Add patch to fix lock inversion introduced in 3.0.7

2011-10-18 15:47:52 -04:00 · 2011-10-18 15:47:52 -04:00 · a7fc75d2d8
parent 7be21bba89
commit a7fc75d2d8
2 changed files with 154 additions and 1 deletions
--- a/cputimer-Cure-lock-inversion.patch
+++ b/cputimer-Cure-lock-inversion.patch
@ -0,0 +1,148 @@
+Path: news.gmane.org!not-for-mail
+From: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Newsgroups: gmane.linux.kernel
+Subject: Re: Linux 3.1-rc9
+Date: Tue, 18 Oct 2011 11:05:13 +0200
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+Cc: Linus Torvalds <torvalds@linux-foundation.org>,
+	Simon Kirby <sim@hostway.ca>,
+	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
+	Dave Jones <davej@redhat.com>,
+	Martin Schwidefsky <schwidefsky@de.ibm.com>,
+	Ingo Molnar <mingo@elte.hu>
+To: Thomas Gleixner <tglx@linutronix.de>
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+
+On Tue, 2011-10-18 at 10:39 +0200, Thomas Gleixner wrote:
+> On Mon, 17 Oct 2011, Thomas Gleixner wrote:
+> > That said, I really need some sleep before I can make a final
+> > judgement on that horror. The call paths are such an intermingled mess
+> > that it's not funny anymore. I do that tomorrow morning first thing.
+> 
+> The patch is safe and the exit race just existed in my confused tired
+> brain. Peter, can you please provide a changelog. That wants a cc
+> stable as well, because that deadlock causing commit hit 3.0.7 :( 
+
+---
+Subject: cputimer: Cure lock inversion
+From: Peter Zijlstra <a.p.zijlstra@chello.nl>
+Date: Mon Oct 17 11:50:30 CEST 2011
+
+There's a lock inversion between the cputimer->lock and rq->lock; notably
+the two callchains involved are:
+
+ update_rlimit_cpu()
+   sighand->siglock
+   set_process_cpu_timer()
+     cpu_timer_sample_group()
+       thread_group_cputimer()
+         cputimer->lock
+         thread_group_cputime()
+           task_sched_runtime()
+             ->pi_lock
+             rq->lock
+
+ scheduler_tick()
+   rq->lock
+   task_tick_fair()
+     update_curr()
+       account_group_exec()
+         cputimer->lock
+
+Where the first one is enabling a CLOCK_PROCESS_CPUTIME_ID timer, and
+the second one is keeping up-to-date.
+
+This problem was introduced by e8abccb7193 ("posix-cpu-timers: Cure
+SMP accounting oddities").
+
+Cure the problem by removing the cputimer->lock and rq->lock nesting,
+this leaves concurrent enablers doing duplicate work, but the time
+wasted should be on the same order otherwise wasted spinning on the
+lock and the greater-than assignment filter should ensure we preserve
+monotonicity.
+
+Reported-by: Dave Jones <davej@redhat.com>
+Reported-by: Simon Kirby <sim@hostway.ca>
+Cc: stable@kernel.org
+Cc: Thomas Gleixner <tglx@linutronix.de>
+Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
+---
+ kernel/posix-cpu-timers.c |    7 ++++---
+ 1 file changed, 4 insertions(+), 3 deletions(-)
+Index: linux-2.6/kernel/posix-cpu-timers.c
+===================================================================
+--- linux-2.6.orig/kernel/posix-cpu-timers.c
+++ linux-2.6/kernel/posix-cpu-timers.c
+@@ -274,9 +274,7 @@ void thread_group_cputimer(struct task_s
+ 	struct task_cputime sum;
+ 	unsigned long flags;
+ 
+-	spin_lock_irqsave(&cputimer->lock, flags);
+ 	if (!cputimer->running) {
+-		cputimer->running = 1;
+ 		/*
+ 		 * The POSIX timer interface allows for absolute time expiry
+ 		 * values through the TIMER_ABSTIME flag, therefore we have
+@@ -284,8 +282,11 @@ void thread_group_cputimer(struct task_s
+ 		 * it.
+ 		 */
+ 		thread_group_cputime(tsk, &sum);
+		spin_lock_irqsave(&cputimer->lock, flags);
+		cputimer->running = 1;
+ 		update_gt_cputime(&cputimer->cputime, &sum);
+-	}
+	} else
+		spin_lock_irqsave(&cputimer->lock, flags);
+ 	*times = cputimer->cputime;
+ 	spin_unlock_irqrestore(&cputimer->lock, flags);
+ }
+
--- a/kernel.spec
+++ b/kernel.spec
@ -42,7 +42,7 @@ Summary: The Linux kernel
 # When changing real_sublevel below, reset this by hand to 1
 # (or to 0 and then use rpmdev-bumpspec).
 #
-%global baserelease 0
+%global baserelease 1
 %global fedora_build %{baserelease}

 # real_sublevel is the 3.x kernel version we're starting with
@ -649,6 +649,7 @@ Patch12016: disable-i8042-check-on-apple-mac.patch
 Patch12023: ums-realtek-driver-uses-stack-memory-for-DMA.patch
 Patch12024: usb-add-quirk-for-logitech-webcams.patch
 Patch12025: crypto-register-cryptd-first.patch
+Patch12026: cputimer-Cure-lock-inversion.patch

 # Runtime power management
 Patch12203: linux-2.6-usb-pci-autosuspend.patch
@ -1240,6 +1241,7 @@ ApplyPatch add-appleir-usb-driver.patch
 ApplyPatch ums-realtek-driver-uses-stack-memory-for-DMA.patch
 ApplyPatch usb-add-quirk-for-logitech-webcams.patch
 ApplyPatch crypto-register-cryptd-first.patch
+ApplyPatch cputimer-Cure-lock-inversion.patch

 # rhbz#605888
 ApplyPatch dmar-disable-when-ricoh-multifunction.patch
@ -1908,6 +1910,9 @@ fi
 # and build.

 %changelog
+* Tue Oct 18 2011 Josh Boyer <jwboyer@redhat.com>
+- Add patch to fix lock inversion introduced in 3.0.7
+
 * Mon Oct 17 2011 Josh Boyer <jwboyer@redhat.com> 2.6.40.7-0
 - Linux 3.0.7 stable release
 - Add two patches to fix stalls in khugepaged (rhbz 735946)