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 47061CD4F3C for ; Wed, 20 May 2026 13:11:18 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id A39E310F06B; Wed, 20 May 2026 13:11:17 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (1024-bit key; unprotected) header.d=collabora.com header.i=igor.torrente@collabora.com header.b="i5FoT1Et"; dkim-atps=neutral Received: from sender4-pp-f112.zoho.com (sender4-pp-f112.zoho.com [136.143.188.112]) by gabe.freedesktop.org (Postfix) with ESMTPS id 6F1F510EC24 for ; Wed, 20 May 2026 13:11:16 +0000 (UTC) ARC-Seal: i=1; a=rsa-sha256; t=1779282670; cv=none; d=zohomail.com; s=zohoarc; b=h1A6Ce2M6EN2kc7ddYgHZvZ2kV4zvuk6c/Ej30YjJ05XfA2ra8yAD1svBWSpkgNES50zZiOTcxIHucqcnHbdqOtzSEhKIrjNi1Qw73uf75kjB0/8TgmVoEDUNPjRTq2fBDh1E1zEUrkF6pdX+bNagWn3xq/AG1BWmRAueV+HpbM= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=zohomail.com; s=zohoarc; t=1779282670; h=Content-Type:Content-Transfer-Encoding:Cc:Cc:Date:Date:From:From:In-Reply-To:MIME-Version:Message-ID:References:Subject:Subject:To:To:Message-Id:Reply-To; bh=IjZN7baVUkp//dQnaQw24mVQpih2pOULAojZG2gp0Fo=; b=SMKa67Ad+M3ejKVjzlB07Vr/dXAotzopnF9aGNKocu3HKCu0snvb37fjKDVsy/bPhE9TQDwNzlkp/Koag6wpfQhbR/66o5TmFlEPCMPvn7y2Kt50/OT4YMep9Y/4WMNbCnFbndwJ5kiCdnZz9THt0joTGFXfCLrkEtLzfJTl5fQ= ARC-Authentication-Results: i=1; mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=igor.torrente@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1779282670; s=zohomail; d=collabora.com; i=igor.torrente@collabora.com; h=Message-ID:Date:Date:MIME-Version:Subject:Subject:To:To:Cc:Cc:References:From:From:In-Reply-To:Content-Type:Content-Transfer-Encoding:Message-Id:Reply-To; bh=IjZN7baVUkp//dQnaQw24mVQpih2pOULAojZG2gp0Fo=; b=i5FoT1EtPfvjXFHCzphk8xuo3GfMtbtQml9yUO5aavwMBi3GrPmaEjF/FABRc3W/ UTR0EALQxg9Z5AqbPJZn5D3I+1fyuDbxhIci36XKxAKehOaR61EpzUoacy3jlp8wq+9 u4pyqovSgJ9/Z2Me/fm85JwHN6laJMSaNTiQA7Co= Received: by mx.zohomail.com with SMTPS id 1779282668370237.5626986578659; Wed, 20 May 2026 06:11:08 -0700 (PDT) Message-ID: Date: Wed, 20 May 2026 10:11:03 -0300 MIME-Version: 1.0 User-Agent: Betterbird (Linux) Subject: Re: [PATCH v3 5/6] drm/gem-shmem: Track folio accessed/dirty status in mmap To: Thomas Zimmermann , boris.brezillon@collabora.com, loic.molinari@collabora.com, willy@infradead.org, frank.binns@imgtec.com, matt.coster@imgtec.com, maarten.lankhorst@linux.intel.com, mripard@kernel.org, airlied@gmail.com, simona@ffwll.ch Cc: dri-devel@lists.freedesktop.org, linux-mm@kvack.org References: <20260209133241.238813-1-tzimmermann@suse.de> <20260209133241.238813-6-tzimmermann@suse.de> Content-Language: en-US From: Igor Torrente In-Reply-To: <20260209133241.238813-6-tzimmermann@suse.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-ZohoMailClient: External 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: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" On 2/9/26 10:27, Thomas Zimmermann wrote: > Invoke folio_mark_accessed() in mmap page faults to add the folio to > the memory manager's LRU list. Userspace invokes mmap to get the memory > for software rendering. Compositors do the same when creating the final > on-screen image, so keeping the pages in LRU makes sense. Avoids paging > out graphics buffers when under memory pressure. > > In pfn_mkwrite, further invoke the folio_mark_dirty() to add the folio > for writeback should the underlying file be paged out from system memory. > This rarely happens in practice, yet it would corrupt the buffer content. > > This has little effect on a system's hardware-accelerated rendering, which > only mmaps for an initial setup of textures, meshes, shaders, etc. > > v3: > - rewrite for VM_PFNMAP > v2: > - adapt to changes in drm_gem_shmem_try_mmap_pmd() > > Signed-off-by: Thomas Zimmermann > Reviewed-by: Boris Brezillon Hi Thomas, I have and Radxa ROCK 5B+ with Mali-G610 GPU and I'm developing the VDRM (native context) driver for panthor.ko. Recently I update my kernel from 7.0 to the 7.1-rc3, and qemu started freezing with KVM error below when running any graphical application with Venus or Panthor VDRM. For some reason Virgl is not affected. ``` error: kvm run failed Bad address PC=0000ffffb4a86d70 X00=0000ffffb4be5000 X01=0000ffffb2279bb0 X02=0000000000000600 X03=0000ffffb4be5000 X04=0000ffffb227a1b0 X05=0000ffffb4be5600 X06=0000000000000001 X07=0000aaaaf384fd80 X08=dcc58d0daf897753 X09=0000000000000002 X10=0000ffffb4b96758 X11=000000002533f84b X12=0000000000001060 X13=0000000000000000 X14=0000000000000000 X15=0000000000000010 X16=0000ffffb3880128 X17=0000ffffb4a86c80 X18=0000000000000000 X19=0000aaaaf384f8a0 X20=0000aaaaf37cec80 X21=0000aaaaf37c7210 X22=0000aaaaf37c9550 X23=0000aaaaf37c74e0 X24=0000ffffb3b47fc8 X25=0000ffffb3b47fc8 X26=0000ffffb3b43c78 X27=0000aaaaf37e1840 X28=0000aaaaf37cee50 X29=0000ffffecbf1a60 X30=0000ffffb364b530  SP=0000ffffecbf1a60 PSTATE=0000000020001000 --C- EL0t ``` After bisecting I reach to your commit. ``` 28e3918179aa75cfd4490b3b0281496ed91d829a  drm/gem-shmem: Track folio accessed/dirty status in mmap ``` It still reproducible in the 7.1-rc4 (ab5fce87a778). Appling the following patch (Boris suggestion) fixes the issue for me. ``` diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c index 545933c7f712..1e036f69c1ce 100644 --- a/drivers/gpu/drm/drm_gem_shmem_helper.c +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c @@ -696,7 +696,7 @@ const struct vm_operations_struct drm_gem_shmem_vm_ops = {  #endif         .open = drm_gem_shmem_vm_open,         .close = drm_gem_shmem_vm_close, -       .pfn_mkwrite = drm_gem_shmem_pfn_mkwrite, +//     .pfn_mkwrite = drm_gem_shmem_pfn_mkwrite,  };  EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops); ``` I'm not familiar with the drm_gem, code so I don't any more insightful information to share.  But hopefully we can find a better fix for this. BR, Igor Torrente > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 20 ++++++++++++++++++++ > 1 file changed, 20 insertions(+) > > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm_gem_shmem_helper.c > index c3a054899ba3..0c86ad40a049 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -598,6 +598,9 @@ static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) > if (ret != VM_FAULT_NOPAGE) > ret = vmf_insert_pfn(vma, vmf->address, pfn); > > + if (likely(!(ret & VM_FAULT_ERROR))) > + folio_mark_accessed(folio); > + > out: > dma_resv_unlock(obj->resv); > > @@ -638,10 +641,27 @@ static void drm_gem_shmem_vm_close(struct vm_area_struct *vma) > drm_gem_vm_close(vma); > } > > +static vm_fault_t drm_gem_shmem_pfn_mkwrite(struct vm_fault *vmf) > +{ > + struct vm_area_struct *vma = vmf->vma; > + struct drm_gem_object *obj = vma->vm_private_data; > + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); > + pgoff_t page_offset = vmf->pgoff - vma->vm_pgoff; /* page offset within VMA */ > + struct page *page = shmem->pages[page_offset]; > + struct folio *folio = page_folio(page); > + > + file_update_time(vma->vm_file); > + > + folio_mark_dirty(folio); > + > + return 0; > +} > + > const struct vm_operations_struct drm_gem_shmem_vm_ops = { > .fault = drm_gem_shmem_fault, > .open = drm_gem_shmem_vm_open, > .close = drm_gem_shmem_vm_close, > + .pfn_mkwrite = drm_gem_shmem_pfn_mkwrite, > }; > EXPORT_SYMBOL_GPL(drm_gem_shmem_vm_ops); >