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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 7B243C47082 for ; Tue, 8 Jun 2021 13:37:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F05C61285 for ; Tue, 8 Jun 2021 13:37:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232804AbhFHNjM (ORCPT ); Tue, 8 Jun 2021 09:39:12 -0400 Received: from wforward4-smtp.messagingengine.com ([64.147.123.34]:52665 "EHLO wforward4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232797AbhFHNjH (ORCPT ); Tue, 8 Jun 2021 09:39:07 -0400 Received: from compute3.internal (compute3.nyi.internal [10.202.2.43]) by mailforward.west.internal (Postfix) with ESMTP id 0B66E1C44; Tue, 8 Jun 2021 09:37:07 -0400 (EDT) Received: from mailfrontend1 ([10.202.2.162]) by compute3.internal (MEProxy); Tue, 08 Jun 2021 09:37:08 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm3; bh=PjdLwF 9sLXB6VXXm3MTYRl8fuxp0RNgs7vwu1/8jlwE=; b=r9O7TVm4GbhlJB2BtPVpuV AaHWwbS4+FsiBQ62NRXJ/kZFEV3w4SXhQ48RTcxY4GLX4anyPNp7qPhktcbTvcVw P0OudMEVLptlliL6Qu3dOC3AtAUgy0wDdkqMWVCT7oDV1G/qj+5i487/MrweutR7 1VmSFl2HjpjfcHrc4FJ1IMZfTJUpI7qHAB+rrhkvToOkIpXXLNdmbITuAhusQcqV MHTSOwrZKl7kx0fI1FX/e70bGBwB/2f7Jb4pPPe44aggT1Hr2XBZip0sm70ncaWp iSOTm81mM8IMAdVNkSSZJ8FA0wAsaN23gkvWqmkDQgYC1yo0J7hI/kDz27CmLQ1A == X-ME-Sender: X-ME-Received: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrfedtledgheduucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucgoufhorhhtvggutfgvtghiphdvucdlgedtmdenuc fjughrpefuvffhfffkgggtgfesthekredttddtlfenucfhrhhomhepoehgrhgvghhkhhes lhhinhhugihfohhunhgurghtihhonhdrohhrgheqnecuggftrfgrthhtvghrnhepleelle dvgeefleeltdetgedugeffgffhudffuddukeegfeelgeeigeekjefhleevnecuffhomhgr ihhnpehkvghrnhgvlhdrohhrghenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmh epmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Received: by mail.messagingengine.com (Postfix) with ESMTPA; Tue, 8 Jun 2021 09:37:06 -0400 (EDT) Subject: FAILED: patch "[PATCH] mm, hugetlb: fix simple resv_huge_pages underflow on" failed to apply to 5.4-stable tree To: almasrymina@google.com, akpm@linux-foundation.org, axelrasmussen@google.com, mike.kravetz@oracle.com, peterx@redhat.com, stable@vger.kernel.org, torvalds@linux-foundation.org Cc: From: Date: Tue, 08 Jun 2021 15:36:53 +0200 Message-ID: <16231594136129@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 5.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From d84cf06e3dd8c5c5b547b5d8931015fc536678e5 Mon Sep 17 00:00:00 2001 From: Mina Almasry Date: Fri, 4 Jun 2021 20:01:36 -0700 Subject: [PATCH] mm, hugetlb: fix simple resv_huge_pages underflow on UFFDIO_COPY The userfaultfd hugetlb tests cause a resv_huge_pages underflow. This happens when hugetlb_mcopy_atomic_pte() is called with !is_continue on an index for which we already have a page in the cache. When this happens, we allocate a second page, double consuming the reservation, and then fail to insert the page into the cache and return -EEXIST. To fix this, we first check if there is a page in the cache which already consumed the reservation, and return -EEXIST immediately if so. There is still a rare condition where we fail to copy the page contents AND race with a call for hugetlb_no_page() for this index and again we will underflow resv_huge_pages. That is fixed in a more complicated patch not targeted for -stable. Test: Hacked the code locally such that resv_huge_pages underflows produce a warning, then: ./tools/testing/selftests/vm/userfaultfd hugetlb_shared 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success ./tools/testing/selftests/vm/userfaultfd hugetlb 10 2 /tmp/kokonut_test/huge/userfaultfd_test && echo test success Both tests succeed and produce no warnings. After the test runs number of free/resv hugepages is correct. [mike.kravetz@oracle.com: changelog fixes] Link: https://lkml.kernel.org/r/20210528004649.85298-1-almasrymina@google.com Fixes: 8fb5debc5fcd ("userfaultfd: hugetlbfs: add hugetlb_mcopy_atomic_pte for userfaultfd support") Signed-off-by: Mina Almasry Reviewed-by: Mike Kravetz Cc: Axel Rasmussen Cc: Peter Xu Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 470f7b5b437e..5560b50876fb 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -4889,10 +4889,20 @@ int hugetlb_mcopy_atomic_pte(struct mm_struct *dst_mm, if (!page) goto out; } else if (!*pagep) { - ret = -ENOMEM; + /* If a page 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; + } + page = alloc_huge_page(dst_vma, dst_addr, 0); - if (IS_ERR(page)) + if (IS_ERR(page)) { + ret = -ENOMEM; goto out; + } ret = copy_huge_page_from_user(page, (const void __user *) src_addr,