From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f170.google.com (mail-ob0-f170.google.com [209.85.214.170]) by kanga.kvack.org (Postfix) with ESMTP id AA61C6B0005 for ; Tue, 19 Jan 2016 22:17:40 -0500 (EST) Received: by mail-ob0-f170.google.com with SMTP id is5so204514186obc.0 for ; Tue, 19 Jan 2016 19:17:40 -0800 (PST) Received: from mail-oi0-x233.google.com (mail-oi0-x233.google.com. [2607:f8b0:4003:c06::233]) by mx.google.com with ESMTPS id tl9si3001711oec.45.2016.01.19.19.17.39 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 19 Jan 2016 19:17:39 -0800 (PST) Received: by mail-oi0-x233.google.com with SMTP id p187so188775193oia.2 for ; Tue, 19 Jan 2016 19:17:39 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20160119141430.8ff9c464.akpm@linux-foundation.org> References: <1453226559-17322-1-git-send-email-hannes@cmpxchg.org> <20160119141430.8ff9c464.akpm@linux-foundation.org> Date: Wed, 20 Jan 2016 08:47:39 +0530 Message-ID: Subject: Re: [PATCH] proc: revert /proc//maps [stack:TID] annotation From: Siddhesh Poyarekar Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Johannes Weiner , Shaohua Li , linux-mm@kvack.org, linux-kernel , kernel-team@fb.com On 20 January 2016 at 03:44, Andrew Morton wrote: > Any thoughts on the obvious back-compatibility concerns? ie, why did > Siddhesh implement this in the first place? My bad for not ensuring > that the changelog told us this. > > https://lkml.org/lkml/2012/1/14/25 has more info: > > : Memory mmaped by glibc for a thread stack currently shows up as a > : simple anonymous map, which makes it difficult to differentiate between > : memory usage of the thread on stack and other dynamic allocation. > : Since glibc already uses MAP_STACK to request this mapping, the > : attached patch uses this flag to add additional VM_STACK_FLAGS to the > : resulting vma so that the mapping is treated as a stack and not any > : regular anonymous mapping. Also, one may use vm_flags to decide if a > : vma is a stack. > > But even that doesn't really tell us what the actual *value* of the > patch is to end-users. The end users needed a way to identify thread stacks programmatically and there wasn't a way to do that. I'm afraid I no longer remember (or have access to the resources that would aid my memory since I changed employers) the details of their requirement. However, I did do this on my own time because I thought it was an interesting project for me and nobody really gave any feedback then as to its utility, so as far as I am concerned you could roll back the main thread maps information since the information is available in the thread-specific files. Siddhesh -- http://siddhesh.in -- 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