Re: [-rc7 regression] Buggy commit: "mm: use aligned zone start for pfn_to_bitidx calculation"

From: Greg KH <gregkh@linuxfoundation.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Yinghai Lu <yinghai@kernel.org>, Greg KH <gregkh@suse.de>,
	Thomas Gleixner <tglx@linutronix.de>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Jens Axboe <axboe@kernel.dk>,
	Alexander Viro <viro@ftp.linux.org.uk>,
	"Theodore Ts'o" <tytso@mit.edu>, "H. Peter Anvin" <hpa@zytor.com>,
	Laura Abbott <lauraa@codeaurora.org>,
	Mel Gorman <mgorman@suse.de>
Subject: Re: [-rc7 regression] Buggy commit: "mm: use aligned zone start for pfn_to_bitidx calculation"
Date: Fri, 1 Mar 2013 08:50:43 -0800	[thread overview]
Message-ID: <20130301165043.GB5435@kroah.com> (raw)
In-Reply-To: <20130216082954.GA18953@gmail.com>

On Sat, Feb 16, 2013 at 09:29:54AM +0100, Ingo Molnar wrote:
> 
> * Greg KH <greg@kroah.com> wrote:
> 
> > On Fri, Feb 15, 2013 at 12:44:26PM +0100, Ingo Molnar wrote:
> > > 
> > > [ Greg: -stable was Cc:-ed for this potentially buggy commit. ]
> > > 
> > > * Yinghai Lu <yinghai@kernel.org> wrote:
> > > 
> > > > On Thu, Feb 14, 2013 at 7:08 AM, Ingo Molnar <mingo@kernel.org> wrote:
> > > > > these three:
> > > > >
> > > > > 10d73e655cef mm: bootmem: fix free_all_bootmem_core() with odd bitmap alignment
> > > > > c060f943d092 mm: use aligned zone start for pfn_to_bitidx calculation
> > > > > c0232ae861df mm: memblock: fix wrong memmove size in memblock_merge_regions()
> > > > >
> > > > > might have highmem=512m boot parameter sensitivity.
> > > > 
> > > > 10d73e655cef should not be related, as we are using nobootmem wrapper
> > > > of memblock.
> > > > c0232ae861df is copying less while using the blank slot in memblock
> > > > memory or reserved array
> > > > so it should be ok too.
> > > > 
> > > > c060f943d092 may be related as you config does not have
> > > > CONFIG_SPARSEMEM defined.
> > > 
> > > Right, that's the commit causing the x86 regression:
> > > 
> > >  c060f943d0929f3e429c5d9522290584f6281d6e is the first bad commit
> > >  commit c060f943d0929f3e429c5d9522290584f6281d6e
> > >  Date:   Fri Jan 11 14:31:51 2013 -0800
> > > 
> > >      mm: use aligned zone start for pfn_to_bitidx calculation
> > > 
> > > I've given 6d92d4f (its parent commit) quite a bit of testing so 
> > > I'm 99% sure in the validity of this bisection result.
> > > 
> > > Involved parties Cc:-ed.
> > > 
> > > Revert attached below - it reverts cleanly and I'll test this 
> > > today, to see whether this solves the sporadic lockups.
> > > 
> > > Thanks,
> > > 
> > > 	Ingo
> > > 
> > > ------------------->
> > > >From 6f3d5a8f38eb23f792b408d9bc8fee53a7d158f9 Mon Sep 17 00:00:00 2001
> > > From: Ingo Molnar <mingo@kernel.org>
> > > Date: Fri, 15 Feb 2013 12:43:22 +0100
> > > Subject: [PATCH] Revert "mm: use aligned zone start for pfn_to_bitidx
> > >  calculation"
> > > 
> > > This reverts commit c060f943d0929f3e429c5d9522290584f6281d6e.
> > 
> > Let me know if I should be reverting this from the -stable releases.
> 
> It appears so - it definitely locks up here with the config I 
> sent. It appears to be a rare bug but a bug.
> 
> Would be nice to hear from the authors/ackers/pushers of the 
> patch though.

What ever happened with this?  Did something go into Linus's tree to
resolve this issue that I need to pull into a stable release?

thanks,

greg k-h