On Fri, Nov 11, 2022 at 1:28 PM Akhil P Oommen wrote: > > > > > > On 11/12/2022 1:19 AM, Joel Fernandes (Google) wrote: > > > > Even though the GPU is shut down, during kexec reboot we can have userspace > > > > still running. This is especially true if KEXEC_JUMP is not enabled, because we > > > > do not freeze userspace in this case. > > > > > > > > To prevent crashes, track that the GPU is shutdown and prevent get_param() from > > > > accessing GPU resources if we find it shutdown. > > > > > > > > This fixes the following crash during kexec reboot on an ARM64 device with adreno GPU: > > > > > > > > [ 292.534314] Kernel panic - not syncing: Asynchronous SError Interrupt > > > > [ 292.534323] Hardware name: Google Lazor (rev3 - 8) with LTE (DT) > > > > [ 292.534326] Call trace: > > > > [ 292.534328] dump_backtrace+0x0/0x1d4 > > > > [ 292.534337] show_stack+0x20/0x2c > > > > [ 292.534342] dump_stack_lvl+0x60/0x78 > > > > [ 292.534347] dump_stack+0x18/0x38 > > > > [ 292.534352] panic+0x148/0x3b0 > > > > [ 292.534357] nmi_panic+0x80/0x94 > > > > [ 292.534364] arm64_serror_panic+0x70/0x7c > > > > [ 292.534369] do_serror+0x0/0x7c > > > > [ 292.534372] do_serror+0x54/0x7c > > > > [ 292.534377] el1h_64_error_handler+0x34/0x4c > > > > [ 292.534381] el1h_64_error+0x7c/0x80 > > > > [ 292.534386] el1_interrupt+0x20/0x58 > > > > [ 292.534389] el1h_64_irq_handler+0x18/0x24 > > > > [ 292.534395] el1h_64_irq+0x7c/0x80 > > > > [ 292.534399] local_daif_inherit+0x10/0x18 > > > > [ 292.534405] el1h_64_sync_handler+0x48/0xb4 > > > > [ 292.534410] el1h_64_sync+0x7c/0x80 > > > > [ 292.534414] a6xx_gmu_set_oob+0xbc/0x1fc > > > > [ 292.534422] a6xx_get_timestamp+0x40/0xb4 > > > > [ 292.534426] adreno_get_param+0x12c/0x1e0 > > > > [ 292.534433] msm_ioctl_get_param+0x64/0x70 > > > > [ 292.534440] drm_ioctl_kernel+0xe8/0x158 > > > > [ 292.534448] drm_ioctl+0x208/0x320 > > > > [ 292.534453] __arm64_sys_ioctl+0x98/0xd0 > > > > [ 292.534461] invoke_syscall+0x4c/0x118 > > > > [ 292.534467] el0_svc_common+0x98/0x104 > > > > [ 292.534473] do_el0_svc+0x30/0x80 > > > > [ 292.534478] el0_svc+0x20/0x50 > > > > [ 292.534481] el0t_64_sync_handler+0x78/0x108 > > > > [ 292.534485] el0t_64_sync+0x1a4/0x1a8 > > > > [ 292.534632] Kernel Offset: 0x1a5f800000 from 0xffffffc008000000 > > > > [ 292.534635] PHYS_OFFSET: 0x80000000 > > > > [ 292.534638] CPU features: 0x40018541,a3300e42 > > > > [ 292.534644] Memory Limit: none > > > > > > > > Cc: Rob Clark > > > > Cc: Steven Rostedt > > > > Cc: Ricardo Ribalda > > > > Cc: Ross Zwisler > > > > Signed-off-by: Joel Fernandes (Google) > > > > --- > > > > drivers/gpu/drm/msm/adreno/adreno_device.c | 1 + > > > > drivers/gpu/drm/msm/adreno/adreno_gpu.c | 2 +- > > > > drivers/gpu/drm/msm/msm_gpu.h | 3 +++ > > > > 3 files changed, 5 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c > > > > index f0cff62812c3..03d912dc0130 100644 > > > > --- a/drivers/gpu/drm/msm/adreno/adreno_device.c > > > > +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c > > > > @@ -612,6 +612,7 @@ static void adreno_shutdown(struct platform_device *pdev) > > > > { > > > > struct msm_gpu *gpu = dev_to_gpu(&pdev->dev); > > > > > > > > + gpu->is_shutdown = true; > > > > WARN_ON_ONCE(adreno_system_suspend(&pdev->dev)); > > > > } > > > > > > > > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c > > > > index 382fb7f9e497..6903c6892469 100644 > > > > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c > > > > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c > > > > @@ -251,7 +251,7 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_file_private *ctx, > > > > struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu); > > > > > > > > /* No pointer params yet */ > > > > - if (*len != 0) > > > > + if (*len != 0 || gpu->is_shutdown) > > > > return -EINVAL; > > > This will race with shutdown. Probably, propagating back the return > > > value of pm_runtime_get() in every possible ioctl call path is the right > > > thing to do. > > > > > > I have never thought about this scenario. Do you know why userspace is > > > not freezed before kexec? > > > > So userspace not being frozen seems like the root issue, and is likely > > to cause all sorts of other whack-a-mole problems. I guess I'd like > > to know if this is the expected behavior? > > We tried that. Freezing before kexec seems to cause issues for ALSA as > Ricardo found: > https://lore.kernel.org/lkml/202211281209.mnBLzQ2I-lkp@intel.com/T/ > > That patch is still TBD due to disagreement on the right approach to > fix, so I don't think freezing before shutting down devices is viable > at the moment. > > I am checking Ricardo if we can do something like util-linux's > shutdown code which sends SIGTERM to all processes: > https://kernel.googlesource.com/pub/scm/utils/util-linux/util-linux/+/v2.8/login-utils/shutdown.c#273 > , before issuing the kexec-reboot. > > Maybe, a more graceful shutdown from kexec-lite, will prevent the > kexec-reboot it does from crashing? Though in my view that would still > be a small copout instead of fixing the real issue, which is the > kernel crashing for any reason. The problem is that pm_runtime_force_suspend() yanks the rug out from under the driver from a runpm PoV.. generally this is ok (as long as scheduler kthread is parked) because we don't have to worry about userspace ;-) > > If so, we should probably look at > > drm_dev_is_unplugged()/drm_dev_unplug()/etc rather than trying to NIH > > that mechanism. We would need to sprinkle drm_dev_is_unplugged() > > checks more widely, and also ensure that the scheduler kthread(s) gets > > parked. But it would be nice to know first if we are just trying to > > paper over a kexec bug. > > Agreed. I think we still patch 1/2 whether the SIGTERM trick mentioned > above, works or not. I will await discussions with Ricardo before > reposting that one. Yeah, I think I'm waiting on a v2 of that one ;-) BR, -R > Cheers, > > -- Joel From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DA088C43217 for ; Thu, 1 Dec 2022 19:34:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231280AbiLATe4 (ORCPT ); Thu, 1 Dec 2022 14:34:56 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53534 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230465AbiLATej (ORCPT ); Thu, 1 Dec 2022 14:34:39 -0500 Received: from mail-oa1-x31.google.com (mail-oa1-x31.google.com [IPv6:2001:4860:4864:20::31]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 61D799381C; Thu, 1 Dec 2022 11:33:49 -0800 (PST) Received: by mail-oa1-x31.google.com with SMTP id 586e51a60fabf-14286d5ebc3so3335979fac.3; Thu, 01 Dec 2022 11:33:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=VPkQQERyjiDmblFdMpvetG3Txhv1fALmSUiNK4uispU=; b=JIVTb6kVxC2+GkogklTf3iO7DdD+uMRGAWgl1zuxAMxh7CuiezggfqAOEft6c/q8eW RJLqfbNwTaiLr3hJaXKVcu91q0hjddR3wiaXAUojE/zXibeNisE9YFCIV6F6JTV9ClHW YNWBOrfFh0xZarYfsulryI7QCQJ/04teja9lHFjLB6w0YTLDhiPctaZpMoDUwsyOn6Zn NyP/dwmmWZDQcEh54JVmq0JV5UGQD5s9g15X8MIpt6Y9ur1MGU2B1L2g7muF1jku24Ap DZS/aSJ+FRrTBJ1VBsf3tRZypBAFZteumLCs6GvgAl1iHbfZjxl/iKXOHF9PTRYbtnqQ nc9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=VPkQQERyjiDmblFdMpvetG3Txhv1fALmSUiNK4uispU=; b=b9mz2T3OH3VHU2gwUE8hPcy6R/Crph2+sDqApEJ5uU0tODp9JbL3x5iLki7OGvjFLt WZmw0eamB/CikgwHyQ/GkSQPRrQcebg5r/Zh2JyrCGPrLh+Bv1D91FmDVcz8zJUX4arB k0z+OyiRdP3KhwK/nQT5/GbWd19x+mVDgi06jeEqZu/4Uqgrf6HDh4nvbg/mIMIUcQzh ING1O+dgQCiRrSWlu/2jNN4zGxq/5HpLR/xHUylj6Om7BhQ3uztlp4XJ/lNUv54rsNjG 5lC+KZD4qVLYUJCMNIBZunkc93o/9oeFBDFdwz7Qcu+s2jf8Vjibl3sraCmI4xW1oKHB xyww== X-Gm-Message-State: ANoB5pklnd+GpM+bf2FyIzvLXuzaLJr27M68Bk3XiMaGAsM4u+CGDuuN /Kb9B2gtqjPEly65yr8yIEQJ8OdMg053ug8IrtvVtO85 X-Google-Smtp-Source: AA0mqf5Y1FCdimrFaHTrU8Rv9VYLNayXBm6wkTjy2CMyzp5Sfd1yy5/UTaWmVF4ZZMuRF85ezZkOgwQrLlHPdjOhg84= X-Received: by 2002:a05:6870:b01e:b0:131:f559:461b with SMTP id y30-20020a056870b01e00b00131f559461bmr37615734oae.38.1669923228590; Thu, 01 Dec 2022 11:33:48 -0800 (PST) MIME-Version: 1.0 References: <20221111194957.4046771-1-joel@joelfernandes.org> <20221111194957.4046771-2-joel@joelfernandes.org> <899db0f8-7b8a-ed8f-30b8-4f630da1298d@quicinc.com> In-Reply-To: From: Rob Clark Date: Thu, 1 Dec 2022 11:33:40 -0800 Message-ID: Subject: Re: [PATCH 2/2] adreno: Detect shutdown during get_param() To: Joel Fernandes Cc: Akhil P Oommen , linux-kernel@vger.kernel.org, Rob Clark , Steven Rostedt , Ricardo Ribalda , Ross Zwisler , Abhinav Kumar , Daniel Vetter , David Airlie , Dmitry Baryshkov , dri-devel@lists.freedesktop.org, Emma Anholt , freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Sean Paul , Vladimir Lypak Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On Thu, Dec 1, 2022 at 10:42 AM Joel Fernandes wrote: > > On Sat, Nov 12, 2022 at 6:35 PM Rob Clark wrote: > > > > On Fri, Nov 11, 2022 at 1:28 PM Akhil P Oommen wrote: > > > > > > On 11/12/2022 1:19 AM, Joel Fernandes (Google) wrote: > > > > Even though the GPU is shut down, during kexec reboot we can have userspace > > > > still running. This is especially true if KEXEC_JUMP is not enabled, because we > > > > do not freeze userspace in this case. > > > > > > > > To prevent crashes, track that the GPU is shutdown and prevent get_param() from > > > > accessing GPU resources if we find it shutdown. > > > > > > > > This fixes the following crash during kexec reboot on an ARM64 device with adreno GPU: > > > > > > > > [ 292.534314] Kernel panic - not syncing: Asynchronous SError Interrupt > > > > [ 292.534323] Hardware name: Google Lazor (rev3 - 8) with LTE (DT) > > > > [ 292.534326] Call trace: > > > > [ 292.534328] dump_backtrace+0x0/0x1d4 > > > > [ 292.534337] show_stack+0x20/0x2c > > > > [ 292.534342] dump_stack_lvl+0x60/0x78 > > > > [ 292.534347] dump_stack+0x18/0x38 > > > > [ 292.534352] panic+0x148/0x3b0 > > > > [ 292.534357] nmi_panic+0x80/0x94 > > > > [ 292.534364] arm64_serror_panic+0x70/0x7c > > > > [ 292.534369] do_serror+0x0/0x7c > > > > [ 292.534372] do_serror+0x54/0x7c > > > > [ 292.534377] el1h_64_error_handler+0x34/0x4c > > > > [ 292.534381] el1h_64_error+0x7c/0x80 > > > > [ 292.534386] el1_interrupt+0x20/0x58 > > > > [ 292.534389] el1h_64_irq_handler+0x18/0x24 > > > > [ 292.534395] el1h_64_irq+0x7c/0x80 > > > > [ 292.534399] local_daif_inherit+0x10/0x18 > > > > [ 292.534405] el1h_64_sync_handler+0x48/0xb4 > > > > [ 292.534410] el1h_64_sync+0x7c/0x80 > > > > [ 292.534414] a6xx_gmu_set_oob+0xbc/0x1fc > > > > [ 292.534422] a6xx_get_timestamp+0x40/0xb4 > > > > [ 292.534426] adreno_get_param+0x12c/0x1e0 > > > > [ 292.534433] msm_ioctl_get_param+0x64/0x70 > > > > [ 292.534440] drm_ioctl_kernel+0xe8/0x158 > > > > [ 292.534448] drm_ioctl+0x208/0x320 > > > > [ 292.534453] __arm64_sys_ioctl+0x98/0xd0 > > > > [ 292.534461] invoke_syscall+0x4c/0x118 > > > > [ 292.534467] el0_svc_common+0x98/0x104 > > > > [ 292.534473] do_el0_svc+0x30/0x80 > > > > [ 292.534478] el0_svc+0x20/0x50 > > > > [ 292.534481] el0t_64_sync_handler+0x78/0x108 > > > > [ 292.534485] el0t_64_sync+0x1a4/0x1a8 > > > > [ 292.534632] Kernel Offset: 0x1a5f800000 from 0xffffffc008000000 > > > > [ 292.534635] PHYS_OFFSET: 0x80000000 > > > > [ 292.534638] CPU features: 0x40018541,a3300e42 > > > > [ 292.534644] Memory Limit: none > > > > > > > > Cc: Rob Clark > > > > Cc: Steven Rostedt > > > > Cc: Ricardo Ribalda > > > > Cc: Ross Zwisler > > > > Signed-off-by: Joel Fernandes (Google) > > > > --- > > > > drivers/gpu/drm/msm/adreno/adreno_device.c | 1 + > > > > drivers/gpu/drm/msm/adreno/adreno_gpu.c | 2 +- > > > > drivers/gpu/drm/msm/msm_gpu.h | 3 +++ > > > > 3 files changed, 5 insertions(+), 1 deletion(-) > > > > > > > > diff --git a/drivers/gpu/drm/msm/adreno/adreno_device.c b/drivers/gpu/drm/msm/adreno/adreno_device.c > > > > index f0cff62812c3..03d912dc0130 100644 > > > > --- a/drivers/gpu/drm/msm/adreno/adreno_device.c > > > > +++ b/drivers/gpu/drm/msm/adreno/adreno_device.c > > > > @@ -612,6 +612,7 @@ static void adreno_shutdown(struct platform_device *pdev) > > > > { > > > > struct msm_gpu *gpu = dev_to_gpu(&pdev->dev); > > > > > > > > + gpu->is_shutdown = true; > > > > WARN_ON_ONCE(adreno_system_suspend(&pdev->dev)); > > > > } > > > > > > > > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c > > > > index 382fb7f9e497..6903c6892469 100644 > > > > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c > > > > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c > > > > @@ -251,7 +251,7 @@ int adreno_get_param(struct msm_gpu *gpu, struct msm_file_private *ctx, > > > > struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu); > > > > > > > > /* No pointer params yet */ > > > > - if (*len != 0) > > > > + if (*len != 0 || gpu->is_shutdown) > > > > return -EINVAL; > > > This will race with shutdown. Probably, propagating back the return > > > value of pm_runtime_get() in every possible ioctl call path is the right > > > thing to do. > > > > > > I have never thought about this scenario. Do you know why userspace is > > > not freezed before kexec? > > > > So userspace not being frozen seems like the root issue, and is likely > > to cause all sorts of other whack-a-mole problems. I guess I'd like > > to know if this is the expected behavior? > > We tried that. Freezing before kexec seems to cause issues for ALSA as > Ricardo found: > https://lore.kernel.org/lkml/202211281209.mnBLzQ2I-lkp@intel.com/T/ > > That patch is still TBD due to disagreement on the right approach to > fix, so I don't think freezing before shutting down devices is viable > at the moment. > > I am checking Ricardo if we can do something like util-linux's > shutdown code which sends SIGTERM to all processes: > https://kernel.googlesource.com/pub/scm/utils/util-linux/util-linux/+/v2.8/login-utils/shutdown.c#273 > , before issuing the kexec-reboot. > > Maybe, a more graceful shutdown from kexec-lite, will prevent the > kexec-reboot it does from crashing? Though in my view that would still > be a small copout instead of fixing the real issue, which is the > kernel crashing for any reason. The problem is that pm_runtime_force_suspend() yanks the rug out from under the driver from a runpm PoV.. generally this is ok (as long as scheduler kthread is parked) because we don't have to worry about userspace ;-) > > If so, we should probably look at > > drm_dev_is_unplugged()/drm_dev_unplug()/etc rather than trying to NIH > > that mechanism. We would need to sprinkle drm_dev_is_unplugged() > > checks more widely, and also ensure that the scheduler kthread(s) gets > > parked. But it would be nice to know first if we are just trying to > > paper over a kexec bug. > > Agreed. I think we still patch 1/2 whether the SIGTERM trick mentioned > above, works or not. I will await discussions with Ricardo before > reposting that one. Yeah, I think I'm waiting on a v2 of that one ;-) BR, -R > Cheers, > > -- Joel