From 9d796e66230205cd3366f5660387bd9ecca9d336 Mon Sep 17 00:00:00 2001 From: Andrey Ryabinin Date: Thu, 16 Apr 2015 12:48:10 -0700 Subject: [PATCH] gcov: fix softlockups gcov profiling if enabled with other heavy compile-time instrumentation like KASan could trigger following softlockups: NMI watchdog: BUG: soft lockup - CPU#0 stuck for 22s! [swapper/0:1] Modules linked in: irq event stamp: 22823276 hardirqs last enabled at (22823275): [] mutex_lock_nested+0x7d9/0x930 hardirqs last disabled at (22823276): [] apic_timer_interrupt+0x6d/0x80 softirqs last enabled at (22823172): [] __do_softirq+0x4db/0x729 softirqs last disabled at (22823167): [] irq_exit+0x7d/0x15b CPU: 0 PID: 1 Comm: swapper/0 Tainted: G W 3.19.0-05245-gbb33326-dirty #3 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.7.5.1-0-g8936dbb-20141113_115728-nilsson.home.kraxel.org 04/01/2014 task: ffff88006cba8000 ti: ffff88006cbb0000 task.ti: ffff88006cbb0000 RIP: kasan_mem_to_shadow+0x1e/0x1f Call Trace: strcmp+0x28/0x70 get_node_by_name+0x66/0x99 gcov_event+0x4f/0x69e gcov_enable_events+0x54/0x7b gcov_fs_init+0xf8/0x134 do_one_initcall+0x1b2/0x288 kernel_init_freeable+0x467/0x580 kernel_init+0x15/0x18b ret_from_fork+0x7c/0xb0 Kernel panic - not syncing: softlockup: hung tasks Fix this by sticking cond_resched() in gcov_enable_events(). Signed-off-by: Andrey Ryabinin Reported-by: Fengguang Wu Cc: Peter Oberparleiter Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/gcov/base.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/gcov/base.c b/kernel/gcov/base.c index b358a802fd18..a744098e4eb7 100644 --- a/kernel/gcov/base.c +++ b/kernel/gcov/base.c @@ -18,6 +18,7 @@ #include #include #include +#include #include "gcov.h" static int gcov_events_enabled; @@ -107,8 +108,10 @@ void gcov_enable_events(void) gcov_events_enabled = 1; /* Perform event callback for previously registered entries. */ - while ((info = gcov_info_next(info))) + while ((info = gcov_info_next(info))) { gcov_event(GCOV_ADD, info); + cond_resched(); + } mutex_unlock(&gcov_lock); }