From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail9.hitachi.co.jp ([133.145.228.44]) by bombadil.infradead.org with esmtp (Exim 4.80.1 #2 (Red Hat Linux)) id 1ZNE1y-0001D9-M5 for kexec@lists.infradead.org; Thu, 06 Aug 2015 05:47:56 +0000 Subject: [V3 PATCH 0/4] Fix race issues among panic, NMI and crash_kexec From: Hidehiro Kawai Date: Thu, 06 Aug 2015 14:45:43 +0900 Message-ID: <20150806054543.25766.29590.stgit@softrs> MIME-Version: 1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: Jonathan Corbet , Peter Zijlstra , Ingo Molnar , "Eric W. Biederman" , "H. Peter Anvin" , Andrew Morton , Thomas Gleixner , Vivek Goyal Cc: linux-doc@vger.kernel.org, x86@kernel.org, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, Michal Hocko , Masami Hiramatsu When an HA cluster software or administrator detects non-response of a host, they issue an NMI to the host to completely stop current works and take a crash dump. If the kernel has already panicked or is capturing a crash dump at that time, further NMI can cause a crash dump failure. Also, crash_kexec() called from oops context and panic() can cause race conditions. To solve these issue, this patch set does following things: - Don't panic on NMI if the kernel has already panicked - Extend exclusion control currently done by panic_lock to crash_kexec - Introduce "noextnmi" boot option which masks external NMI at the boot time (supported only for x86) V3: - Introduce nmi_panic() macro to reduce code duplication - In the case of panic on NMI, don't return from NMI handlers if another cpu already panicked V2: - Use atomic_cmpxchg() instead of current spin_trylock() to exclude concurrent accesses to panic() and crash_kexec() - Don't introduce no-lock version of panic() and crash_kexec() --- Hidehiro Kawai (4): panic/x86: Fix re-entrance problem due to panic on NMI panic/x86: Allow cpus to save registers even if they are looping in NMI context kexec: Fix race between panic() and crash_kexec() called directly x86/apic: Introduce noextnmi boot option Documentation/kernel-parameters.txt | 4 ++++ arch/x86/kernel/apic/apic.c | 17 ++++++++++++++++- arch/x86/kernel/nmi.c | 15 +++++++++++---- arch/x86/kernel/reboot.c | 11 +++++++++++ include/linux/kernel.h | 21 +++++++++++++++++++++ kernel/kexec.c | 20 ++++++++++++++++++++ kernel/panic.c | 23 ++++++++++++++++++++--- kernel/watchdog.c | 5 +++-- 8 files changed, 106 insertions(+), 10 deletions(-) -- Hidehiro Kawai Hitachi, Ltd. Research & Development Group _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec