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

From: Greg KH <greg@kroah.com>
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, 15 Feb 2013 14:06:15 -0800	[thread overview]
Message-ID: <20130215220615.GA1696@kroah.com> (raw)
In-Reply-To: <20130215114425.GD26955@gmail.com>

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.

thanks,

greg k-h