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Message-Id: <20081216152143.88caba51.ytakahashi@miraclelinux.com>
Date: Tue, 16 Dec 2008 15:21:43 +0900
From: Yoshihiro Takahashi <ytakahashi@...aclelinux.com>
To: linux-kernel@...r.kernel.org
Subject: kdump hangs up by Sysrq+C trigger in high load.
Hi.
kdump hangs up by Sysrq+C trigger once in about 10 times in high load.
After the above occurs, kdump cannot collect vmcores with NMI button.
When waiting_for_crash_ipi does case more than 0, mdelay seem to make
a stall.
While nmi_shootdown_cpus(), mdelay may not work since interruption is
disable. (ex. when crashing kernel by NMI interruption, all
interruption may be disabled.).
So I think that it should use other way (TSC) instead of mdelay() in
nmi_shootdown_cpus().
Here is the log.
--
SysRq : Trigger a crashdump
BUG: warning at arch/x86/kernel/crash.c:107/nmi_shootdown_cpus() (Not tainted)
Signed-off-by: Yoshihiro Takahashi <ytakahashi@...aclelinux.com>
---
crash.c | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
index 2685538..fc63636 100644
--- a/arch/x86/kernel/crash.c
+++ b/arch/x86/kernel/crash.c
@@ -89,7 +89,8 @@ static struct notifier_block crash_nmi_nb = {
static void nmi_shootdown_cpus(void)
{
- unsigned long msecs;
+ int i, tsc_wait, tsc_count;
+ unsigned long tsc_start, tsc_now, tsc_delay;
atomic_set(&waiting_for_crash_ipi, num_online_cpus() - 1);
/* Would it be better to replace the trap vector here? */
@@ -102,10 +103,25 @@ static void nmi_shootdown_cpus(void)
smp_send_nmi_allbutself();
- msecs = 1000; /* Wait at most a second for the other cpus to stop */
- while ((atomic_read(&waiting_for_crash_ipi) > 0) && msecs) {
- mdelay(1);
- msecs--;
+ tsc_delay = HZ; /* Wait at most a second for the other cpus to stop */
+ while ((atomic_read(&waiting_for_crash_ipi) > 0) && tsc_delay) {
+ tsc_wait = 1000000; /* msec */
+ tsc_count = 16384;
+ while (tsc_wait > 0) {
+ if (tsc_count-- < 0) {
+ break;
+ }
+ tsc_start = get_cycles();
+ for (i = 0; i < 100000; i++) {
+ ;
+ }
+ tsc_now = get_cycles();
+ tsc_wait -= tsc_now - tsc_start;
+ }
+ if (tsc_count < 0) {
+ break;
+ }
+ tsc_delay--;
}
/* Leave the nmi callback set */
--
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