From: Konstantin Khlebnikov Date: Wed, 14 Dec 2016 23:04:04 +0000 (-0800) Subject: kernel/watchdog: use nmi registers snapshot in hardlockup handler X-Git-Tag: v4.9.1~11 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=36b08b819713e587fa43b94516302dd8732dd27a;p=platform%2Fkernel%2Flinux-amlogic.git kernel/watchdog: use nmi registers snapshot in hardlockup handler commit 4d1f0fb096aedea7bb5489af93498a82e467c480 upstream. NMI handler doesn't call set_irq_regs(), it's set only by normal IRQ. Thus get_irq_regs() returns NULL or stale registers snapshot with IP/SP pointing to the code interrupted by IRQ which was interrupted by NMI. NULL isn't a problem: in this case watchdog calls dump_stack() and prints full stack trace including NMI. But if we're stuck in IRQ handler then NMI watchlog will print stack trace without IRQ part at all. This patch uses registers snapshot passed into NMI handler as arguments: these registers point exactly to the instruction interrupted by NMI. Fixes: 55537871ef66 ("kernel/watchdog.c: perform all-CPU backtrace in case of hard lockup") Link: http://lkml.kernel.org/r/146771764784.86724.6006627197118544150.stgit@buzz Signed-off-by: Konstantin Khlebnikov Cc: Jiri Kosina Cc: Ulrich Obergfell Cc: Aaron Tomlin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 9acb29f..6d1020c 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -344,7 +344,6 @@ static void watchdog_overflow_callback(struct perf_event *event, */ if (is_hardlockup()) { int this_cpu = smp_processor_id(); - struct pt_regs *regs = get_irq_regs(); /* only print hardlockups once */ if (__this_cpu_read(hard_watchdog_warn) == true)