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=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,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 DB10DC43219 for ; Fri, 3 May 2019 07:51:57 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 9076F205F4 for ; Fri, 3 May 2019 07:51:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9076F205F4 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 44wPV40lJTzDqvd for ; Fri, 3 May 2019 17:51:56 +1000 (AEST) Received: from ozlabs.org (bilbo.ozlabs.org [203.11.71.1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 44wNKY2m0pzDqS6 for ; Fri, 3 May 2019 16:59:29 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dmarc=none (p=none dis=none) header.from=ellerman.id.au Received: by ozlabs.org (Postfix, from userid 1034) id 44wNKW2x7Jz9sPC; Fri, 3 May 2019 16:59:27 +1000 (AEST) X-powerpc-patch-notification: thanks X-powerpc-patch-commit: 2c474c03505677cfd987d52e8bf42abe8c270529 X-Patchwork-Hint: ignore In-Reply-To: <20190430075907.7701-1-aneesh.kumar@linux.ibm.com> To: "Aneesh Kumar K.V" , npiggin@gmail.com, paulus@samba.org From: Michael Ellerman Subject: Re: [PATCH] powerpc/mm/radix: Fix kernel crash when running subpage protect test Message-Id: <44wNKW2x7Jz9sPC@ozlabs.org> Date: Fri, 3 May 2019 16:59:27 +1000 (AEST) X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sachin Sant , "Aneesh Kumar K.V" , linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On Tue, 2019-04-30 at 07:59:07 UTC, "Aneesh Kumar K.V" wrote: > This patch fixes the below crash by making sure we touch the subpage protection > related structures only if we know they are allocated on the platform. With > radix translation we don't allocate hash context at all and trying to access > subpage_prot_table results in > > Faulting instruction address: 0xc00000000008bdb4 > Oops: Kernel access of bad area, sig: 11 [#1] > LE PAGE_SIZE=64K MMU=Radix MMU=Hash SMP NR_CPUS=2048 NUMA PowerNV > .... > NIP [c00000000008bdb4] sys_subpage_prot+0x74/0x590 > LR [c00000000000b688] system_call+0x5c/0x70 > Call Trace: > [c00020002c6b7d30] [c00020002c6b7d90] 0xc00020002c6b7d90 (unreliable) > [c00020002c6b7e20] [c00000000000b688] system_call+0x5c/0x70 > Instruction dump: > fb61ffd8 fb81ffe0 fba1ffe8 fbc1fff0 fbe1fff8 f821ff11 e92d1178 f9210068 > 39200000 e92d0968 ebe90630 e93f03e8 60000000 3860fffe e9410068 > > We also move the subpage_prot_table with mmp_sem held to avoid racec > between two parallel subpage_prot syscall. > > Reported-by: Sachin Sant > Signed-off-by: Aneesh Kumar K.V > Tested-by: Sachin Sant > Applied to powerpc next, thanks. https://git.kernel.org/powerpc/c/2c474c03505677cfd987d52e8bf42abe cheers