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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6D9ABD116F5 for ; Mon, 1 Dec 2025 08:17:00 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id B3CE06B0022; Mon, 1 Dec 2025 03:16:59 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id B14126B0024; Mon, 1 Dec 2025 03:16:59 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id A51276B0026; Mon, 1 Dec 2025 03:16:59 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 945A96B0022 for ; Mon, 1 Dec 2025 03:16:59 -0500 (EST) Received: from smtpin02.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay04.hostedemail.com (Postfix) with ESMTP id 407B51A0842 for ; Mon, 1 Dec 2025 08:16:59 +0000 (UTC) X-FDA: 84170196558.02.D329387 Received: from bali.collaboradmins.com (bali.collaboradmins.com [148.251.105.195]) by imf06.hostedemail.com (Postfix) with ESMTP id 4013A180016 for ; Mon, 1 Dec 2025 08:16:57 +0000 (UTC) Authentication-Results: imf06.hostedemail.com; dkim=pass header.d=collabora.com header.s=mail header.b=MtQNiUA8; spf=pass (imf06.hostedemail.com: domain of boris.brezillon@collabora.com designates 148.251.105.195 as permitted sender) smtp.mailfrom=boris.brezillon@collabora.com; dmarc=pass (policy=none) header.from=collabora.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1764577017; h=from:from:sender: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:dkim-signature; bh=YQ0VZPoDm0JewNcCiq9HLkGqzWBIpasi/lSax/oKY04=; b=CwXmhwF2fHQG9vqL79PduGukZJO0/ihYJ/MCV013cCY0fwthph7/81lMHoTc7WJlEre3cy odpmeGJ5CoRK3zT9wnaWYKEc/rQc2u1ISdd0Hu2rEjoj7hM/AUux7xpxPz4hYbUMhNMueC go16mXbwm2tdG8bL2uHDc6ZevEuolbM= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1764577017; a=rsa-sha256; cv=none; b=1jC39OjGvv3PiPalaK5KARsw+qW6J7rFYsCVGxHiee8HIUibbmW8ZYWiBvjYelvnPKzxRE 6QFMPXuM4szGEPFL6uihG0bqZFWp57RVPfWN/4Sr7VFqBdrYonQOED5W+kb/cmqGmlWY4B 2Wrg0rQXx0htRKLHSr5XjeGSuhra6r8= ARC-Authentication-Results: i=1; imf06.hostedemail.com; dkim=pass header.d=collabora.com header.s=mail header.b=MtQNiUA8; spf=pass (imf06.hostedemail.com: domain of boris.brezillon@collabora.com designates 148.251.105.195 as permitted sender) smtp.mailfrom=boris.brezillon@collabora.com; dmarc=pass (policy=none) header.from=collabora.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1764577014; bh=SjCMyB1dHNwtgPTS0MoHLJhuhnjVA2MdD0tj6aAiy7Q=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=MtQNiUA8jUaVwIUGbuaTBXQWC/AgCctwBHVMPb+164YHYlYfjkrYFBJELoRP0VqGb P9DYysHwyY9kNkN4LfOU3AU5gV+OjAkHy48NAyqKLDB8GeZLuhfjPlr524yI4a4YzQ VvkTxUKOq+PtulTUbIbaODh1Xj+fWtWz3HKq+LS9iTVwP6xLmecWck7pwCi9gQY0uJ PXBtYQTRV2aQxBC+xkYBfdJZjqFfX0pf0/lyTxNAzTFkL6Dy0RMJxjTzXr59VDelRL 5V6fNUFWH+w1H0gQT+gSiwBWn38MemyT2zTpwxcnhY2dHLO3SE5/VWksC+H8btMcPI nfEFt6sQabtYw== Received: from fedora (unknown [IPv6:2a01:e0a:2c:6930:d919:a6e:5ea1:8a9f]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (prime256v1) server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: bbrezillon) by bali.collaboradmins.com (Postfix) with ESMTPSA id 9CCE617E126B; Mon, 1 Dec 2025 09:16:53 +0100 (CET) Date: Mon, 1 Dec 2025 09:16:50 +0100 From: Boris Brezillon To: =?UTF-8?B?TG/Dr2M=?= Molinari Cc: Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , Rob Herring , Steven Price , Liviu Dudau , Melissa Wen , =?UTF-8?B?TWHDrXJh?= Canal , Hugh Dickins , Baolin Wang , Andrew Morton , Al Viro , =?UTF-8?B?TWlrb8WCYWo=?= Wasiak , Christian Brauner , Nitin Gote , Andi Shyti , Jonathan Corbet , Christopher Healy , Matthew Wilcox , Bagas Sanjaya , linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, intel-gfx@lists.freedesktop.org, linux-mm@kvack.org, linux-doc@vger.kernel.org, kernel@collabora.com Subject: Re: [PATCH v10 02/10] drm/shmem-helper: Map huge pages in fault handler Message-ID: <20251201091650.4c45e494@fedora> In-Reply-To: <20251128185252.3092-3-loic.molinari@collabora.com> References: <20251128185252.3092-1-loic.molinari@collabora.com> <20251128185252.3092-3-loic.molinari@collabora.com> Organization: Collabora X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspam-User: X-Stat-Signature: 8tanp4i49j3braxejr1bt48pdnt8hzsg X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 4013A180016 X-HE-Tag: 1764577017-435717 X-HE-Meta: U2FsdGVkX18B7vgbWytVBgPX39iO+J80NbYCwUjAO0WzvnOBPccS1qYdh3UCWN4Oc09xejJrRwLxSO4jxZyHapvy9JW3ne38kQQAf2FQZGa2zUQ0qyW1tmCLj1o/zJ+ocQU31wfNoIrv9vusrgXU/l9/VHyFW8Nq5BqZz61rZ44zYHrvOjeH5xllppS1ypoTKQ+NzOB3/LPzYb2dDyt2B1jGSNgdEMscjGEfVjGK8vW1dS2UGGEq6GNUFBCUlFcSi4qRqKuRnJdpX9IHPecYA0k/XGgBRE1Yl42qLPrA2QyE5RB9Pa9hhrqY/YQCz3k5vZxKD2mz4EraxFs+tsqQoqfVnx66XQapmhV7qeVPSaSKa2NztWKFleek9vjjDtJkKgOQ7rqsS/eQUBRP9eDfyEiqNgYAjsNjtuCRB3fm/d0MSGYxg8Mzh0u/ETE+tlqdGMb8PpOA4+T71u5I91skha75A3PkNYeK1u5ExpfrkD4ogNTc3FpICIwF1XqoJLHed+5Ao79cYsDUaig5yhY0hdoWTUxRr/v+MOMpmQNWSoPMJ2OqefBtMbpugNqKuMW/0q20fASOPqLjVV0l8n/4aPyeee6leHkvEhbC03XDytqHcauv8vySr9+VUHjC59iujdhnr/mkCPdPfX3xfBUbTCzV7nH5FdQJGDlwAyUqyiBl40pVdemLAcVfFrlHO2kbbAAa1aJBRA4DXtmvCoFQOnSRABSzf1VMkKBcYQw4jSSZNLtDQK1j6/whNoZvkwu50oUfrljXFahkrtmg1FZMTiY/ZcyP/fo9ilFdAtG7Vn4AQSDfTn0icbAWndXFvCuFmR1UiqBK4o2VMAGVYjERql8Hakc+xbyNLK5DLMRnmqEeZVDjgbheVbrqdzEIFmNP9TH6Ve20tngUWP74etDjIaMa1D0/lOsBTyrqTaNSPVxW0hGXrf119HJTohJECYH47VJgrnJyZn2ahK9l6YH +00hgNyT J0N7SNhfWax2bGrho5oX/2PQMBKc6UAbRT4wkVK8fuEG0xkSJkp/ArHPz1SRGffhD4n14D19AL2cFMT80CEMKwxG6YzZ8wV+eZJDhQVAR2kBEX4gbMvPCqN6kQdW6KBcLbj3Er+FLrLoDY3gms/gsrp5okVXBeG/F1TO5AqC9eF/t5N4rEfHUr02LlZNiQ0uJzvcWvAdVaDFOZrUbyCaAqjLQLYSMJQihszwElAwssCzdD2G1mQ70PLRQXEaOu8w73/osYn9zWo85gDKXdN9qx8RnDCT11GAZ6OsRZpUC4rg3hsTExPMw7uTGhRjj7QU9bOSxFdM5UKA19gDIcw4Iufi9hJM8y7+/hXNafk6DbOzncOjTqundTM3f1A== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 28 Nov 2025 19:52:44 +0100 Lo=C3=AFc Molinari wrote: > Attempt a PMD sized PFN insertion into the VMA if the faulty address > of the fault handler is part of a huge page. >=20 > On builds with CONFIG_TRANSPARENT_HUGEPAGE enabled, if the mmap() user > address is PMD size aligned, if the GEM object is backed by shmem > buffers on mountpoints setting the 'huge=3D' option and if the shmem > backing store manages to allocate a huge folio, CPU mapping would then > benefit from significantly increased memcpy() performance. When these > conditions are met on a system with 2 MiB huge pages, an aligned copy > of 2 MiB would raise a single page fault instead of 4096. >=20 > v4: > - implement map_pages instead of huge_fault >=20 > v6: > - get rid of map_pages handler for now (keep it for another series > along with arm64 contpte support) >=20 > Signed-off-by: Lo=C3=AFc Molinari > --- > drivers/gpu/drm/drm_gem_shmem_helper.c | 55 +++++++++++++++++++++----- > 1 file changed, 46 insertions(+), 9 deletions(-) >=20 > diff --git a/drivers/gpu/drm/drm_gem_shmem_helper.c b/drivers/gpu/drm/drm= _gem_shmem_helper.c > index be89be1c804c..81f4ac7cb8f6 100644 > --- a/drivers/gpu/drm/drm_gem_shmem_helper.c > +++ b/drivers/gpu/drm/drm_gem_shmem_helper.c > @@ -567,31 +567,68 @@ int drm_gem_shmem_dumb_create(struct drm_file *file= , struct drm_device *dev, > } > EXPORT_SYMBOL_GPL(drm_gem_shmem_dumb_create); > =20 > +static bool drm_gem_shmem_fault_is_valid(struct drm_gem_object *obj, > + pgoff_t pgoff) AFAICT, extracting the fault_is_valid() logic into a helper is orthogonal to the huge_page mapping stuff, and I don't see it being used in the rest of the series (I guess it was when you were introducing support for map_pages()). Maybe this should be done in a separate patch, or postponed until there's a second place checking for fault validity, dunno. > +{ > + struct drm_gem_shmem_object *shmem =3D to_drm_gem_shmem_obj(obj); > + > + if (drm_WARN_ON_ONCE(obj->dev, !shmem->pages) || > + pgoff >=3D (obj->size >> PAGE_SHIFT) || > + shmem->madv < 0) > + return false; > + > + return true; > +} > + > +static bool drm_gem_shmem_map_pmd(struct vm_fault *vmf, unsigned long ad= dr, > + struct page *page) nit: could we name that one drm_gem_shmem_try_map_pmd()? With my two nits addressed, the patch is Reviewed-by: Boris Brezillon > +{ > +#ifdef CONFIG_ARCH_SUPPORTS_PMD_PFNMAP > + unsigned long pfn =3D page_to_pfn(page); > + unsigned long paddr =3D pfn << PAGE_SHIFT; > + bool aligned =3D (addr & ~PMD_MASK) =3D=3D (paddr & ~PMD_MASK); > + > + if (aligned && > + pmd_none(*vmf->pmd) && > + folio_test_pmd_mappable(page_folio(page))) { > + pfn &=3D PMD_MASK >> PAGE_SHIFT; > + if (vmf_insert_pfn_pmd(vmf, pfn, false) =3D=3D VM_FAULT_NOPAGE) > + return true; > + } > +#endif > + > + return false; > +} > + > static vm_fault_t drm_gem_shmem_fault(struct vm_fault *vmf) > { > struct vm_area_struct *vma =3D vmf->vma; > struct drm_gem_object *obj =3D vma->vm_private_data; > struct drm_gem_shmem_object *shmem =3D to_drm_gem_shmem_obj(obj); > - loff_t num_pages =3D obj->size >> PAGE_SHIFT; > - vm_fault_t ret; > - struct page *page; > + struct page **pages =3D shmem->pages; > pgoff_t page_offset; > + unsigned long pfn; > + vm_fault_t ret; > =20 > /* Offset to faulty address in the VMA (without the fake offset). */ > page_offset =3D vmf->pgoff - vma->vm_pgoff; > =20 > dma_resv_lock(shmem->base.resv, NULL); > =20 > - if (page_offset >=3D num_pages || > - drm_WARN_ON_ONCE(obj->dev, !shmem->pages) || > - shmem->madv < 0) { > + if (unlikely(!drm_gem_shmem_fault_is_valid(obj, page_offset))) { > ret =3D VM_FAULT_SIGBUS; > - } else { > - page =3D shmem->pages[page_offset]; > + goto out; > + } > =20 > - ret =3D vmf_insert_pfn(vma, vmf->address, page_to_pfn(page)); > + if (drm_gem_shmem_map_pmd(vmf, vmf->address, pages[page_offset])) { > + ret =3D VM_FAULT_NOPAGE; > + goto out; > } > =20 > + pfn =3D page_to_pfn(pages[page_offset]); > + ret =3D vmf_insert_pfn(vma, vmf->address, pfn); > + > + out: > dma_resv_unlock(shmem->base.resv); > =20 > return ret;