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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT 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 2BFE2C10F05 for ; Wed, 20 Mar 2019 15:23:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 082E4218A1 for ; Wed, 20 Mar 2019 15:23:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727572AbfCTPXr (ORCPT ); Wed, 20 Mar 2019 11:23:47 -0400 Received: from ex13-edg-ou-002.vmware.com ([208.91.0.190]:12321 "EHLO EX13-EDG-OU-002.vmware.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726595AbfCTPXq (ORCPT ); Wed, 20 Mar 2019 11:23:46 -0400 Received: from sc9-mailhost3.vmware.com (10.113.161.73) by EX13-EDG-OU-002.vmware.com (10.113.208.156) with Microsoft SMTP Server id 15.0.1156.6; Wed, 20 Mar 2019 08:23:40 -0700 Received: from fedoratest.localdomain (unknown [10.30.24.114]) by sc9-mailhost3.vmware.com (Postfix) with ESMTP id D58B94199D; Wed, 20 Mar 2019 08:23:41 -0700 (PDT) From: Thomas Hellstrom To: CC: , Thomas Hellstrom , Andrew Morton , Matthew Wilcox , Will Deacon , Peter Zijlstra , Rik van Riel , Minchan Kim , Michal Hocko , Huang Ying , Souptick Joarder , =?UTF-8?q?J=C3=A9r=C3=B4me=20Glisse?= , , Subject: [RFC PATCH 1/3] mm: Allow the [page|pfn]_mkwrite callbacks to drop the mmap_sem Date: Wed, 20 Mar 2019 16:23:13 +0100 Message-ID: <20190320152315.82758-2-thellstrom@vmware.com> X-Mailer: git-send-email 2.19.0.rc1 In-Reply-To: <20190320152315.82758-1-thellstrom@vmware.com> References: <20190320152315.82758-1-thellstrom@vmware.com> MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8bit Received-SPF: None (EX13-EDG-OU-002.vmware.com: thellstrom@vmware.com does not designate permitted sender hosts) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Driver fault callbacks are allowed to drop the mmap_sem when expecting long hardware waits to avoid blocking other mm users. Allow the mkwrite callbacks to do the same by returning early on VM_FAULT_RETRY. In particular we want to be able to drop the mmap_sem when waiting for a reservation object lock on a GPU buffer object. These locks may be held while waiting for the GPU. Cc: Andrew Morton Cc: Matthew Wilcox Cc: Will Deacon Cc: Peter Zijlstra Cc: Rik van Riel Cc: Minchan Kim Cc: Michal Hocko Cc: Huang Ying Cc: Souptick Joarder Cc: "Jérôme Glisse" Cc: linux-mm@kvack.org Cc: linux-kernel@vger.kernel.org Signed-off-by: Thomas Hellstrom --- mm/memory.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/mm/memory.c b/mm/memory.c index a52663c0612d..dcd80313cf10 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -2144,7 +2144,7 @@ static vm_fault_t do_page_mkwrite(struct vm_fault *vmf) ret = vmf->vma->vm_ops->page_mkwrite(vmf); /* Restore original flags so that caller is not surprised */ vmf->flags = old_flags; - if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE))) + if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_RETRY | VM_FAULT_NOPAGE))) return ret; if (unlikely(!(ret & VM_FAULT_LOCKED))) { lock_page(page); @@ -2419,7 +2419,7 @@ static vm_fault_t wp_pfn_shared(struct vm_fault *vmf) pte_unmap_unlock(vmf->pte, vmf->ptl); vmf->flags |= FAULT_FLAG_MKWRITE; ret = vma->vm_ops->pfn_mkwrite(vmf); - if (ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)) + if (ret & (VM_FAULT_ERROR | VM_FAULT_RETRY | VM_FAULT_NOPAGE)) return ret; return finish_mkwrite_fault(vmf); } @@ -2440,7 +2440,8 @@ static vm_fault_t wp_page_shared(struct vm_fault *vmf) pte_unmap_unlock(vmf->pte, vmf->ptl); tmp = do_page_mkwrite(vmf); if (unlikely(!tmp || (tmp & - (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { + (VM_FAULT_ERROR | VM_FAULT_RETRY | + VM_FAULT_NOPAGE)))) { put_page(vmf->page); return tmp; } @@ -3472,7 +3473,8 @@ static vm_fault_t do_shared_fault(struct vm_fault *vmf) unlock_page(vmf->page); tmp = do_page_mkwrite(vmf); if (unlikely(!tmp || - (tmp & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))) { + (tmp & (VM_FAULT_ERROR | VM_FAULT_RETRY | + VM_FAULT_NOPAGE)))) { put_page(vmf->page); return tmp; } -- 2.19.0.rc1