linux-kernel - Re: [PATCH 0/3] Early use of boot service memory

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20131118153211.GB32168@redhat.com>
Date:	Mon, 18 Nov 2013 10:32:11 -0500
From:	Vivek Goyal <vgoyal@...hat.com>
To:	Yinghai Lu <yinghai@...nel.org>
Cc:	"H. Peter Anvin" <hpa@...or.com>, Ingo Molnar <mingo@...nel.org>,
	jerry.hoemann@...com, Pekka Enberg <penberg@...nel.org>,
	Rob Landley <rob@...dley.net>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	x86 maintainers <x86@...nel.org>,
	Matt Fleming <matt.fleming@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"list@...ederm.org:DOCUMENTATION" <linux-doc@...r.kernel.org>,
	"list@...ederm.org:MEMORY MANAGEMENT" <linux-mm@...ck.org>,
	linux-efi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 0/3] Early use of boot service memory

On Fri, Nov 15, 2013 at 02:24:25PM -0800, Yinghai Lu wrote:
> On Fri, Nov 15, 2013 at 10:03 AM, Vivek Goyal <vgoyal@...hat.com> wrote:
> > On Fri, Nov 15, 2013 at 09:33:41AM -0800, Yinghai Lu wrote:
> 
> >> I have one system with 6TiB memory, kdump does not work even
> >> crashkernel=512M in legacy mode. ( it only work on system with
> >> 4.5TiB).
> >
> > Recently I tested one system with 6TB of memory and dumped successfully
> > with 512MB reserved under 896MB. Also I have heard reports of successful
> > dump of 12TB system with 512MB reserved below 896MB (due to cyclic
> > mode of makedumpfile).
> >
> > So with newer releases only reason one might want to reserve more
> > memory is that it might provide speed benefits. We need more testing
> > to quantify this.
> 
> You may need bunch of PCIe cards installed.
> 
> The system with 6TiB + 16 PCIe cards, second kernel OOM.
> The system with 4.5TiB + 16 PCIe cards, second kernel works with vmcore dumped.

What's the distro you are testing with? Do you have latest bits of
makeudmpfile where we use cyclic mode by default and one does not need
more reserved memory because of more physical memory present in the
box. I suspect that might be the problem in your testing environment
and old makedumpfile wil try to allocate larger memory on large
RAM machines and OOM.

[..]
> > So issue remains that crashkernel=X,high is not a good default choice
> > because it consumes extra 72M which we don't have to.
> 
> then if it falls into 896~4G, user may still need to update kexec-tools ?

Yep. But distributions control the version of kexec-tools and version
of kernel and can ship updated kexec-tools by default.

Thanks
Vivek
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/