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,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 B5D04C2D0DB for ; Wed, 22 Jan 2020 09:48:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8D27D2467B for ; Wed, 22 Jan 2020 09:48:16 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579686496; bh=0BtmGPs22M/KN4vGklPBEDBxRLyDfhHLM8jbiNuJg5s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=lYzRsNEUwMHc6UC381HKnwFOvBl1JSCyxjoKDDq5+2FaQCq+KxZt76Bba6qY7LLKa L9xmVIcF15XWx5gfCuNWKRmtSe6zJ1FbwHdrYBRKpd3odQQBtAuKn1h/EJSrOfRi+0 OjraKqB9mFKDrrNTjDwOM+vZmH842FIhsNiGvunY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733077AbgAVJsP (ORCPT ); Wed, 22 Jan 2020 04:48:15 -0500 Received: from mail.kernel.org ([198.145.29.99]:32830 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2387586AbgAVJld (ORCPT ); Wed, 22 Jan 2020 04:41:33 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (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 0F33924684; Wed, 22 Jan 2020 09:41:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579686092; bh=0BtmGPs22M/KN4vGklPBEDBxRLyDfhHLM8jbiNuJg5s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=tTXheWnD7G7mgt6ZMvfm0+scsbXDLv4Gizga19rP3I9wrfSRI8pG2U19zWxHKd8lo Tq2INDtJZnzKTV76mvXLYUFw+s24O6lmj8lyWGRL+yGjuDiSAtdHvCNE5N1uwhZWkp 63ASbdWb4j70B5zpfVFYYpSq1ahlmN7LbwHNRybo= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Kirill A. Shutemov" , "Willhalm, Thomas" , Dan Williams , "Bruggeman, Otto G" , "Aneesh Kumar K . V" , Andrew Morton , Linus Torvalds Subject: [PATCH 4.19 040/103] mm/shmem.c: thp, shmem: fix conflict of above-47bit hint address and PMD alignment Date: Wed, 22 Jan 2020 10:28:56 +0100 Message-Id: <20200122092809.942698826@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092803.587683021@linuxfoundation.org> References: <20200122092803.587683021@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Kirill A. Shutemov commit 991589974d9c9ecb24ee3799ec8c415c730598a2 upstream. 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 Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/shmem.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2072,9 +2072,10 @@ 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) { @@ -2108,7 +2109,7 @@ 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)