From patchwork Thu Apr 6 16:06:30 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Dmitry Osipenko X-Patchwork-Id: 91090 Received: from vger.kernel.org ([23.128.96.18]) by www.linuxtv.org with esmtp (Exim 4.92) (envelope-from ) id 1pkS8t-00DkVS-9x; Thu, 06 Apr 2023 16:07:19 +0000 Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239880AbjDFQHR (ORCPT + 1 other); Thu, 6 Apr 2023 12:07:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45618 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239844AbjDFQHQ (ORCPT ); Thu, 6 Apr 2023 12:07:16 -0400 Received: from madras.collabora.co.uk (madras.collabora.co.uk [46.235.227.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6E8819EE4; Thu, 6 Apr 2023 09:07:00 -0700 (PDT) Received: from workpc.. (109-252-119-170.nat.spd-mgts.ru [109.252.119.170]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) (Authenticated sender: dmitry.osipenko) by madras.collabora.co.uk (Postfix) with ESMTPSA id D662966031C6; Thu, 6 Apr 2023 17:06:56 +0100 (BST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=collabora.com; s=mail; t=1680797218; bh=Hk90072+fNtMk6bzJlUk3vMa94X4jOPr38sjSqJGC68=; h=From:To:Cc:Subject:Date:From; b=TH08idU5sasycPk66wdrwrZWcxg/7Zyy0vnU/rvtWLMSQCnWqR9sufNIHDMt1NqCI kaSdKDy4CLUXpyyJnsgkHHbnJpWjoG1seTkqmqiaw3TtIb/jzh8dN59CvqgSDAWuXd dLiGDkamMv2gWwTj0Gwrv/dJq65b4oTMWtbrdQ/+ssBKv79x8rDhe84Wv/HegpkjtO rv0vjx5/VXtvIXjIGo1VEl/oZaUrK9794lnBIJLMrt0FHAV65ixcCun5Za6l+nL+jH wWz94cfPKOR7sTmMBaomC3wlLst5l5yTJonZyYboDwfPi9jpS+fmiMXB+64tbt8c+J 0g82VUu1eSmvw== From: Dmitry Osipenko To: Sumit Semwal , =?utf-8?q?Christian_K=C3=B6nig?= , Benjamin Gaignard , Liam Mark , Brian Starkey , John Stultz , Gerd Hoffmann , Daniel Vetter , Jani Nikula , Arnd Bergmann , Greg Kroah-Hartman , Thomas Zimmermann , Tomi Valkeinen , Thierry Reding , Tomasz Figa , Marek Szyprowski , Mauro Carvalho Chehab , Srinivas Kandagatla , Amol Maheshwari , Emil Velikov Cc: linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, intel-gfx@lists.freedesktop.org, linux-tegra@vger.kernel.org, linux-arm-msm@vger.kernel.org, kernel@collabora.com Subject: [PATCH v2 0/7] Move dma-buf mmap() reservation locking down to exporters Date: Thu, 6 Apr 2023 19:06:30 +0300 Message-Id: <20230406160637.541702-1-dmitry.osipenko@collabora.com> X-Mailer: git-send-email 2.39.2 MIME-Version: 1.0 X-Spam-Status: No, score=-0.2 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org X-LSpam-Score: -2.5 (--) X-LSpam-Report: No, score=-2.5 required=5.0 tests=BAYES_00=-1.9,DKIM_SIGNED=0.1,DKIM_VALID=-0.1,DKIM_VALID_AU=-0.1,HEADER_FROM_DIFFERENT_DOMAINS=0.5,MAILING_LIST_MULTI=-1 autolearn=ham autolearn_force=no This patchset makes dma-buf exporters responisble for taking care of the reservation lock. I also included patch that moves drm-shmem to use reservation lock, to let CI test the whole set. I'm going to take all the patches via the drm-misc tree, please give an ack. Previous policy stated that dma-buf core takes the lock around mmap() callback. Which meant that both importers and exporters shouldn't touch the reservation lock in the mmap() code path. This worked well until Intel-CI found a deadlock problem in a case of self-imported dma-buf [1]. The problem happens when userpace mmaps a self-imported dma-buf, i.e. mmaps the dma-buf FD. DRM core treats self-imported dma-bufs as own GEMs [2]. There is no way to differentiate a prime GEM from a normal GEM for drm-shmem in drm_gem_shmem_mmap(), which resulted in a deadlock problem for drm-shmem mmap() code path once it's switched to use reservation lock. It was difficult to fix the drm-shmem problem without adjusting dma-buf locking policy. In parctice not much changed from importers perspective because previosly dma-buf was taking the lock in between of importers and exporters. Now this lock is shifted down to exporters. [1] https://intel-gfx-ci.01.org/tree/drm-tip/Patchwork_114671v2/shard-snb5/igt@prime_vgem@sync@rcs0.html [2] https://elixir.bootlin.com/linux/v6.3-rc4/source/drivers/gpu/drm/drm_prime.c#L924 Changelog: v2: - Added ack from Christian König to the DRM patch. - Dropped "fixes" tag from the patches, like was requested by Christian König. The patches don't actually need a backport and merely improve the locking policy. - Dropped "reverts" from the patch titles to prevent them from auto-backporting by the stable bot based on the title. - Added r-b from Emil Velikov and placed the drm_WARN in the drm-shmem patch like he suggested in a comment to v1. - Corrected drm-shmem patch dma_resv_lock(obj->resv) inconsistently used with dma_resv_unlock(shmem->base.resv). Now shmem->base.resv variant is used for all locks/unlocks. Dmitry Osipenko (7): media: videobuf2: Don't assert held reservation lock for dma-buf mmapping dma-buf/heaps: Don't assert held reservation lock for dma-buf mmapping udmabuf: Don't assert held reservation lock for dma-buf mmapping fastrpc: Don't assert held reservation lock for dma-buf mmapping drm: Don't assert held reservation lock for dma-buf mmapping dma-buf: Change locking policy for mmap() drm/shmem-helper: Switch to reservation lock drivers/dma-buf/dma-buf.c | 17 +- drivers/dma-buf/heaps/cma_heap.c | 3 - drivers/dma-buf/heaps/system_heap.c | 3 - drivers/dma-buf/udmabuf.c | 2 - drivers/gpu/drm/drm_gem_shmem_helper.c | 208 ++++++++---------- drivers/gpu/drm/drm_prime.c | 2 - drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c | 2 - drivers/gpu/drm/lima/lima_gem.c | 8 +- drivers/gpu/drm/omapdrm/omap_gem_dmabuf.c | 2 - drivers/gpu/drm/panfrost/panfrost_drv.c | 7 +- .../gpu/drm/panfrost/panfrost_gem_shrinker.c | 6 +- drivers/gpu/drm/panfrost/panfrost_mmu.c | 19 +- drivers/gpu/drm/tegra/gem.c | 2 - .../common/videobuf2/videobuf2-dma-contig.c | 3 - .../media/common/videobuf2/videobuf2-dma-sg.c | 3 - .../common/videobuf2/videobuf2-vmalloc.c | 3 - drivers/misc/fastrpc.c | 3 - include/drm/drm_gem_shmem_helper.h | 14 +- 18 files changed, 117 insertions(+), 190 deletions(-)