From patchwork Thu Jun 29 20:50:36 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Axel Rasmussen X-Patchwork-Id: 697842 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D544DC001DF for ; Thu, 29 Jun 2023 20:50:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232000AbjF2Uu4 (ORCPT ); Thu, 29 Jun 2023 16:50:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45944 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232016AbjF2Uuy (ORCPT ); Thu, 29 Jun 2023 16:50:54 -0400 Received: from mail-yb1-xb49.google.com (mail-yb1-xb49.google.com [IPv6:2607:f8b0:4864:20::b49]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB55130F7 for ; Thu, 29 Jun 2023 13:50:50 -0700 (PDT) Received: by mail-yb1-xb49.google.com with SMTP id 3f1490d57ef6-bfee66a6398so919143276.3 for ; Thu, 29 Jun 2023 13:50:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1688071850; x=1690663850; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=R8jkAmCGbYNygAZgSop/zKP0BAnGYhZIuFEhOa1in5M=; b=a8O0wagyUtUHav4dJ+0FTU4BfULv1hqXducKGWGQFuo+G+tIPjHy7DS1ADLv5ngmlB RSngMc0CnR4cfT4Dl1/3ekbmm7f4jkeC6RGHf37xUtQNDImjBtBI9DhIP8Z9AdXeugxu EEIqVXFJE09pcCYmkIu4KbepOYvezPBB0mUQ8g4biI54D+MfCLg+3QhsHFv6yxYBACnS hW5iDv/qv08V0YHMgwph0e9b+5pGUlXVr84spJ6yslQMHWase0Q3RfrmBefxTbxnzdJF i1oPLS3gMTFjIwMQZ2twKVJdYWAw+m3Lbi649+iUQ0hPFKbJ4IuR/hqznd3O1UEd0bUk 66bA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1688071850; x=1690663850; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=R8jkAmCGbYNygAZgSop/zKP0BAnGYhZIuFEhOa1in5M=; b=fzi1hMwFT7t87k0d9Y/RsGiJT0TK2N2tbSSXyUdifGvoWiyVmhHwu+u7mfXMDZMKRf E57lWi4KhdFZ6MItJ0+NHqGPYLHm5kpDf5DKLVUn1HUO7YRFlP7mWvMtffpa3GH4//Ib XnS8oZLwbB/CmE3jUZmbgEfCsFPfkcY34ZtnOkkVGDrq3yawF4RRwM5LWfTfR3Dgub72 SL3+0cJXiTOqjLOlNJAoW6rDdSTLshFsnLkiubB6QK3SO5daRXqidftrEP8s+HsbQ0SW 3WenJx0WR2pD07IjT1N2DKKZPNSe3YVpE0Imhx3j2Auq3/sndyUPm3lMPQJYDtzNXdn3 DGgg== X-Gm-Message-State: ABy/qLboEsyTp1gQuPtcql5wZU6buPaWWdo/Rv0G50GaJ+7OI2uGgYBY bI3vnd/6jL9S1er1KHU4p+g/J40rku17nCe6OpFg X-Google-Smtp-Source: APBJJlEqqtwXeQ2F+CB5P4eAYTWY2GLrYOnygDGt3hdnYMvy8/GPfEVbxlgghXg+IFwNtZpThqff4X0A++LKH4Bo56yy X-Received: from axel.svl.corp.google.com ([2620:15c:2a3:200:e20f:5917:3efa:d4bb]) (user=axelrasmussen job=sendgmr) by 2002:a25:738e:0:b0:bcc:285c:66ea with SMTP id o136-20020a25738e000000b00bcc285c66eamr5716ybc.3.1688071850044; Thu, 29 Jun 2023 13:50:50 -0700 (PDT) Date: Thu, 29 Jun 2023 13:50:36 -0700 In-Reply-To: <20230629205040.665834-1-axelrasmussen@google.com> Mime-Version: 1.0 References: <20230629205040.665834-1-axelrasmussen@google.com> X-Mailer: git-send-email 2.41.0.255.g8b1d071c50-goog Message-ID: <20230629205040.665834-2-axelrasmussen@google.com> Subject: [PATCH v2 2/6] mm: userfaultfd: refactor hugetlb folio allocation / lookup code From: Axel Rasmussen To: Alexander Viro , Andrew Morton , Christian Brauner , David Hildenbrand , Huang Ying , Hugh Dickins , James Houghton , Jiaqi Yan , Jonathan Corbet , "Liam R. Howlett" , Miaohe Lin , Mike Kravetz , "Mike Rapoport (IBM)" , Muchun Song , Nadav Amit , Naoya Horiguchi , Peter Xu , Shuah Khan , ZhangPeng Cc: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, Axel Rasmussen Precedence: bulk List-ID: X-Mailing-List: linux-kselftest@vger.kernel.org At the top of `hugetlb_mfill_atomic_pte`, we need to get the folio we're going to be mapping. There are three basic cases we're dealing with here: 1. We're doing a UFFDIO_CONTINUE, in which case we lookup an existing folio in the pagecache, instead of allocating a new one. 2. We need to allocate a new folio. 3. We previously failed while populating our new folio, so we "returned" a temporary folio using `foliop` and had our caller retry. In a future commit I'm going to add a fourth case for UFFDIO_POISON, where we aren't going to map a folio at all (newly allocated or otherwise). This end state will be simpler, and we can re-use a bit more code, if we stop using `if (...)` to distinguish the cases. So, refactor the cases so they share most of the same code, and instead switch to `goto` to skip some parts depending on the case at hand. Signed-off-by: Axel Rasmussen --- mm/hugetlb.c | 53 +++++++++++++++++++++++++--------------------------- 1 file changed, 25 insertions(+), 28 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index bce28cca73a1..38711d49e4db 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6259,22 +6259,32 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte, if (IS_ERR(folio)) goto out; folio_in_pagecache = true; - } else if (!*foliop) { - /* If a folio already exists, then it's UFFDIO_COPY for - * a non-missing case. Return -EEXIST. - */ - if (vm_shared && - hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) { - ret = -EEXIST; - goto out; + goto ready; + } + + /* If a folio already exists, then it's UFFDIO_COPY for + * a non-missing case. Return -EEXIST. + */ + if (vm_shared && hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) { + ret = -EEXIST; + if (*foliop) { + folio_put(*foliop); + *foliop = NULL; } + goto out; + } - folio = alloc_hugetlb_folio(dst_vma, dst_addr, 0); - if (IS_ERR(folio)) { - ret = -ENOMEM; - goto out; + folio = alloc_hugetlb_folio(dst_vma, dst_addr, 0); + if (IS_ERR(folio)) { + ret = -ENOMEM; + if (*foliop) { + folio_put(*foliop); + *foliop = NULL; } + goto out; + } + if (!*foliop) { ret = copy_folio_from_user(folio, (const void __user *) src_addr, false); @@ -6302,22 +6312,7 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte, */ goto out; } - } else { - if (vm_shared && - hugetlbfs_pagecache_present(h, dst_vma, dst_addr)) { - folio_put(*foliop); - ret = -EEXIST; - *foliop = NULL; - goto out; - } - - folio = alloc_hugetlb_folio(dst_vma, dst_addr, 0); - if (IS_ERR(folio)) { - folio_put(*foliop); - ret = -ENOMEM; - *foliop = NULL; - goto out; - } + } else { /* Caller retried because we set *foliop previously */ ret = copy_user_large_folio(folio, *foliop, dst_addr, dst_vma); folio_put(*foliop); *foliop = NULL; @@ -6327,6 +6322,8 @@ int hugetlb_mfill_atomic_pte(pte_t *dst_pte, } } +ready: /* `folio` ready to map (non-NULL, populated) */ + /* * The memory barrier inside __folio_mark_uptodate makes sure that * preceding stores to the page contents become visible before