From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f198.google.com (mail-pf0-f198.google.com [209.85.192.198]) by kanga.kvack.org (Postfix) with ESMTP id AC17E6B002B for ; Fri, 6 Apr 2018 16:58:30 -0400 (EDT) Received: by mail-pf0-f198.google.com with SMTP id k17so1302396pfj.10 for ; Fri, 06 Apr 2018 13:58:30 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [2607:7c80:54:e::133]) by mx.google.com with ESMTPS id y7si7497692pgp.727.2018.04.06.13.58.29 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Fri, 06 Apr 2018 13:58:29 -0700 (PDT) Date: Fri, 6 Apr 2018 13:58:28 -0700 From: Matthew Wilcox Subject: Re: Requesting to share current work items Message-ID: <20180406205828.GA9618@bombadil.infradead.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Chandan Vn Cc: linux-mm@kvack.org On Fri, Apr 06, 2018 at 07:20:47AM +0000, Chandan Vn wrote: > Hi, > > I would like to start contributing to linux-mm community. > Could you please let me know the current work items which I can start > working on. > > Please note that I have been working on linux-mm from past 4 years but > mostly proprietary or not yet mainlined vendor codebase. We had a report of a problem a few weeks ago that I don't know if anybody is looking at yet. Perhaps you'd like to try fixing it. The report says that, under some unidentified workload, calling vmalloc can take many hundreds of milliseconds, and the problem is in alloc_vmap_area(). So a good plan of work would be to devise a kernel module which can produce a highly-fragmented vmap area, and demonstrate the problem. Once you've got a reliable reproducer, you can look at how to fix this problem. We probably need a better data structure; either enhance the existing rbtree of free areas, or change the data structure.