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=-13.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 DB617C71155 for ; Thu, 3 Dec 2020 06:29:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6E6BF2085B for ; Thu, 3 Dec 2020 06:29:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729570AbgLCG2x (ORCPT ); Thu, 3 Dec 2020 01:28:53 -0500 Received: from mga12.intel.com ([192.55.52.136]:9697 "EHLO mga12.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726405AbgLCG2x (ORCPT ); Thu, 3 Dec 2020 01:28:53 -0500 IronPort-SDR: YPCOd+iSU1/nozAEaBfC/L0aYaH8kAj7tGPMuwILBKDdXay4/5FBVdnJ1PaXsYq8ZJPMKdIsqh Ab/0eQ9LZjUw== X-IronPort-AV: E=McAfee;i="6000,8403,9823"; a="152395954" X-IronPort-AV: E=Sophos;i="5.78,388,1599548400"; d="scan'208";a="152395954" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga004.jf.intel.com ([10.7.209.38]) by fmsmga106.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Dec 2020 22:28:12 -0800 IronPort-SDR: V9bG7QRBSc2woj2zV/e/nSnVoGB8yHdfSnQfplYsXbynws+qCgBnX2Wzarb5Taf0f6umx9AglE hQzNRhfpDdlg== X-IronPort-AV: E=Sophos;i="5.78,388,1599548400"; d="scan'208";a="481845558" Received: from dwillia2-desk3.jf.intel.com (HELO dwillia2-desk3.amr.corp.intel.com) ([10.54.39.25]) by orsmga004-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Dec 2020 22:28:12 -0800 Subject: [PATCH] x86/mm: Fix leak of pmd ptlock From: Dan Williams To: tglx@linutronix.de, mingo@redhat.com, bp@alien8.de Cc: stable@vger.kernel.org, Dave Hansen , Andy Lutomirski , Peter Zijlstra , x86@kernel.org, "H. Peter Anvin" , Yi Zhang , linux-kernel@vger.kernel.org, linux-nvdimm@lists.01.org, willy@infradead.org Date: Wed, 02 Dec 2020 22:28:12 -0800 Message-ID: <160697689204.605323.17629854984697045602.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.18-3-g996c MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces") introduced a new location where a pmd was released, but neglected to run the pmd page destructor. In fact, this happened previously for a different pmd release path and was fixed by commit: c283610e44ec ("x86, mm: do not leak page->ptl for pmd page tables"). This issue was hidden until recently because the failure mode is silent, but commit: b2b29d6d0119 ("mm: account PMD tables like PTE tables") ...turns the failure mode into this signature: BUG: Bad page state in process lt-pmem-ns pfn:15943d page:000000007262ed7b refcount:0 mapcount:-1024 mapping:0000000000000000 index:0x0 pfn:0x15943d flags: 0xaffff800000000() raw: 00affff800000000 dead000000000100 0000000000000000 0000000000000000 raw: 0000000000000000 ffff913a029bcc08 00000000fffffbff 0000000000000000 page dumped because: nonzero mapcount [..] dump_stack+0x8b/0xb0 bad_page.cold+0x63/0x94 free_pcp_prepare+0x224/0x270 free_unref_page+0x18/0xd0 pud_free_pmd_page+0x146/0x160 ioremap_pud_range+0xe3/0x350 ioremap_page_range+0x108/0x160 __ioremap_caller.constprop.0+0x174/0x2b0 ? memremap+0x7a/0x110 memremap+0x7a/0x110 devm_memremap+0x53/0xa0 pmem_attach_disk+0x4ed/0x530 [nd_pmem] ? __devm_release_region+0x52/0x80 nvdimm_bus_probe+0x85/0x210 [libnvdimm] Given this is a repeat occurrence it seemed prudent to look for other places where this destructor might be missing and whether a better helper is needed. try_to_free_pmd_page() looks like a candidate, but testing with setting up and tearing down pmd mappings via the dax unit tests is thus far not triggering the failure. As for a better helper pmd_free() is close, but it is a messy fit due to requiring an @mm arg. Also, ___pmd_free_tlb() wants to call paravirt_tlb_remove_table() instead of free_page(), so open-coded pgtable_pmd_page_dtor() seems the best way forward for now. Fixes: 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces") Cc: Cc: Dave Hansen Cc: Andy Lutomirski Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Ingo Molnar Cc: Borislav Petkov Cc: x86@kernel.org Cc: "H. Peter Anvin" Co-debugged-by: Matthew Wilcox Tested-by: Yi Zhang Signed-off-by: Dan Williams --- arch/x86/mm/pgtable.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index dfd82f51ba66..f6a9e2e36642 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -829,6 +829,8 @@ int pud_free_pmd_page(pud_t *pud, unsigned long addr) } free_page((unsigned long)pmd_sv); + + pgtable_pmd_page_dtor(virt_to_page(pmd)); free_page((unsigned long)pmd); return 1;