From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f199.google.com (mail-pf0-f199.google.com [209.85.192.199]) by kanga.kvack.org (Postfix) with ESMTP id 00D866B0033 for ; Wed, 25 Jan 2017 21:54:22 -0500 (EST) Received: by mail-pf0-f199.google.com with SMTP id 80so291224501pfy.2 for ; Wed, 25 Jan 2017 18:54:21 -0800 (PST) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com. [148.163.156.1]) by mx.google.com with ESMTPS id s5si25214295pgg.177.2017.01.25.18.54.20 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 25 Jan 2017 18:54:21 -0800 (PST) Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.20/8.16.0.20) with SMTP id v0Q2n26o111440 for ; Wed, 25 Jan 2017 21:54:20 -0500 Received: from e28smtp05.in.ibm.com (e28smtp05.in.ibm.com [125.16.236.5]) by mx0a-001b2d01.pphosted.com with ESMTP id 286xbry5jh-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Wed, 25 Jan 2017 21:54:20 -0500 Received: from localhost by e28smtp05.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 26 Jan 2017 08:24:16 +0530 Received: from d28relay10.in.ibm.com (d28relay10.in.ibm.com [9.184.220.161]) by d28dlp01.in.ibm.com (Postfix) with ESMTP id 2F0D7E0024 for ; Thu, 26 Jan 2017 08:25:29 +0530 (IST) Received: from d28av03.in.ibm.com (d28av03.in.ibm.com [9.184.220.65]) by d28relay10.in.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v0Q2rLYs26869978 for ; Thu, 26 Jan 2017 08:23:21 +0530 Received: from d28av03.in.ibm.com (localhost [127.0.0.1]) by d28av03.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id v0Q2sCHd011293 for ; Thu, 26 Jan 2017 08:24:13 +0530 Date: Wed, 25 Jan 2017 18:54:08 -0800 From: Srikar Dronamraju Subject: Re: [PATCH 01/12] uprobes: split THPs before trying replace them Reply-To: Srikar Dronamraju References: <20170124162824.91275-1-kirill.shutemov@linux.intel.com> <20170124162824.91275-2-kirill.shutemov@linux.intel.com> <20170124132849.73135e8c6e9572be00dbbe79@linux-foundation.org> <20170124222217.GB19920@node.shutemov.name> <20170125165522.GA11569@linux.vnet.ibm.com> <20170125183510.GB17286@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20170125183510.GB17286@cmpxchg.org> Message-Id: <20170126025408.GB11569@linux.vnet.ibm.com> Sender: owner-linux-mm@kvack.org List-ID: To: "Kirill A. Shutemov" Cc: Johannes Weiner , Andrew Morton , "Kirill A. Shutemov" , Andrea Arcangeli , Hugh Dickins , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oleg Nesterov , Peter Zijlstra > > > > The first time the breakpoint is hit on a page, it replaces the text > > page with anon page. Now lets assume we insert breakpoints in all the > > pages in a range. Here each page is individually replaced by a non THP > > anonpage. (since we dont have bulk breakpoint insertion support, > > breakpoint insertion happens one at a time). Now the only interesting > > case may be when each of these replaced pages happen to be physically > > contiguous so that THP kicks in to replace all of these pages with one > > THP page. Can happen in practice? > > > > Are there any other cases that I have missed? > > We use a hack in our applications where we open /proc/self/maps, copy > text segments to a staging area, then create overlay anon mappings on > top and copy the text back into them. Now we have THP-backed text and > very little iTLB pressure :-) > > That said, we haven't run into the uprobes issue yet. > Thanks Johannes, Kirill, Rik. Reviewed-by: Srikar Dronamraju -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org