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 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 37E81C4332F for ; Fri, 18 Nov 2022 14:37:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=ZpUn1O72eXTIMcoK4BZHy5KhEqnzZT/tha/Oa6AOv6w=; b=IkmTlB602fzklW 2r/uTQ1/DdMT93vAnJ1kwHBVEdfjsc7bqlCU9dW5vwnUG5R9chP6zXcrU6yfK3BZDKTCSjlJVkNZb RVt1VCjP2sCugl/p2cH9Ng0605Fl2qIkzo0R6yNknhSxN+11DgqJmHZBQajDF+3uF2yFMAcOSGxkJ DLVi/5i2hKtSXijLiArp3i0JTpyotlc0Lcwe+reyjcOLLNR/Zga6Qy3OVp6Uak6UTi690YKmut+pL MuBunMpcJLhL86pxPUHv9PKwkICIGmSe7LcxrUQ1nbMCR6OiK/TaPEjWv/w1cSrQTip0zjbSYar/0 a5tU9eAcHjXbwvHrnVfw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1ow2Tc-004VGu-Nf; Fri, 18 Nov 2022 14:36:21 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1ow2Ri-004U2h-4a for linux-arm-kernel@lists.infradead.org; Fri, 18 Nov 2022 14:34:23 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8105962359; Fri, 18 Nov 2022 14:34:21 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1317EC433D6; Fri, 18 Nov 2022 14:34:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1668782060; bh=K/AFbeBpdMfnp1povWUlJ9sQPjoS5eIQmxf+P/B/N1Q=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=le9JjmAa0kcJx7BscMomAw4cw3D4hq6Q51kMllQiDc/0yOf61J2DmItFSN+ictE34 TAh5Au1P0QsqAt4oWG0qyDQghsula2HaEFsoKO3HUcxe+oqzYHAuUUYU8oPNcH2Qhv rGzBOx9MSHOYMQIQpxxUPruyfVi7RhESIupN0o+P672t4EP6Sc+XTjNyIbA1nGsx62 fVYBsUCE8lxGNmCX1odb7vErCe8cVialYCvM3hkNmGpRqPv56DQnV0Lc19rnNHqWuv zS5IgA/LiZi7f8N+JN1gbV45y1JinPim9oW6OwVkEX73ZhN9T/ARI5cqQAAHTqkVxS WszpMv+z39D2Q== Date: Fri, 18 Nov 2022 14:34:15 +0000 From: Will Deacon To: Liu Shixin Cc: Catalin Marinas , Denys Vlasenko , Kefeng Wang , Anshuman Khandual , David Hildenbrand , Rafael Aquini , Pasha Tatashin , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/2] arm64/mm: fix incorrect file_map_count for invalid pmd/pud Message-ID: <20221118143414.GG4046@willie-the-truck> References: <20221117075602.2904324-1-liushixin2@huawei.com> <20221117075602.2904324-3-liushixin2@huawei.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20221117075602.2904324-3-liushixin2@huawei.com> User-Agent: Mutt/1.10.1 (2018-07-13) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20221118_063422_308535_F40A896B X-CRM114-Status: GOOD ( 22.03 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Thu, Nov 17, 2022 at 03:56:02PM +0800, Liu Shixin wrote: > The page table check trigger BUG_ON() unexpectedly when split hugepage: > > ------------[ cut here ]------------ > kernel BUG at mm/page_table_check.c:119! > Internal error: Oops - BUG: 00000000f2000800 [#1] SMP > Dumping ftrace buffer: > (ftrace buffer empty) > Modules linked in: > CPU: 7 PID: 210 Comm: transhuge-stres Not tainted 6.1.0-rc3+ #748 > Hardware name: linux,dummy-virt (DT) > pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--) > pc : page_table_check_set.isra.0+0x398/0x468 > lr : page_table_check_set.isra.0+0x1c0/0x468 > [...] > Call trace: > page_table_check_set.isra.0+0x398/0x468 > __page_table_check_pte_set+0x160/0x1c0 > __split_huge_pmd_locked+0x900/0x1648 > __split_huge_pmd+0x28c/0x3b8 > unmap_page_range+0x428/0x858 > unmap_single_vma+0xf4/0x1c8 > zap_page_range+0x2b0/0x410 > madvise_vma_behavior+0xc44/0xe78 > do_madvise+0x280/0x698 > __arm64_sys_madvise+0x90/0xe8 > invoke_syscall.constprop.0+0xdc/0x1d8 > do_el0_svc+0xf4/0x3f8 > el0_svc+0x58/0x120 > el0t_64_sync_handler+0xb8/0xc0 > el0t_64_sync+0x19c/0x1a0 > [...] > > On arm64, pmd_leaf() will return true even if the pmd is invalid due to > pmd_present_invalid() check. So in pmdp_invalidate() the file_map_count > will not only decrease once but also increase once. Then in set_pte_at(), > the file_map_count increase again, and so trigger BUG_ON() unexpectedly. > > Fix this problem by adding pmd_valid() in pmd_user_accessible_page(). > Moreover, add pud_valid() for pud_user_accessible_page() too. > > Fixes: 42b2547137f5 ("arm64/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK") > Reported-by: Denys Vlasenko > Signed-off-by: Liu Shixin > Acked-by: Pasha Tatashin > --- > arch/arm64/include/asm/pgtable.h | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h > index edf6625ce965..3bc64199aa2e 100644 > --- a/arch/arm64/include/asm/pgtable.h > +++ b/arch/arm64/include/asm/pgtable.h > @@ -863,12 +863,12 @@ static inline bool pte_user_accessible_page(pte_t pte) > > static inline bool pmd_user_accessible_page(pmd_t pmd) > { > - return pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd)); > + return pmd_valid(pmd) && pmd_leaf(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd)); Hmm, doesn't this have a funny interaction with PROT_NONE where the pmd is invalid but present? If you don't care about PROT_NONE, then you could just do: pmd_valid(pmd) && !pmd_table(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd)) but if you do care then you could do: pmd_leaf(pmd) && !pmd_present_invalid(pmd) && (pmd_user(pmd) || pmd_user_exec(pmd)) > static inline bool pud_user_accessible_page(pud_t pud) > { > - return pud_leaf(pud) && pud_user(pud); > + return pud_valid(pud) && pud_leaf(pud) && pud_user(pud); Not caused by this patch, but why don't we have something like a pud_user_exec() check here like we do for the pte and pmd levels? Will _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel