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From: Itzcak Pechtalt <itzcak@flashnetworks.com>
To: "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Cc: Alan Cox <alan@redhat.com>, Linus Torvalds <torvalds@osdl.org>
Subject: Race condition in HR timers that cause double insertion and hard lockup -- all latest versions
Date: Tue, 2 Sep 2014 15:45:59 +0000	[thread overview]
Message-ID: <5dfbace37c434be58ed26ea524aa0675@AM3PR06MB388.eurprd06.prod.outlook.com> (raw)

Hi,

I opened a bug in https://bugzilla.kernel.org/show_bug.cgi?id=83601  for this subject with full description.
There is also a short fix patch for kernel/hrtimer.c file.
Even if this bug occurs rary, however it resolves system hard lockup option.

I suspect that it was targeted by mistake to not active list (timers_realtime-clock@kernel-bugs.osdl.org).
Following is the fix patch based on kernel 3.16.1 (just simple):
diff -uNr a/kernel/hrtimer.c b/kernel/hrtimer.c
--- a/kernel/hrtimer.c 2014-08-31 20:59:52.177452123 +0300
+++ b/kernel/hrtimer.c 2014-08-31 21:02:14.972166540 +0300
@@ -941,7 +941,7 @@
if (!timerqueue_getnext(&base->active))
base->cpu_base->active_bases &= ~(1 << base->index);
out:
- timer->state = newstate;
+ timer->state = (newstate | (timer_state & HRTIMER_STATE_CALLBACK));
}

/*

Is there a chance for this patch fix to insert into next kernel release?

Thanks

Itzcak Pechtalt


             reply	other threads:[~2014-09-02 16:00 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-02 15:45 Itzcak Pechtalt [this message]
2014-09-02 16:08 ` Linus Torvalds
2014-09-02 17:46   ` Itzcak Pechtalt
2014-09-02 19:08   ` Thomas Gleixner

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