From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753200AbaAXQYw (ORCPT ); Fri, 24 Jan 2014 11:24:52 -0500 Received: from www.linutronix.de ([62.245.132.108]:57689 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751587AbaAXQYv (ORCPT ); Fri, 24 Jan 2014 11:24:51 -0500 From: Sebastian Andrzej Siewior To: linux-kernel@vger.kernel.org Cc: linux-rt-users@vger.kernel.org, Sebastian Andrzej Siewior Subject: [PATCH RT] arm/unwind: fail on unwind in irq disabled regions Date: Fri, 24 Jan 2014 17:24:23 +0100 Message-Id: <1390580663-28869-1-git-send-email-bigeasy@linutronix.de> X-Mailer: git-send-email 1.8.5.3 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mostly unwind is done with irqs enabled however SLUB may call it with irqs disabled while creating a new SLUB cache. I had system freeze while loading a module which called kmem_cache_create() on init. That means SLUB's __slab_alloc() disabled interrupts and then ->new_slab_objects() ->new_slab() ->setup_object() ->setup_object_debug() ->init_tracking() ->set_track() ->save_stack_trace() ->save_stack_trace_tsk() ->walk_stackframe() ->unwind_frame() ->unwind_find_idx() =>spin_lock_irqsave(&unwind_lock); I would prefer not to turn this into a raw lock so for now it will just fail if it is called with irqs disabled which might return a few "empty" traces… Signed-off-by: Sebastian Andrzej Siewior --- arch/arm/kernel/unwind.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/arch/arm/kernel/unwind.c b/arch/arm/kernel/unwind.c index 00df012..2af232d 100644 --- a/arch/arm/kernel/unwind.c +++ b/arch/arm/kernel/unwind.c @@ -195,6 +195,11 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr) /* module unwind tables */ struct unwind_table *table; +#ifdef CONFIG_PREEMPT_RT_FULL + if (irqs_disabled()) + goto out; +#endif + spin_lock_irqsave(&unwind_lock, flags); list_for_each_entry(table, &unwind_tables, list) { if (addr >= table->begin_addr && @@ -211,6 +216,7 @@ static const struct unwind_idx *unwind_find_idx(unsigned long addr) } pr_debug("%s: idx = %p\n", __func__, idx); +out: return idx; } @@ -345,7 +351,9 @@ int unwind_frame(struct stackframe *frame) idx = unwind_find_idx(frame->pc); if (!idx) { +#ifndef CONFIG_PREEMPT_RT_FULL pr_warning("unwind: Index not found %08lx\n", frame->pc); +#endif return -URC_FAILURE; } -- 1.8.5.3