Path: csiph.com!aioe.org!bofh.it!news.nic.it!robomod From: Greg Kroah-Hartman Newsgroups: linux.kernel Subject: [PATCH 4.0 27/58] arm64: Do not attempt to use init_mm in reset_context() Date: Sun, 19 Jul 2015 21:20:04 +0200 Message-ID: References: X-Original-To: linux-kernel@vger.kernel.org X-Mailer: git-send-email 2.4.6 User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: robomod@news.nic.it List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Approved: robomod@news.nic.it Lines: 45 Organization: linux.* mail to news gateway X-Original-Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Catalin Marinas X-Original-Date: Sun, 19 Jul 2015 12:11:05 -0700 X-Original-Message-ID: <20150719190812.217293766@linuxfoundation.org> X-Original-References: <20150719190811.308546345@linuxfoundation.org> X-Original-Sender: linux-kernel-owner@vger.kernel.org Xref: aioe.org linux.kernel:1187778 4.0-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: Greg Kroah-Hartman --- arch/arm64/mm/context.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- 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; -- 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/