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=-7.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 B4000C433DF for ; Fri, 7 Aug 2020 06:23:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 89EFF221E5 for ; Fri, 7 Aug 2020 06:23:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781417; bh=7M0jg7yholAju8SOMhmmiV8eGyURQU75l//ZPH4NJrE=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=cWXo/gE1Z2/deSafNLiCorsMSjXcEHKUmGIiz2Pnm5oJxPYJtHBLlE8CH1RhrBHIA JbQlRwHaYYyloM5p+aMO0J1o7gAIloxG3I7yeXwyFZXhRX0RZFFlUu8Uz9cFXrD1YR oq7EaOHMsCF7alMutGCIFrY+uUjLhjeaV6rdyGWk= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726294AbgHGGXf (ORCPT ); Fri, 7 Aug 2020 02:23:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:60558 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725379AbgHGGXf (ORCPT ); Fri, 7 Aug 2020 02:23:35 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 8240F22CB3; Fri, 7 Aug 2020 06:23:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781414; bh=7M0jg7yholAju8SOMhmmiV8eGyURQU75l//ZPH4NJrE=; h=Date:From:To:Subject:In-Reply-To:From; b=RUmvebJM2Y1REtpnY/HVM2ZsMsg3zYJjBo7SDDw4eVr8vTrzVUxQ1Sa4WaT9gLg2E XT3ERrhYapRzTXH2XRT2cSprPzFG5m5SDQ8IWoZtcYEHo6tVkSKG3nIzbodQj5up5j wI11fUgO9TimBDCfDogA3d3Fubk9PCBJruoPXPp4= Date: Thu, 06 Aug 2020 23:23:34 -0700 From: Andrew Morton To: akpm@linux-foundation.org, linmiaohe@huawei.com, linux-mm@kvack.org, louhongxiang@huawei.com, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 112/163] mm: mmap: merge vma after call_mmap() if possible Message-ID: <20200807062334.ItecIkHkO%akpm@linux-foundation.org> In-Reply-To: <20200806231643.a2711a608dd0f18bff2caf2b@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Miaohe Lin Subject: mm: mmap: merge vma after call_mmap() if possible The vm_flags may be changed after call_mmap() because drivers may set some flags for their own purpose. As a result, we failed to merge the adjacent vma due to the different vm_flags as userspace can't pass in the same one. Try to merge vma after call_mmap() to fix this issue. Link: http://lkml.kernel.org/r/1594954065-23733-1-git-send-email-linmiaohe@huawei.com Signed-off-by: Hongxiang Lou Signed-off-by: Miaohe Lin Reviewed-by: Andrew Morton Signed-off-by: Andrew Morton --- mm/mmap.c | 22 +++++++++++++++++++++- 1 file changed, 21 insertions(+), 1 deletion(-) --- a/mm/mmap.c~mm-mmap-merge-vma-after-call_mmap-if-possible +++ a/mm/mmap.c @@ -1690,7 +1690,7 @@ unsigned long mmap_region(struct file *f struct list_head *uf) { struct mm_struct *mm = current->mm; - struct vm_area_struct *vma, *prev; + struct vm_area_struct *vma, *prev, *merge; int error; struct rb_node **rb_link, *rb_parent; unsigned long charged = 0; @@ -1774,6 +1774,25 @@ unsigned long mmap_region(struct file *f if (error) goto unmap_and_free_vma; + /* If vm_flags changed after call_mmap(), we should try merge vma again + * as we may succeed this time. + */ + if (unlikely(vm_flags != vma->vm_flags && prev)) { + merge = vma_merge(mm, prev, vma->vm_start, vma->vm_end, vma->vm_flags, + NULL, vma->vm_file, vma->vm_pgoff, NULL, NULL_VM_UFFD_CTX); + if (merge) { + fput(file); + vm_area_free(vma); + vma = merge; + /* Update vm_flags and possible addr to pick up the change. We don't + * warn here if addr changed as the vma is not linked by vma_link(). + */ + addr = vma->vm_start; + vm_flags = vma->vm_flags; + goto unmap_writable; + } + } + /* Can addr have changed?? * * Answer: Yes, several device drivers can do it in their @@ -1796,6 +1815,7 @@ unsigned long mmap_region(struct file *f vma_link(mm, vma, prev, rb_link, rb_parent); /* Once vma denies write, undo our temporary denial count */ if (file) { +unmap_writable: if (vm_flags & VM_SHARED) mapping_unmap_writable(file->f_mapping); if (vm_flags & VM_DENYWRITE) _