From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f71.google.com (mail-oi0-f71.google.com [209.85.218.71]) by kanga.kvack.org (Postfix) with ESMTP id 28B476B000A for ; Mon, 30 Apr 2018 14:00:28 -0400 (EDT) Received: by mail-oi0-f71.google.com with SMTP id e2-v6so3496299oii.20 for ; Mon, 30 Apr 2018 11:00:28 -0700 (PDT) Received: from g9t5009.houston.hpe.com (g9t5009.houston.hpe.com. [15.241.48.73]) by mx.google.com with ESMTPS id e124-v6si2747078oib.44.2018.04.30.11.00.26 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 30 Apr 2018 11:00:27 -0700 (PDT) From: Toshi Kani Subject: [PATCH 3/3] x86/mm: disable ioremap free page handling on x86-PAE Date: Mon, 30 Apr 2018 11:59:25 -0600 Message-Id: <20180430175925.2657-4-toshi.kani@hpe.com> In-Reply-To: <20180430175925.2657-1-toshi.kani@hpe.com> References: <20180430175925.2657-1-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 816fd41ee854..809115150d8b 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. @@ -784,4 +785,22 @@ int pmd_free_pte_page(pmd_t *pmd, unsigned long addr) 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 */