From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 371D9C2BA1A for ; Mon, 6 Apr 2020 20:23:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EEED72072F for ; Mon, 6 Apr 2020 20:23:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=intel-com.20150623.gappssmtp.com header.i=@intel-com.20150623.gappssmtp.com header.b="re0wkM9Y" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EEED72072F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=intel.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 7B46F8E0005; Mon, 6 Apr 2020 16:23:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 78C198E0001; Mon, 6 Apr 2020 16:23:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6A1498E0005; Mon, 6 Apr 2020 16:23:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0090.hostedemail.com [216.40.44.90]) by kanga.kvack.org (Postfix) with ESMTP id 51B478E0001 for ; Mon, 6 Apr 2020 16:23:08 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 0BE03A8EE for ; Mon, 6 Apr 2020 20:23:08 +0000 (UTC) X-FDA: 76678554456.28.ant80_5582aece9600f X-HE-Tag: ant80_5582aece9600f X-Filterd-Recvd-Size: 5897 Received: from mail-ed1-f66.google.com (mail-ed1-f66.google.com [209.85.208.66]) by imf35.hostedemail.com (Postfix) with ESMTP for ; Mon, 6 Apr 2020 20:23:07 +0000 (UTC) Received: by mail-ed1-f66.google.com with SMTP id m12so1105082edl.12 for ; Mon, 06 Apr 2020 13:23:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=intel-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=39PH+pwpIycTi0BsfN3QezNcOPRNhfwqmeD1bO42FHI=; b=re0wkM9Y8K0FkjQlOYTtllVGDKo96zzEV9ijGYRTSuOy69i+w+YnLmP5o40GJpt35d id1hpQ7x/EK/kFALbsL9tNzD+6SkS/Vk7I8UkLLjA6NHyxmzdfU0k6F9dHb3Eiyy+jok E18GAbSDHu0DAsBxHQd0paCz6sqrKShssxJf9In36mDsiTd1aw+w+YOkQcTzQqwKkpSd og/4qTJ341EkMIRECzta+agUB7EVJK0c/mFmjYoRMgxHoP+ySEESE37xSNcO1R2BgqbL Fbf4XVj2ywZ2YkHUG6xzQnnc3PHFsmGWn2zp1TMpAQpcERcFithJvKtO7PePdYzBw4ab d7Eg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=39PH+pwpIycTi0BsfN3QezNcOPRNhfwqmeD1bO42FHI=; b=UCoH/hykZfqmu+/sselmaMvTkQu9LSi2dLwA1ZtvXP5gFndWj9YMgCin/FJzBgun37 tvg3BHTKV1NGUgKuHuD/OF/n3vguCX5QHs86p1Pp7dznMblX28SZqRlJonzjrvmRDKuw g1b687TZkaQAlGJYtf159O6DiPFUA8Nf+DDnYuWqjO3vVXSSiVnWkCnY1ywljnXgTdlL RbNQcesozDAOzUceVNAjcs457/8+PNXg53VmEqovMy721c1gvFQaMBCAWlXOBGdB6xl0 eUMg9xvywOyMTPetJhwaoYISXU8bjNfOZUlgRyTA2Nw5P6GP59OuqXrMSmcHELW8wJO+ zxvQ== X-Gm-Message-State: AGi0PuayleQA9RyW1CCaWoWX0JlilJYPzjO72PJN9n9srOSmUrE4jFEv jIACVthvAZXNKrgna9B/qb45DAdq7dBF+uIXSsNHWA== X-Google-Smtp-Source: APiQypLKe5k4sPIdyDlAdrXh1qMjrKzUsMm7i1sTvxIVG8cUt7zm4WnRhiU6r3Bysf7eOs3J7AGGIYYvkaNPjCfcQMI= X-Received: by 2002:a17:906:6d8e:: with SMTP id h14mr1160830ejt.123.1586204586068; Mon, 06 Apr 2020 13:23:06 -0700 (PDT) MIME-Version: 1.0 References: <158500767138.2088294.17131646259803932461.stgit@dwillia2-desk3.amr.corp.intel.com> <158500773552.2088294.8756587190550753100.stgit@dwillia2-desk3.amr.corp.intel.com> <23742bb8-831f-29ff-1463-75427eec57c7@oracle.com> In-Reply-To: <23742bb8-831f-29ff-1463-75427eec57c7@oracle.com> From: Dan Williams Date: Mon, 6 Apr 2020 13:22:54 -0700 Message-ID: Subject: Re: [PATCH 11/12] device-dax: Add dis-contiguous resource support To: Joao Martins Cc: Linux MM , Dave Hansen , Christoph Hellwig , linux-nvdimm , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-Bogosity: Ham, tests=bogofilter, spamicity=0.000010, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Mon, Apr 6, 2020 at 3:46 AM Joao Martins wrote: > > On 3/23/20 11:55 PM, Dan Williams wrote: > > [...] > > > static ssize_t dev_dax_resize(struct dax_region *dax_region, > > struct dev_dax *dev_dax, resource_size_t size) > > { > > resource_size_t avail = dax_region_avail_size(dax_region), to_alloc; > > - resource_size_t dev_size = range_len(&dev_dax->range); > > + resource_size_t dev_size = dev_dax_size(dev_dax); > > struct resource *region_res = &dax_region->res; > > struct device *dev = &dev_dax->dev; > > - const char *name = dev_name(dev); > > struct resource *res, *first; > > + resource_size_t alloc = 0; > > + int rc; > > > > if (dev->driver) > > return -EBUSY; > > @@ -684,38 +766,47 @@ static ssize_t dev_dax_resize(struct dax_region *dax_region, > > * allocating a new resource. > > */ > > first = region_res->child; > > - if (!first) > > - return __alloc_dev_dax_range(dev_dax, dax_region->res.start, > > - to_alloc); > > - for (res = first; to_alloc && res; res = res->sibling) { > > +retry: > > + rc = -ENOSPC; > > + for (res = first; res; res = res->sibling) { > > struct resource *next = res->sibling; > > - resource_size_t free; > > > > /* space at the beginning of the region */ > > - free = 0; > > - if (res == first && res->start > dax_region->res.start) > > - free = res->start - dax_region->res.start; > > - if (free >= to_alloc && dev_size == 0) > > - return __alloc_dev_dax_range(dev_dax, > > - dax_region->res.start, to_alloc); > > - > > - free = 0; > > + if (res == first && res->start > dax_region->res.start) { > > + alloc = min(res->start - dax_region->res.start, > > + to_alloc); > > + rc = __alloc_dev_dax_range(dev_dax, > > + dax_region->res.start, alloc); > > You might be missing: > > first = region_res->child; > > (...) right after returning from __alloc_dev_dax_range(). Alternatively, perhaps > even moving the 'retry' label to right before the @first initialization. > > In the case that you pick space from the beginning, the child resource of the > dax region will point to first occupied region, and that changes after you pick > this space. So, IIUC, you want to adjust where you start searching free space > otherwise you end up wrongly picking that same space twice. > > If it helps, the bug can be reproduced in this unit test below, see > daxctl_test3() test: It definitely will, thanks. I'll be circling back to this now that I've settled my tree for the v5.7 window.