Johannes Weiner wrote:
> On Tue, Feb 02, 2016 at 10:33:22PM +0900, Tetsuo Handa wrote:
> > >From 20b3c1c9ef35547395c3774c6208a867cf0046d4 Mon Sep 17 00:00:00 2001
> > From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
> > Date: Tue, 2 Feb 2016 16:50:45 +0900
> > Subject: [RFC][PATCH] mm, page_alloc: Warn on !__GFP_NOWARN allocation from IRQ context.
> >
> > Jan Stancek hit a hard lockup problem due to flood of memory allocation
> > failure messages which lasted for 10 seconds with IRQ disabled. Printing
> > traces using warn_alloc_failed() is very slow (which can take up to about
> > 1 second for each warn_alloc_failed() call). The caller used GFP_NOWARN
s/GFP_NOWARN/GFP_NOWAIT/
> > inside a loop. If the caller used __GFP_NOWARN, it would not have lasted
> > for 10 seconds.
>
> Who is doing page allocations in a loop with irqs disabled?!
lib/dma-debug.c functions which are called with irqs disabled.
http://lkml.kernel.org/r/201601292135.DHG60988.SOQFJFOHFVMLOt@xxxxxxxxxxxxxxxxxxx
>
> And then, why does it take that long? Is that a serial console? Most
> of the output is KERN_INFO, it might be better to raise the loglevel
> and still have all the debugging output in the logs.
Yes, I think it is a serial console.
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