Re: patch "devres: Align data[] to ARCH_KMALLOC_MINALIGN" added to driver-core-linus

["gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>]

On Thu, Feb 07, 2019 at 01:12:43PM +0000, Alexey Brodkin wrote:
> Hi Greg,
> 
> > -----Original Message-----
> > From: gregkh@linuxfoundation.org <gregkh@linuxfoundation.org>
> > Sent: Sunday, November 11, 2018 10:41 PM
> > To: alexey.brodkin@synopsys.com; David.Laight@ACULAB.COM; alexey.brodkin@synopsys.com; geert@linux-
> > m68k.org; greg@kroah.com; gregkh@linuxfoundation.org; peterz@infradead.org; stable@vger.kernel.org;
> > tglx@linutronix.de; vineet.gupta1@synopsys.com; will.deacon@arm.com
> > Subject: patch "devres: Align data[] to ARCH_KMALLOC_MINALIGN" added to driver-core-linus
> > 
> > 
> > This is a note to let you know that I've just added the patch titled
> > 
> >     devres: Align data[] to ARCH_KMALLOC_MINALIGN
> > 
> > to my driver-core git tree which can be found at
> >     git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
> > in the driver-core-linus branch.
> > 
> > The patch will show up in the next release of the linux-next tree
> > (usually sometime within the next 24 hours during the week.)
> > 
> > The patch will hopefully also be merged in Linus's tree for the
> > next -rc kernel release.
> > 
> > If you have any questions about this process, please let me know.
> > 
> > 
> > From a66d972465d15b1d89281258805eb8b47d66bd36 Mon Sep 17 00:00:00 2001
> > From: Alexey Brodkin <alexey.brodkin@synopsys.com>
> > Date: Wed, 31 Oct 2018 18:25:47 +0300
> > Subject: devres: Align data[] to ARCH_KMALLOC_MINALIGN
> > 
> > Initially we bumped into problem with 32-bit aligned atomic64_t
> > on ARC, see [1]. And then during quite lengthly discussion Peter Z.
> > mentioned ARCH_KMALLOC_MINALIGN which IMHO makes perfect sense.
> > If allocation is done by plain kmalloc() obtained buffer will be
> > ARCH_KMALLOC_MINALIGN aligned and then why buffer obtained via
> > devm_kmalloc() should have any other alignment?
>  
> [snip]
> 
> > Cc: <stable@vger.kernel.org> # 4.8+
> > Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> I noticed this patch was not only merged in Linus' tree quite some time ago
> but it was as well back-ported to v4.20, see [1] but for some reason there's
> no backport to either LTS kernel (v4.19, v4.14 and v4.9).
> 
> Is there any problem with this patch and LTS kernels or may we have this one
> applied?
> 
> [1] https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=linux-4.20.y&id=a66d972465d15b1d89281258805eb8b47d66bd36

Ah, I was waiting to see if you would notice :)

See this question from Linus about this patch:
	https://lore.kernel.org/lkml/CAHk-=wj3Q7CkMQYwfZSsqUTqkEhNwVGrRbCwe7AVJ70S8i5sWw@mail.gmail.com/

I figured that you all did this for a good reason, and wasting that much
space was going to be ok.  But, I wanted to be sure, so if you never
noticed it, I figured it was not that pressing of an issue.

Anyway, is this really needed to be backported?

thanks,

greg k-h