From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754080AbeDMJ7x (ORCPT ); Fri, 13 Apr 2018 05:59:53 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:33692 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751847AbeDMJ7w (ORCPT ); Fri, 13 Apr 2018 05:59:52 -0400 Subject: Re: [PATCH] mm: vmalloc: Remove double execution of vunmap_page_range To: Chintan Pandya , vbabka@suse.cz, labbott@redhat.com, catalin.marinas@arm.com, hannes@cmpxchg.org, f.fainelli@gmail.com, xieyisheng1@huawei.com, ard.biesheuvel@linaro.org, richard.weiyang@gmail.com, byungchul.park@lge.com References: <1523611019-17679-1-git-send-email-cpandya@codeaurora.org> Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org From: Anshuman Khandual Date: Fri, 13 Apr 2018 15:29:41 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.5.1 MIME-Version: 1.0 In-Reply-To: <1523611019-17679-1-git-send-email-cpandya@codeaurora.org> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 18041309-0044-0000-0000-00000546DA24 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18041309-0045-0000-0000-0000288718F2 Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-04-13_05:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1011 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1804130093 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/13/2018 02:46 PM, Chintan Pandya wrote: > Unmap legs do call vunmap_page_range() irrespective of > debug_pagealloc_enabled() is enabled or not. So, remove > redundant check and optional vunmap_page_range() routines. vunmap_page_range() tears down the page table entries and does not really flush related TLB entries normally unless page alloc debug is enabled where it wants to make sure no stale mapping is still around for debug purpose. Deferring TLB flush improves performance. This patch will force TLB flush during each page table tear down and hence not desirable.