From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f71.google.com (mail-pl0-f71.google.com [209.85.160.71]) by kanga.kvack.org (Postfix) with ESMTP id 1228C6B02D0 for ; Tue, 15 May 2018 17:40:50 -0400 (EDT) Received: by mail-pl0-f71.google.com with SMTP id i1-v6so1010292pld.11 for ; Tue, 15 May 2018 14:40:50 -0700 (PDT) Received: from g2t2354.austin.hpe.com (g2t2354.austin.hpe.com. [15.233.44.27]) by mx.google.com with ESMTPS id d21-v6si939533pll.147.2018.05.15.14.40.48 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 15 May 2018 14:40:48 -0700 (PDT) From: Toshi Kani Subject: [PATCH v2 1/3] x86/mm: disable ioremap free page handling on x86-PAE Date: Tue, 15 May 2018 15:39:29 -0600 Message-Id: <20180515213931.23885-2-toshi.kani@hpe.com> In-Reply-To: <20180515213931.23885-1-toshi.kani@hpe.com> References: <20180515213931.23885-1-toshi.kani@hpe.com> Sender: owner-linux-mm@kvack.org List-ID: To: mhocko@suse.com, akpm@linux-foundation.org, tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com Cc: cpandya@codeaurora.org, linux-mm@kvack.org, x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Toshi Kani , Joerg Roedel , stable@vger.kernel.org ioremap() supports pmd mappings on x86-PAE. However, kernel's pmd tables are not shared among processes on x86-PAE. Therefore, any update to sync'd pmd entries need re-syncing. Freeing a pte page also leads to a vmalloc fault and hits the BUG_ON in vmalloc_sync_one(). Disable free page handling on x86-PAE. pud_free_pmd_page() and pmd_free_pte_page() simply return 0 if a given pud/pmd entry is present. This assures that ioremap() does not update sync'd pmd entries at the cost of falling back to pte mappings. Fixes: 28ee90fe6048 ("x86/mm: implement free pmd/pte page interfaces") Reported-by: Joerg Roedel Signed-off-by: Toshi Kani Cc: Andrew Morton Cc: Michal Hocko Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Joerg Roedel Cc: --- arch/x86/mm/pgtable.c | 19 +++++++++++++++++++ 1 file changed, 19 insertions(+) diff --git a/arch/x86/mm/pgtable.c b/arch/x86/mm/pgtable.c index ffc8c13c50e4..08cdd7c13619 100644 --- a/arch/x86/mm/pgtable.c +++ b/arch/x86/mm/pgtable.c @@ -715,6 +715,7 @@ int pmd_clear_huge(pmd_t *pmd) return 0; } +#ifdef CONFIG_X86_64 /** * pud_free_pmd_page - Clear pud entry and free pmd page. * @pud: Pointer to a PUD. @@ -762,4 +763,22 @@ int pmd_free_pte_page(pmd_t *pmd) return 1; } + +#else /* !CONFIG_X86_64 */ + +int pud_free_pmd_page(pud_t *pud, unsigned long addr) +{ + return pud_none(*pud); +} + +/* + * Disable free page handling on x86-PAE. This assures that ioremap() + * does not update sync'd pmd entries. See vmalloc_sync_one(). + */ +int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) +{ + return pmd_none(*pmd); +} + +#endif /* CONFIG_X86_64 */ #endif /* CONFIG_HAVE_ARCH_HUGE_VMAP */