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=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT 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 69EC0C46460 for ; Sat, 25 May 2019 09:11:10 +0000 (UTC) Received: from mm01.cs.columbia.edu (mm01.cs.columbia.edu [128.59.11.253]) by mail.kernel.org (Postfix) with ESMTP id 2B0B92168B for ; Sat, 25 May 2019 09:11:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2B0B92168B Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvmarm-bounces@lists.cs.columbia.edu Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id B41EC4A4F4; Sat, 25 May 2019 05:11:09 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id WTPrvhj-CGAl; Sat, 25 May 2019 05:11:08 -0400 (EDT) Received: from mm01.cs.columbia.edu (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id C55ED4A4F6; Sat, 25 May 2019 05:11:05 -0400 (EDT) Received: from localhost (localhost [127.0.0.1]) by mm01.cs.columbia.edu (Postfix) with ESMTP id 932294A321 for ; Fri, 24 May 2019 11:51:59 -0400 (EDT) X-Virus-Scanned: at lists.cs.columbia.edu Received: from mm01.cs.columbia.edu ([127.0.0.1]) by localhost (mm01.cs.columbia.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 4i5fHpZdazdu for ; Fri, 24 May 2019 11:51:58 -0400 (EDT) Received: from outbound-smtp15.blacknight.com (outbound-smtp15.blacknight.com [46.22.139.232]) by mm01.cs.columbia.edu (Postfix) with ESMTPS id 354844A319 for ; Fri, 24 May 2019 11:51:58 -0400 (EDT) Received: from mail.blacknight.com (unknown [81.17.254.26]) by outbound-smtp15.blacknight.com (Postfix) with ESMTPS id EBA371C2AFC for ; Fri, 24 May 2019 16:51:56 +0100 (IST) Received: (qmail 32091 invoked from network); 24 May 2019 15:51:56 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[37.228.225.79]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 24 May 2019 15:51:56 -0000 Date: Fri, 24 May 2019 16:51:55 +0100 From: Mel Gorman To: Suzuki K Poulose Subject: Re: [PATCH] mm, compaction: Make sure we isolate a valid PFN Message-ID: <20190524155155.GQ18914@techsingularity.net> References: <20190524103924.GN18914@techsingularity.net> <1558711908-15688-1-git-send-email-suzuki.poulose@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <1558711908-15688-1-git-send-email-suzuki.poulose@arm.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-Mailman-Approved-At: Sat, 25 May 2019 05:11:04 -0400 Cc: mhocko@suse.com, kvm@vger.kernel.org, marc.zyngier@arm.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, cai@lca.pw, akpm@linux-foundation.org, kvmarm@lists.cs.columbia.edu X-BeenThere: kvmarm@lists.cs.columbia.edu X-Mailman-Version: 2.1.14 Precedence: list List-Id: Where KVM/ARM decisions are made List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu On Fri, May 24, 2019 at 04:31:48PM +0100, Suzuki K Poulose wrote: > When we have holes in a normal memory zone, we could endup having > cached_migrate_pfns which may not necessarily be valid, under heavy memory > pressure with swapping enabled ( via __reset_isolation_suitable(), triggered > by kswapd). > > Later if we fail to find a page via fast_isolate_freepages(), we may > end up using the migrate_pfn we started the search with, as valid > page. This could lead to accessing NULL pointer derefernces like below, > due to an invalid mem_section pointer. > > Unable to handle kernel NULL pointer dereference at virtual address 0000000000000008 [47/1825] > Mem abort info: > ESR = 0x96000004 > Exception class = DABT (current EL), IL = 32 bits > SET = 0, FnV = 0 > EA = 0, S1PTW = 0 > Data abort info: > ISV = 0, ISS = 0x00000004 > CM = 0, WnR = 0 > user pgtable: 4k pages, 48-bit VAs, pgdp = 0000000082f94ae9 > [0000000000000008] pgd=0000000000000000 > Internal error: Oops: 96000004 [#1] SMP > ... > CPU: 10 PID: 6080 Comm: qemu-system-aar Not tainted 510-rc1+ #6 > Hardware name: AmpereComputing(R) OSPREY EV-883832-X3-0001/OSPREY, BIOS 4819 09/25/2018 > pstate: 60000005 (nZCv daif -PAN -UAO) > pc : set_pfnblock_flags_mask+0x58/0xe8 > lr : compaction_alloc+0x300/0x950 > [...] > Process qemu-system-aar (pid: 6080, stack limit = 0x0000000095070da5) > Call trace: > set_pfnblock_flags_mask+0x58/0xe8 > compaction_alloc+0x300/0x950 > migrate_pages+0x1a4/0xbb0 > compact_zone+0x750/0xde8 > compact_zone_order+0xd8/0x118 > try_to_compact_pages+0xb4/0x290 > __alloc_pages_direct_compact+0x84/0x1e0 > __alloc_pages_nodemask+0x5e0/0xe18 > alloc_pages_vma+0x1cc/0x210 > do_huge_pmd_anonymous_page+0x108/0x7c8 > __handle_mm_fault+0xdd4/0x1190 > handle_mm_fault+0x114/0x1c0 > __get_user_pages+0x198/0x3c0 > get_user_pages_unlocked+0xb4/0x1d8 > __gfn_to_pfn_memslot+0x12c/0x3b8 > gfn_to_pfn_prot+0x4c/0x60 > kvm_handle_guest_abort+0x4b0/0xcd8 > handle_exit+0x140/0x1b8 > kvm_arch_vcpu_ioctl_run+0x260/0x768 > kvm_vcpu_ioctl+0x490/0x898 > do_vfs_ioctl+0xc4/0x898 > ksys_ioctl+0x8c/0xa0 > __arm64_sys_ioctl+0x28/0x38 > el0_svc_common+0x74/0x118 > el0_svc_handler+0x38/0x78 > el0_svc+0x8/0xc > Code: f8607840 f100001f 8b011401 9a801020 (f9400400) > ---[ end trace af6a35219325a9b6 ]--- > > The issue was reported on an arm64 server with 128GB with holes in the zone > (e.g, [32GB@4GB, 96GB@544GB]), with a swap device enabled, while running 100 KVM > guest instances. > > This patch fixes the issue by ensuring that the page belongs to a valid PFN > when we fallback to using the lower limit of the scan range upon failure in > fast_isolate_freepages(). > > Fixes: 5a811889de10f1eb ("mm, compaction: use free lists to quickly locate a migration target") > Reported-by: Marc Zyngier > Signed-off-by: Suzuki K Poulose Reviewed-by: Mel Gorman -- Mel Gorman SUSE Labs _______________________________________________ kvmarm mailing list kvmarm@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/kvmarm