Re: [PATCH] mm: memory hotplug: Check if pages are correctly reserved on a per-section basis

Greg KH
2011-10-10T23:37:07Z

On Mon, Oct 10, 2011 at 04:28:13PM -0700, Andrew Morton wrote:
> On Mon, 10 Oct 2011 16:24:03 -0700
> Greg KH <greg@kroah.com> wrote:
>
> > On Mon, Oct 10, 2011 at 03:00:38PM -0700, Andrew Morton wrote:
> > > On Mon, 10 Oct 2011 08:11:19 +0100
> > > Mel Gorman <mgorman@suse.de> wrote:
> > >
> > > > It is expected that memory being brought online is PageReserved
> > > > similar to what happens when the page allocator is being brought up.
> > > > Memory is onlined in "memory blocks" which consist of one or more
> > > > sections. Unfortunately, the code that verifies PageReserved is
> > > > currently assuming that the memmap backing all these pages is virtually
> > > > contiguous which is only the case when CONFIG_SPARSEMEM_VMEMMAP is set.
> > > > As a result, memory hot-add is failing on !VMEMMAP configurations
> > > > with the message;
> > > >
> > > > kernel: section number XXX page number 256 not reserved, was it already online?
> > > >
> > > > This patch updates the PageReserved check to lookup struct page once
> > > > per section to guarantee the correct struct page is being checked.
> > > >
> > >
> > > Nathan's earlier version of this patch is already in linux-next, via
> > > Greg. We should drop the old version and get the new one merged
> > > instead.
> >
> > Ok, care to send me what exactly needs to be reverted and what needs to
> > be added?
>
> Drop
>
> commit 54f23eb7ba7619de85d8edca6e5336bc33072dbd
> Author: Nathan Fontenot <nfont@austin.ibm.com>
> Date: Mon Sep 26 10:22:33 2011 -0500
>
> memory hotplug: Correct page reservation checking
>
> and replace it with start-of-this-thread.
>
> That's assuming that Mel's update passes Nathan's review and testing :)

Ok, I'll wait for that review and testing, and then can someone send me
the patch at the start-of-this-thread as I no longer seem to be able to
find it :(

greg k-h