Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756563AbbGPB4H (ORCPT ); Wed, 15 Jul 2015 21:56:07 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:55680 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753504AbbGPBKq (ORCPT ); Wed, 15 Jul 2015 21:10:46 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Catalin Marinas , Kamal Mostafa Subject: [PATCH 3.19.y-ckt 108/251] arm64: Do not attempt to use init_mm in reset_context() Date: Wed, 15 Jul 2015 18:07:09 -0700 Message-Id: <1437008972-9140-109-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1437008972-9140-1-git-send-email-kamal@canonical.com> References: <1437008972-9140-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.19 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1555 Lines: 47 3.19.8-ckt4 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Catalin Marinas commit 565630d503ef24e44c252bed55571b3a0d68455f upstream. After secondary CPU boot or hotplug, the active_mm of the idle thread is &init_mm. The init_mm.pgd (swapper_pg_dir) is only meant for TTBR1_EL1 and must not be set in TTBR0_EL1. Since when active_mm == &init_mm the TTBR0_EL1 is already set to the reserved value, there is no need to perform any context reset. Signed-off-by: Catalin Marinas Signed-off-by: Kamal Mostafa --- arch/arm64/mm/context.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm64/mm/context.c b/arch/arm64/mm/context.c index baa758d..76c1e6c 100644 --- a/arch/arm64/mm/context.c +++ b/arch/arm64/mm/context.c @@ -92,6 +92,14 @@ static void reset_context(void *info) unsigned int cpu = smp_processor_id(); struct mm_struct *mm = current->active_mm; + /* + * current->active_mm could be init_mm for the idle thread immediately + * after secondary CPU boot or hotplug. TTBR0_EL1 is already set to + * the reserved value, so no need to reset any context. + */ + if (mm == &init_mm) + return; + smp_rmb(); asid = cpu_last_asid + cpu; -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/