Re: 2.6.24-rc5-mm1 -- inconsistent {in-hardirq-W} -> {hardirq-on-W} usage -- pm-hibernate/9940 [HC0[0]:SC0[0]:HE1:SE1]

From: Rafael J. Wysocki
Date: Wed Dec 19 2007 - 18:10:21 EST


On Wednesday, 19 of December 2007, Christoph Lameter wrote:
> On Wed, 19 Dec 2007, Daniel Walker wrote:
>
> > > It looks like the swsusp_save() calls drain_all_pages() , which calls
> > > on_each_cpu() .. On return on_each_cpu() unconditionally enables
> > > interrupts so the rest of the resume process has interrupt enable
> > > (which , it looks like, shouldn't happen) and then you get the lockdep()
> > > warning due to the above..
> > >
> > > Not sure if this has been found already, or not?
>
> Hmmm... It will unconditionally enable interrupts regardless how we call
> this. We could explicity save and restore interrrupts in
> swsusp_save() I guess. Why is swsusp_save() disabling interrupts?

Actually, it's called with interrupts disabled, because it's job is to create
the hibernation image. At this point everything is off except for the CPU
running swsusp_save().

> > > Should drain_all_pages() really be drain_local_pages() ?
> >
> > It looks like it was drain_local_pages, but the following patch
> >
> > page-allocator-clean-up-pcp-draining-functions.patch
> >
> > Changes that in -mm .. I added Christoph Lameter to the CC since it's
> > his patch ..
>
> We could reexport drain_local_pages() again but then I do not understand
> why we would only drain the pages of this processor and not of all other
> processors as well. It seems that software suspend intend was to flush
> them all right?

Well, not exactly. We are on one CPU at this point, the others have been
disabled.
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