linux-kernel - Re: Kernel 4.1.6 Panic due to slab corruption

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Date:	Tue, 8 Sep 2015 09:27:58 -0500 (CDT)
From:	Christoph Lameter <cl@...ux.com>
To:	Nikolay Borisov <kernel@...p.com>
cc:	"Linux-Kernel@...r. Kernel. Org" <linux-kernel@...r.kernel.org>,
	Marian Marinov <mm@...com>,
	SiteGround Operations <operations@...eground.com>
Subject: Re: Kernel 4.1.6 Panic due to slab corruption

On Tue, 8 Sep 2015, Nikolay Borisov wrote:

> Unfortunately I haven't found a way to reproduce it so the only option
> would be to do this on a live server. However, the performance impact I
> believe is going to be very prohibitive :(.  Alternatively what I could
> do is probably leave merging on but enable debugging only for the
> kmalloc-32 slab cache. Do you think this would provide enough
> information to help track the corruption when it happens, without
> impacting performance?

You have read https://www.kernel.org/doc/Documentation/vm/slub.txt?


The problem now is that merging is on so it could be that the corruption
happens in one of the aliased caches. So maybe only kmalloc-32 wont do
much good.

Run

	slabinfo -a

(slabinfo.c is a tool in the kernel tree.)

to see the list of aliases for kmalloc-32.

You can also use slabinfo to enable some debugging at runtime. Just
enabling sanity checks may catch something that allows us to track this to
the subsystem.





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