From patchwork Mon Oct 17 09:37:19 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Zhao Liu X-Patchwork-Id: 13008424 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 1F5EFC4332F for ; Mon, 17 Oct 2022 09:32:53 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 880E310ED13; Mon, 17 Oct 2022 09:32:50 +0000 (UTC) Received: from mga17.intel.com (mga17.intel.com [192.55.52.151]) by gabe.freedesktop.org (Postfix) with ESMTPS id 8E64110ED10; Mon, 17 Oct 2022 09:32:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1665999155; x=1697535155; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=h0hmpKyvdxb2sKw8lROgYrffCQobTfXddN7YtzQHU7M=; b=Ul4mgQ2PEWvaEHTyCXo+CpuOqncgpmy7bqoqyJLIaDvc0LS0uGxTBa7q xGSfbEPWNDAcbn1EEklVi0+OMzGQrUCwC0UJsMs2Y3UJXHXkmcmWjbf+3 q4h6zIyS//A0GM0phFQyG5AK8OTNT+c2epftNrFUT3LZX7miEC78ZOl8P kEIDverLDm6dOPMNvmufC2NmtxTFfT+m8RjLr0K2qUO+960SQ2KpFAfc3 KFJMkB8dudpBdwUaa/MAiNouKZvB0bJAT3yCKYL03HjtWraAlISk/hzER tRzANd8yFzjNhkAu2ReA1klGptaBniNjOwGSElWB7WE4V+sg34MFboUHz Q==; X-IronPort-AV: E=McAfee;i="6500,9779,10502"; a="286142624" X-IronPort-AV: E=Sophos;i="5.95,191,1661842800"; d="scan'208";a="286142624" Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga107.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 17 Oct 2022 02:32:35 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=McAfee;i="6500,9779,10502"; a="717431242" X-IronPort-AV: E=Sophos;i="5.95,191,1661842800"; d="scan'208";a="717431242" Received: from liuzhao-optiplex-7080.sh.intel.com ([10.239.160.132]) by FMSMGA003.fm.intel.com with ESMTP; 17 Oct 2022 02:32:31 -0700 From: Zhao Liu To: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Tvrtko Ursulin , David Airlie , Daniel Vetter , Matthew Auld , =?utf-8?q?Thomas_Hellstr=C3=B6m?= , Nirmoy Das , Maarten Lankhorst , Chris Wilson , =?utf-8?q?Christian_K=C3=B6nig?= , intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org Date: Mon, 17 Oct 2022 17:37:19 +0800 Message-Id: <20221017093726.2070674-4-zhao1.liu@linux.intel.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20221017093726.2070674-1-zhao1.liu@linux.intel.com> References: <20221017093726.2070674-1-zhao1.liu@linux.intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH 3/9] drm/i915: Use kmap_local_page() in gem/i915_gem_shmem.c X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Fabio M . De Francesco" , Ira Weiny , Zhao Liu , Zhenyu Wang Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" From: Zhao Liu The use of kmap_atomic() is being deprecated in favor of kmap_local_page()[1]. The main difference between atomic and local mappings is that local mappings doesn't disable page faults or preemption. In drm/i915/gem/i915_gem_shmem.c, the function shmem_pwrite() need to disable pagefault to eliminate the potential recursion fault[2]. But here __copy_from_user_inatomic() doesn't need to disable preemption and local mapping is valid for sched in/out. So it can use kmap_local_page() / kunmap_local() with pagefault_disable() / pagefault_enable() to replace atomic mapping. [1]: https://lore.kernel.org/all/20220813220034.806698-1-ira.weiny@intel.com [2]: https://patchwork.freedesktop.org/patch/295840/ Suggested-by: Ira Weiny Signed-off-by: Zhao Liu Reviewed-by: Ira Weiny Reviewed-by: Fabio M. De Francesco --- Suggested by credits: Ira: Referred to his suggestions about keeping pagefault_disable(). --- drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c index f42ca1179f37..e279a3e30c02 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c @@ -472,11 +472,13 @@ shmem_pwrite(struct drm_i915_gem_object *obj, if (err < 0) return err; - vaddr = kmap_atomic(page); + vaddr = kmap_local_page(page); + pagefault_disable(); unwritten = __copy_from_user_inatomic(vaddr + pg, user_data, len); - kunmap_atomic(vaddr); + pagefault_enable(); + kunmap_local(vaddr); err = aops->write_end(obj->base.filp, mapping, offset, len, len - unwritten, page, data);