From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751127AbdAXW4a (ORCPT ); Tue, 24 Jan 2017 17:56:30 -0500 Received: from mail-wm0-f66.google.com ([74.125.82.66]:34308 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750854AbdAXW42 (ORCPT ); Tue, 24 Jan 2017 17:56:28 -0500 Date: Wed, 25 Jan 2017 01:56:25 +0300 From: "Kirill A. Shutemov" To: Andrew Morton Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Hugh Dickins , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oleg Nesterov , Peter Zijlstra Subject: Re: [PATCH 01/12] uprobes: split THPs before trying replace them Message-ID: <20170124225625.GD19920@node.shutemov.name> 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> <20170124143559.57cea7092a2efff940aeeef0@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170124143559.57cea7092a2efff940aeeef0@linux-foundation.org> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 24, 2017 at 02:35:59PM -0800, Andrew Morton wrote: > On Wed, 25 Jan 2017 01:22:17 +0300 "Kirill A. Shutemov" wrote: > > > On Tue, Jan 24, 2017 at 01:28:49PM -0800, Andrew Morton wrote: > > > On Tue, 24 Jan 2017 19:28:13 +0300 "Kirill A. Shutemov" wrote: > > > > > > > For THPs page_check_address() always fails. It's better to split them > > > > first before trying to replace. > > > > > > So what does this mean. uprobes simply fails to work when trying to > > > place a probe into a THP memory region? > > > > Looks like we can end up with endless retry loop in uprobe_write_opcode(). > > > > > How come nobody noticed (and reported) this when using the feature? > > > > I guess it's not often used for anon memory. > > OK, can we please include discussion of these things in the changelog? Okay, I'll try to come up with a test case too. -- Kirill A. Shutemov From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wj0-f199.google.com (mail-wj0-f199.google.com [209.85.210.199]) by kanga.kvack.org (Postfix) with ESMTP id 501ED6B026A for ; Tue, 24 Jan 2017 17:56:28 -0500 (EST) Received: by mail-wj0-f199.google.com with SMTP id jz4so32251855wjb.5 for ; Tue, 24 Jan 2017 14:56:28 -0800 (PST) Received: from mail-wm0-x242.google.com (mail-wm0-x242.google.com. [2a00:1450:400c:c09::242]) by mx.google.com with ESMTPS id 1si24450104wri.286.2017.01.24.14.56.27 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 24 Jan 2017 14:56:27 -0800 (PST) Received: by mail-wm0-x242.google.com with SMTP id r144so38242050wme.0 for ; Tue, 24 Jan 2017 14:56:27 -0800 (PST) Date: Wed, 25 Jan 2017 01:56:25 +0300 From: "Kirill A. Shutemov" Subject: Re: [PATCH 01/12] uprobes: split THPs before trying replace them Message-ID: <20170124225625.GD19920@node.shutemov.name> 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> <20170124143559.57cea7092a2efff940aeeef0@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170124143559.57cea7092a2efff940aeeef0@linux-foundation.org> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: "Kirill A. Shutemov" , Andrea Arcangeli , Hugh Dickins , Rik van Riel , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Oleg Nesterov , Peter Zijlstra On Tue, Jan 24, 2017 at 02:35:59PM -0800, Andrew Morton wrote: > On Wed, 25 Jan 2017 01:22:17 +0300 "Kirill A. Shutemov" wrote: > > > On Tue, Jan 24, 2017 at 01:28:49PM -0800, Andrew Morton wrote: > > > On Tue, 24 Jan 2017 19:28:13 +0300 "Kirill A. Shutemov" wrote: > > > > > > > For THPs page_check_address() always fails. It's better to split them > > > > first before trying to replace. > > > > > > So what does this mean. uprobes simply fails to work when trying to > > > place a probe into a THP memory region? > > > > Looks like we can end up with endless retry loop in uprobe_write_opcode(). > > > > > How come nobody noticed (and reported) this when using the feature? > > > > I guess it's not often used for anon memory. > > OK, can we please include discussion of these things in the changelog? Okay, I'll try to come up with a test case too. -- Kirill A. Shutemov -- 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