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[209.132.180.67]) by mx.google.com with ESMTP id b2si2122053pjw.80.2019.06.07.08.52.35; Fri, 07 Jun 2019 08:52:35 -0700 (PDT) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=VCg9aAIj; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732162AbfFGPwe (ORCPT + 30 others); Fri, 7 Jun 2019 11:52:34 -0400 Received: from mail.kernel.org ([198.145.29.99]:34928 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731880AbfFGPtM (ORCPT ); Fri, 7 Jun 2019 11:49:12 -0400 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 E3D9C21473; Fri, 7 Jun 2019 15:49:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559922551; bh=hC9OXVXPHX4MXhpkf48AC7gVpWOSOd+PECCwdEPvt3g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VCg9aAIj47n0wSUoWaAf9JeI9EEigij98+QnELI0uHq7ZjDEjbY7BMWS6lDS5zcFq kZoQef7BAmXCvW0AModZi23A7mbI3W1tfabt9sR8S1m7RA4o3v0bh0KtknmXOtDOCx nNggX6Im5vP6FQUmUpVI+W/QZscd6BRFc501jQp4= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Suzuki K Poulose , Marc Zyngier , Mel Gorman , Anshuman Khandual , Michal Hocko , Qian Cai , Andrew Morton , Linus Torvalds Subject: [PATCH 5.1 53/85] mm, compaction: make sure we isolate a valid PFN Date: Fri, 7 Jun 2019 17:39:38 +0200 Message-Id: <20190607153855.424689098@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190607153849.101321647@linuxfoundation.org> References: <20190607153849.101321647@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Suzuki K Poulose commit e577c8b64d58fe307ea4d5149d31615df2d90861 upstream. 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(). Link: http://lkml.kernel.org/r/1558711908-15688-1-git-send-email-suzuki.poulose@arm.com Fixes: 5a811889de10f1eb ("mm, compaction: use free lists to quickly locate a migration target") Signed-off-by: Suzuki K Poulose Reported-by: Marc Zyngier Reviewed-by: Mel Gorman Reviewed-by: Anshuman Khandual Cc: Michal Hocko Cc: Qian Cai Cc: Marc Zyngier Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1397,7 +1397,7 @@ fast_isolate_freepages(struct compact_co page = pfn_to_page(highest); cc->free_pfn = highest; } else { - if (cc->direct_compaction) { + if (cc->direct_compaction && pfn_valid(min_pfn)) { page = pfn_to_page(min_pfn); cc->free_pfn = min_pfn; }