linux-kernel - Re: [PATCH 2/3] staging: lustre: lnet: Allocate MEs and small MDs in own kmem

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Message-ID: <20160610012833.GA6804@kroah.com>
Date:	Thu, 9 Jun 2016 18:28:33 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	James Simmons <jsimmons@...radead.org>
Cc:	devel@...verdev.osuosl.org,
	Andreas Dilger <andreas.dilger@...el.com>,
	Oleg Drokin <oleg.drokin@...el.com>,
	Bruno Faccini <bruno.faccini@...el.com>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Lustre Development List <lustre-devel@...ts.lustre.org>
Subject: Re: [PATCH 2/3] staging: lustre: lnet: Allocate MEs and small MDs in
 own kmem_caches

On Thu, Jun 09, 2016 at 06:45:46PM -0400, James Simmons wrote:
> From: Bruno Faccini <bruno.faccini@...el.com>
> 
> As part of LU-3848 and LU-4330, it has been discovered that LNET
> MEs and small MDs (<=128 Bytes) are allocated in <size-128> kmem_cache
> and thus can suffer quite frequent corruptions, from other modules or
> Kernel parts, that occur there. To avoid this, MEs and small-MDs
> specific kmem_cache have been created.

What?  Who corrupts them?  That shouldn't be possible, and on some
systems, even if you do ask for a separate slab, it will be merged
togther with others of the same size.  So this patch doesn't do all that
much.

I think you are having some other problem here, changing to a separate
memory cache shouldn't solve corruption issues.

sorry,

greg k-h