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Violators will be prosecuted; Fri, 13 Apr 2018 10:59:45 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w3D9xjTL9175550; Fri, 13 Apr 2018 09:59:45 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 66E4C52043; Fri, 13 Apr 2018 09:50:40 +0100 (BST) Received: from [9.202.15.240] (unknown [9.202.15.240]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 88C8E52041; Fri, 13 Apr 2018 09:50:37 +0100 (BST) 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 Precedence: bulk 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.