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=-3.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 296A0C33CA9 for ; Tue, 14 Jan 2020 00:29:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3BBA2084D for ; Tue, 14 Jan 2020 00:29:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578961756; bh=M+GCJ9ZbOzKdOKsRoSA73gXAdnJpzww7MsikwWw/RMU=; h=Date:From:To:Subject:In-Reply-To:List-ID:From; b=pLug0vnbuIemz/Y5v1dMhp6JsMc7xRNeSe0Q2625FeSOLfcPZ2RusRNN5bIkECsxo UTCofzr3ZkgLKdWyiIl6IKcx7366HVN1itzxrm0WWEt1SDc27xgRy7OOdHVltDEMwB fHihofMVHrl0OrP1VN08xGQEA+sVoCLBLeElB4dg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728931AbgANA3P (ORCPT ); Mon, 13 Jan 2020 19:29:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:45146 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728890AbgANA3P (ORCPT ); Mon, 13 Jan 2020 19:29:15 -0500 Received: from akpm3.svl.corp.google.com (unknown [104.133.8.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 1FC5F21556; Tue, 14 Jan 2020 00:29:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1578961754; bh=M+GCJ9ZbOzKdOKsRoSA73gXAdnJpzww7MsikwWw/RMU=; h=Date:From:To:Subject:In-Reply-To:From; b=eSmmal3o6L9/IqdGGxxc39S0a5UMOWwLpJUiztJdgvvRa+WhMqo8AbnB5r3kEXvoX sh6bEOA2gqVYfmV1EJo88un1OAs4XKtx8Q331uMYpi/afi5+ShoOBBreZ4EWPaQOsw YLNdc3dWSa80DNfIYSdOf6QLuuQkHREKquBR+q2s= Date: Mon, 13 Jan 2020 16:29:13 -0800 From: Andrew Morton To: thomas.willhalm@intel.com, stable@vger.kernel.org, otto.g.bruggeman@intel.com, kirill.shutemov@linux.intel.com, dan.j.williams@intel.com, aneesh.kumar@linux.vnet.ibm.com, kirill@shutemov.name, akpm@linux-foundation.org, linux-mm@kvack.org, mm-commits@vger.kernel.org, torvalds@linux-foundation.org Subject: [patch 04/11] mm/shmem.c: thp, shmem: fix conflict of above-47bit hint address and PMD alignment Message-ID: <20200114002913.UR5H3%akpm@linux-foundation.org> In-Reply-To: <20200113162831.f7d69e11e9e673c40005c9b0@linux-foundation.org> User-Agent: s-nail v14.9.15 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Kirill A. Shutemov" Subject: mm/shmem.c: thp, shmem: fix conflict of above-47bit hint address and PMD alignment Shmem/tmpfs tries to provide THP-friendly mappings if huge pages are enabled. But it doesn't work well with above-47bit hint address. Normally, the kernel doesn't create userspace mappings above 47-bit, even if the machine allows this (such as with 5-level paging on x86-64). Not all user space is ready to handle wide addresses. It's known that at least some JIT compilers use higher bits in pointers to encode their information. Userspace can ask for allocation from full address space by specifying hint address (with or without MAP_FIXED) above 47-bits. If the application doesn't need a particular address, but wants to allocate from whole address space it can specify -1 as a hint address. Unfortunately, this trick breaks THP alignment in shmem/tmp: shmem_get_unmapped_area() would not try to allocate PMD-aligned area if *any* hint address specified. This can be fixed by requesting the aligned area if the we failed to allocated at user-specified hint address. The request with inflated length will also take the user-specified hint address. This way we will not lose an allocation request from the full address space. [kirill@shutemov.name: fold in a fixup] Link: http://lkml.kernel.org/r/20191223231309.t6bh5hkbmokihpfu@box Link: http://lkml.kernel.org/r/20191220142548.7118-3-kirill.shutemov@linux.intel.com Fixes: b569bab78d8d ("x86/mm: Prepare to expose larger address space to userspace") Signed-off-by: Kirill A. Shutemov Cc: "Willhalm, Thomas" Cc: Dan Williams Cc: "Bruggeman, Otto G" Cc: "Aneesh Kumar K . V" Cc: Signed-off-by: Andrew Morton --- mm/shmem.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/shmem.c~thp-shmem-fix-conflict-of-above-47bit-hint-address-and-pmd-alignment +++ a/mm/shmem.c @@ -2107,9 +2107,10 @@ unsigned long shmem_get_unmapped_area(st /* * Our priority is to support MAP_SHARED mapped hugely; * and support MAP_PRIVATE mapped hugely too, until it is COWed. - * But if caller specified an address hint, respect that as before. + * But if caller specified an address hint and we allocated area there + * successfully, respect that as before. */ - if (uaddr) + if (uaddr == addr) return addr; if (shmem_huge != SHMEM_HUGE_FORCE) { @@ -2143,7 +2144,7 @@ unsigned long shmem_get_unmapped_area(st if (inflated_len < len) return addr; - inflated_addr = get_area(NULL, 0, inflated_len, 0, flags); + inflated_addr = get_area(NULL, uaddr, inflated_len, 0, flags); if (IS_ERR_VALUE(inflated_addr)) return addr; if (inflated_addr & ~PAGE_MASK) _