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Date: Thu, 24 Jul 2014 20:36:43 +0200 From: Peter Zijlstra <peterz@...radead.org> To: Linus Torvalds <torvalds@...ux-foundation.org> Cc: Borislav Petkov <bp@...en8.de>, Waiman Long <Waiman.Long@...com>, Ingo Molnar <mingo@...nel.org>, Linux Kernel Mailing List <linux-kernel@...r.kernel.org>, USB list <linux-usb@...r.kernel.org>, "linux-input@...r.kernel.org" <linux-input@...r.kernel.org> Subject: Re: Linux 3.16-rc6 On Thu, Jul 24, 2014 at 11:18:16AM -0700, Linus Torvalds wrote: > On Thu, Jul 24, 2014 at 5:58 AM, Peter Zijlstra <peterz@...radead.org> wrote: > > > > So going by the nifty picture rostedt made: > > > > [ 61.454336] CPU0 CPU1 > > [ 61.454336] ---- ---- > > [ 61.454336] lock(&(&p->alloc_lock)->rlock); > > [ 61.454336] local_irq_disable(); > > [ 61.454336] lock(tasklist_lock); > > [ 61.454336] lock(&(&p->alloc_lock)->rlock); > > [ 61.454336] <Interrupt> > > [ 61.454336] lock(tasklist_lock); > > So this *should* be fine. It always has been in the past, and it was > certainly the *intention* that it should continue to work with > qrwlock, even in the presense of pending writers on other cpu's. > > The qrwlock rules are that a read-lock in an interrupt is still going > to be unfair and succeed if there are other readers. Ah, indeed. Should have checked :/ > So it sounds to me like the new lockdep rules in tip/master are too > strict and are throwing a false positive. Right. Waiman can you have a look? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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