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Date: Thu, 26 Apr 2018 21:49:19 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [dm-devel] [PATCH v5] fault-injection: introduce kvmalloc
 fallback options
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To: Mikulas Patocka <mpatocka@redhat.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>, Michal Hocko <mhocko@kernel.org>, David Rientjes <rientjes@google.com>, dm-devel@redhat.com, eric.dumazet@gmail.com, netdev@vger.kernel.org, jasowang@redhat.com, Randy Dunlap <rdunlap@infradead.org>, linux-kernel@vger.kernel.org, Matthew Wilcox <willy@infradead.org>, linux-mm@kvack.org, edumazet@google.com, Andrew Morton <akpm@linux-foundation.org>, virtualization@lists.linux-foundation.org, David Miller <davem@davemloft.net>, Vlastimil Babka <vbabka@suse.cz>

On Thu, Apr 26, 2018 at 12:07:25PM -0400, Mikulas Patocka wrote:
> > IIUC debug kernels mainly exist so people who experience e.g. memory
> > corruption can try and debug the failure. In this case, CONFIG_DEBUG_SG
> > will *already* catch a failure early. Nothing special needs to be done.
> 
> The patch helps people debug such memory coprruptions (such as using DMA 
> API on the result of kvmalloc).

That's my point.  I don't think your patch helps debug any memory
corruptions.  With CONFIG_DEBUG_SG using DMA API already causes a
BUG_ON, that's before any memory can get corrupted.

-- 
MST