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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 DFF89C43603 for ; Mon, 16 Dec 2019 12:00:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B1AEB206CB for ; Mon, 16 Dec 2019 12:00:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1576497648; bh=gdRI55Cy2ICA0TNl1eKxfYvXJBwoyhiX2MQiLtev0Uk=; h=Subject:To:Cc:From:Date:List-ID:From; b=B9tyCXnlfIFV5O9iWld7pPDbpysuKYDPaj89ZgL5DIgnediw5KsEcizIV3w6HRxTi lZeEljizhuaSeEHMo8vIqZZpXY6wT7QBxJ2JOQwET+Nz+lRaR0CKU8sFnOUd7f1l5M n1QfxFApwEkYD8QthJXKomIowDAkEnBuBEtOeqgE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727454AbfLPMAs (ORCPT ); Mon, 16 Dec 2019 07:00:48 -0500 Received: from out1-smtp.messagingengine.com ([66.111.4.25]:44987 "EHLO out1-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727335AbfLPMAs (ORCPT ); Mon, 16 Dec 2019 07:00:48 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id 0ACA521FE0; Mon, 16 Dec 2019 07:00:47 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Mon, 16 Dec 2019 07:00:47 -0500 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=fm1; bh=1Vj0jR gPCLW7y5xUfmj34WVdQnhBG8mBAHeKcNj2538=; b=u+GQbfwrgnPRe9sjZLkmOu gj11A/PcfOP/ZtMuKvoZGAbovotQlV+uN7SBG2Ta3kIVL8nq4NvX3ddjqo22Njan 7xiVjF3X0yMsAYt05I0TmfqgtFzQUAuesMK43fG9eqTa8V2OQY3C91kXloREwsVK qqmcGOlt3iqrCt2d7KAs2AKFrNsGnoQ+a9uAnBfBeuJwlF3zeHcUBdU6HQF1fpND EWNMWOn1F1N2Im2jc0zGscPOx1IGOoDeR+56AdNRiye4WQzTe0AiaU1qtF52THNv nOvu05/90yUh3fmrRuPaf8qJO4QvlhG0X7bR1+fOu9JfGotYGvzd7OOOrb8y8XkA == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedufedrvddthedgfeehucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuffhomhgrihhnpehkvghrnhgvlhdrohhrghenucfkphepkeefrdekiedrkeelrd dutdejnecurfgrrhgrmhepmhgrihhlfhhrohhmpehgrhgvgheskhhrohgrhhdrtghomhen ucevlhhushhtvghrufhiiigvpedt X-ME-Proxy: Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) by mail.messagingengine.com (Postfix) with ESMTPA id CE4F18005A; Mon, 16 Dec 2019 07:00:45 -0500 (EST) Subject: FAILED: patch "[PATCH] mm/memory.c: fix a huge pud insertion race during faulting" failed to apply to 4.19-stable tree To: thellstrom@vmware.com, akpm@linux-foundation.org, arnd@arndb.de, kirill.shutemov@linux.intel.com, stable@vger.kernel.org, torvalds@linux-foundation.org, willy@infradead.org Cc: From: Date: Mon, 16 Dec 2019 13:00:44 +0100 Message-ID: <1576497644874@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.19-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 625110b5e9dae9074d8a7e67dd07f821a053eed7 Mon Sep 17 00:00:00 2001 From: Thomas Hellstrom Date: Sat, 30 Nov 2019 17:51:32 -0800 Subject: [PATCH] mm/memory.c: fix a huge pud insertion race during faulting A huge pud page can theoretically be faulted in racing with pmd_alloc() in __handle_mm_fault(). That will lead to pmd_alloc() returning an invalid pmd pointer. Fix this by adding a pud_trans_unstable() function similar to pmd_trans_unstable() and check whether the pud is really stable before using the pmd pointer. Race: Thread 1: Thread 2: Comment create_huge_pud() Fallback - not taken. create_huge_pud() Taken. pmd_alloc() Returns an invalid pointer. This will result in user-visible huge page data corruption. Note that this was caught during a code audit rather than a real experienced problem. It looks to me like the only implementation that currently creates huge pud pagetable entries is dev_dax_huge_fault() which doesn't appear to care much about private (COW) mappings or write-tracking which is, I believe, a prerequisite for create_huge_pud() falling back on thread 1, but not in thread 2. Link: http://lkml.kernel.org/r/20191115115808.21181-2-thomas_os@shipmail.org Fixes: a00cc7d9dd93 ("mm, x86: add support for PUD-sized transparent hugepages") Signed-off-by: Thomas Hellstrom Acked-by: Kirill A. Shutemov Cc: Arnd Bergmann Cc: Matthew Wilcox Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds diff --git a/include/asm-generic/pgtable.h b/include/asm-generic/pgtable.h index 3127f9028f54..798ea36a0549 100644 --- a/include/asm-generic/pgtable.h +++ b/include/asm-generic/pgtable.h @@ -938,6 +938,31 @@ static inline int pud_trans_huge(pud_t pud) } #endif +/* See pmd_none_or_trans_huge_or_clear_bad for discussion. */ +static inline int pud_none_or_trans_huge_or_dev_or_clear_bad(pud_t *pud) +{ + pud_t pudval = READ_ONCE(*pud); + + if (pud_none(pudval) || pud_trans_huge(pudval) || pud_devmap(pudval)) + return 1; + if (unlikely(pud_bad(pudval))) { + pud_clear_bad(pud); + return 1; + } + return 0; +} + +/* See pmd_trans_unstable for discussion. */ +static inline int pud_trans_unstable(pud_t *pud) +{ +#if defined(CONFIG_TRANSPARENT_HUGEPAGE) && \ + defined(CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD) + return pud_none_or_trans_huge_or_dev_or_clear_bad(pud); +#else + return 0; +#endif +} + #ifndef pmd_read_atomic static inline pmd_t pmd_read_atomic(pmd_t *pmdp) { diff --git a/mm/memory.c b/mm/memory.c index 62b5cce653f6..c3902201989f 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -4010,6 +4010,7 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, vmf.pud = pud_alloc(mm, p4d, address); if (!vmf.pud) return VM_FAULT_OOM; +retry_pud: if (pud_none(*vmf.pud) && __transparent_hugepage_enabled(vma)) { ret = create_huge_pud(&vmf); if (!(ret & VM_FAULT_FALLBACK)) @@ -4036,6 +4037,11 @@ static vm_fault_t __handle_mm_fault(struct vm_area_struct *vma, vmf.pmd = pmd_alloc(mm, vmf.pud, address); if (!vmf.pmd) return VM_FAULT_OOM; + + /* Huge pud page fault raced with pmd_alloc? */ + if (pud_trans_unstable(vmf.pud)) + goto retry_pud; + if (pmd_none(*vmf.pmd) && __transparent_hugepage_enabled(vma)) { ret = create_huge_pmd(&vmf); if (!(ret & VM_FAULT_FALLBACK))