linux-kernel - Race condition in HR timers that cause double insertion and hard lockup -- all latest versions

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Message-ID: <5dfbace37c434be58ed26ea524aa0675@AM3PR06MB388.eurprd06.prod.outlook.com>
Date:	Tue, 2 Sep 2014 15:45:59 +0000
From:	Itzcak Pechtalt <itzcak@...shnetworks.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:	Alan Cox <alan@...hat.com>, Linus Torvalds <torvalds@...l.org>
Subject: Race condition in HR timers that cause double insertion and hard
 lockup -- all latest versions

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@...nel-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

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