From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id B63FC6B0003 for ; Wed, 28 Feb 2018 02:13:08 -0500 (EST) Received: by mail-pg0-f71.google.com with SMTP id o11so774609pgp.14 for ; Tue, 27 Feb 2018 23:13:08 -0800 (PST) Received: from EUR03-AM5-obe.outbound.protection.outlook.com (mail-eopbgr30120.outbound.protection.outlook.com. [40.107.3.120]) by mx.google.com with ESMTPS id u62si657215pgd.579.2018.02.27.23.13.06 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 27 Feb 2018 23:13:07 -0800 (PST) Subject: Re: [PATCH v5 0/4] vm: add a syscall to map a process memory into a pipe References: <1515479453-14672-1-git-send-email-rppt@linux.vnet.ibm.com> <20180220164406.3ec34509376f16841dc66e34@linux-foundation.org> <3122ec5a-7f73-f6b4-33ea-8c10ef32e5b0@virtuozzo.com> <20180227021818.GA31386@altlinux.org> From: Pavel Emelyanov Message-ID: <627ac4f8-a52d-0582-0c9e-e70ea667fa7e@virtuozzo.com> Date: Wed, 28 Feb 2018 10:12:55 +0300 MIME-Version: 1.0 In-Reply-To: <20180227021818.GA31386@altlinux.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Mike Rapoport , Alexander Viro , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org, criu@openvz.org, gdb@sourceware.org, devel@lists.open-mpi.org, rr-dev@mozilla.org, Arnd Bergmann , Michael Kerrisk , Thomas Gleixner , Josh Triplett , Jann Horn , Greg KH , Andrei Vagin On 02/27/2018 05:18 AM, Dmitry V. Levin wrote: > On Mon, Feb 26, 2018 at 12:02:25PM +0300, Pavel Emelyanov wrote: >> On 02/21/2018 03:44 AM, Andrew Morton wrote: >>> On Tue, 9 Jan 2018 08:30:49 +0200 Mike Rapoport wrote: >>> >>>> This patches introduces new process_vmsplice system call that combines >>>> functionality of process_vm_read and vmsplice. >>> >>> All seems fairly strightforward. The big question is: do we know that >>> people will actually use this, and get sufficient value from it to >>> justify its addition? >> >> Yes, that's what bothers us a lot too :) I've tried to start with finding out if anyone >> used the sys_read/write_process_vm() calls, but failed :( Does anybody know how popular >> these syscalls are? > > Well, process_vm_readv itself is quite popular, it's used by debuggers nowadays, > see e.g. > $ strace -qq -esignal=none -eprocess_vm_readv strace -qq -o/dev/null cat /dev/null I see. Well, yes, this use-case will not benefit much from remote splice. How about more interactive debug by, say, gdb? It may attach, then splice all the memory, then analyze the victim code/data w/o copying it to its address space? -- Pavel -- 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