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 X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 68CE9C433E3 for ; Tue, 14 Jul 2020 10:49:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 42EF322203 for ; Tue, 14 Jul 2020 10:49:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=ffwll.ch header.i=@ffwll.ch header.b="bOeL2MUd" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725884AbgGNKtP (ORCPT ); Tue, 14 Jul 2020 06:49:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48018 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726534AbgGNKtO (ORCPT ); Tue, 14 Jul 2020 06:49:14 -0400 Received: from mail-wr1-x444.google.com (mail-wr1-x444.google.com [IPv6:2a00:1450:4864:20::444]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5C6A5C061794 for ; Tue, 14 Jul 2020 03:49:14 -0700 (PDT) Received: by mail-wr1-x444.google.com with SMTP id k6so20747907wrn.3 for ; Tue, 14 Jul 2020 03:49:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ffwll.ch; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:content-transfer-encoding:in-reply-to; bh=XFyCObAFNGAkAD33iucRxardqlG+NdnL+BA8ka5PPr4=; b=bOeL2MUd2f8AlWSJD3wmjK7kX/u8xZmjsUmMQeJzGK+l98O+GbJDKEx2q+dtP0Ysuw ahdh9hOxfLzdYsrsSCIb4+jsBwaVOfOB9g1F7JaVOZ01TKCuMezHAGJnllnKMSUhc5F+ Oz3Dlt8i1yKPbH5ek0krA47zpw8DZA2RsafPc= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=XFyCObAFNGAkAD33iucRxardqlG+NdnL+BA8ka5PPr4=; b=Af0LTU8ax5yzOs6RZnBuwvY/RrNU8p0jnfakVWZDRkSKABWx9ORWiIDsbaBhLfw/LN LbMMiPo4L9BcLSuezaWjGudSaFdLXSV4wYYzeSivmMFjAW+eSUuisZIrh0Pigwa4X75+ u3+4jK+m1oCiBwnMtywTDDxQ5qX7spmGvAsHx9pMdnCvzaPCYKVMEEVODhCbCIpXGgII +OhVohf4Aa/wTIh9VhrF+KSq9ISidxWzVnEpyKrYVla1N2/Cvc8ZivmTB2FyMaCBHAwN osjkW0bTeTtOS6ig920hcxVgpCpGEtl4TkscF8rPzAADVjmyp9mJ72fXyLSoNkMNnWET Csbg== X-Gm-Message-State: AOAM533fo3Fjc/AjBswlw3+g3XFOdGIcjjweQJkQTKTSJQNoG1gc4kNd ZMLO7XuMT/6sUwLEoecy99BKFg== X-Google-Smtp-Source: ABdhPJxzCDVzf3ULPsu9gK9KiSaB34ZTvYO1lf6Ch0WaVTCD95UxXPy23Q0JcDyFOFTm8A13sseYqQ== X-Received: by 2002:adf:c44d:: with SMTP id a13mr4551346wrg.205.1594723752919; Tue, 14 Jul 2020 03:49:12 -0700 (PDT) Received: from phenom.ffwll.local ([2a02:168:57f4:0:efd0:b9e5:5ae6:c2fa]) by smtp.gmail.com with ESMTPSA id u17sm27474975wrp.70.2020.07.14.03.49.11 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Jul 2020 03:49:12 -0700 (PDT) Date: Tue, 14 Jul 2020 12:49:10 +0200 From: Daniel Vetter To: DRI Development Cc: Intel Graphics Development , linux-rdma@vger.kernel.org, Daniel Vetter , linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org, amd-gfx@lists.freedesktop.org, Chris Wilson , Maarten Lankhorst , Christian =?iso-8859-1?Q?K=F6nig?= , Daniel Vetter Subject: Re: [PATCH 19/25] drm/amdgpu: s/GFP_KERNEL/GFP_ATOMIC in scheduler code Message-ID: <20200714104910.GC3278063@phenom.ffwll.local> References: <20200707201229.472834-1-daniel.vetter@ffwll.ch> <20200707201229.472834-20-daniel.vetter@ffwll.ch> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200707201229.472834-20-daniel.vetter@ffwll.ch> X-Operating-System: Linux phenom 5.6.0-1-amd64 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org On Tue, Jul 07, 2020 at 10:12:23PM +0200, Daniel Vetter wrote: > My dma-fence lockdep annotations caught an inversion because we > allocate memory where we really shouldn't: > > kmem_cache_alloc+0x2b/0x6d0 > amdgpu_fence_emit+0x30/0x330 [amdgpu] > amdgpu_ib_schedule+0x306/0x550 [amdgpu] > amdgpu_job_run+0x10f/0x260 [amdgpu] > drm_sched_main+0x1b9/0x490 [gpu_sched] > kthread+0x12e/0x150 > > Trouble right now is that lockdep only validates against GFP_FS, which > would be good enough for shrinkers. But for mmu_notifiers we actually > need !GFP_ATOMIC, since they can be called from any page laundering, > even if GFP_NOFS or GFP_NOIO are set. > > I guess we should improve the lockdep annotations for > fs_reclaim_acquire/release. > > Ofc real fix is to properly preallocate this fence and stuff it into > the amdgpu job structure. But GFP_ATOMIC gets the lockdep splat out of > the way. > > v2: Two more allocations in scheduler paths. > > Frist one: > > __kmalloc+0x58/0x720 > amdgpu_vmid_grab+0x100/0xca0 [amdgpu] > amdgpu_job_dependency+0xf9/0x120 [amdgpu] > drm_sched_entity_pop_job+0x3f/0x440 [gpu_sched] > drm_sched_main+0xf9/0x490 [gpu_sched] > > Second one: > > kmem_cache_alloc+0x2b/0x6d0 > amdgpu_sync_fence+0x7e/0x110 [amdgpu] > amdgpu_vmid_grab+0x86b/0xca0 [amdgpu] > amdgpu_job_dependency+0xf9/0x120 [amdgpu] > drm_sched_entity_pop_job+0x3f/0x440 [gpu_sched] > drm_sched_main+0xf9/0x490 [gpu_sched] > > Cc: linux-media@vger.kernel.org > Cc: linaro-mm-sig@lists.linaro.org > Cc: linux-rdma@vger.kernel.org > Cc: amd-gfx@lists.freedesktop.org > Cc: intel-gfx@lists.freedesktop.org > Cc: Chris Wilson > Cc: Maarten Lankhorst > Cc: Christian König > Signed-off-by: Daniel Vetter Has anyone from amd side started looking into how to fix this properly? I looked a bit into fixing this with mempool, and the big guarantee we need is that - there's a hard upper limit on how many allocations we minimally need to guarantee forward progress. And the entire vmid allocation and amdgpu_sync_fence stuff kinda makes me question that's a valid assumption. - mempool_free must be called without any locks in the way which are held while we call mempool_alloc. Otherwise we again have a nice deadlock with no forward progress. I tried auditing that, but got lost in amdgpu and scheduler code. Some lockdep annotations for mempool.c might help, but they're not going to catch everything. Plus it would be again manual annotations because this is yet another cross-release issue. So not sure that helps at all. iow, not sure what to do here. Ideas? Cheers, Daniel > --- > drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c | 2 +- > drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c | 2 +- > drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 2 +- > 3 files changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c > index 8d84975885cd..a089a827fdfe 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_fence.c > @@ -143,7 +143,7 @@ int amdgpu_fence_emit(struct amdgpu_ring *ring, struct dma_fence **f, > uint32_t seq; > int r; > > - fence = kmem_cache_alloc(amdgpu_fence_slab, GFP_KERNEL); > + fence = kmem_cache_alloc(amdgpu_fence_slab, GFP_ATOMIC); > if (fence == NULL) > return -ENOMEM; > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c > index 267fa45ddb66..a333ca2d4ddd 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ids.c > @@ -208,7 +208,7 @@ static int amdgpu_vmid_grab_idle(struct amdgpu_vm *vm, > if (ring->vmid_wait && !dma_fence_is_signaled(ring->vmid_wait)) > return amdgpu_sync_fence(sync, ring->vmid_wait); > > - fences = kmalloc_array(sizeof(void *), id_mgr->num_ids, GFP_KERNEL); > + fences = kmalloc_array(sizeof(void *), id_mgr->num_ids, GFP_ATOMIC); > if (!fences) > return -ENOMEM; > > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c > index 8ea6c49529e7..af22b526cec9 100644 > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c > @@ -160,7 +160,7 @@ int amdgpu_sync_fence(struct amdgpu_sync *sync, struct dma_fence *f) > if (amdgpu_sync_add_later(sync, f)) > return 0; > > - e = kmem_cache_alloc(amdgpu_sync_slab, GFP_KERNEL); > + e = kmem_cache_alloc(amdgpu_sync_slab, GFP_ATOMIC); > if (!e) > return -ENOMEM; > > -- > 2.27.0 > -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch