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Message-ID: <1540981182.16084.1.camel@mtkswgap22>
Subject: Re: [PATCH v3] mm/page_owner: use kvmalloc instead of kmalloc
From: Miles Chen <miles.chen@mediatek.com>
Date: Wed, 31 Oct 2018 18:19:42 +0800
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To: Michal Hocko <mhocko@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>, Joe Perches <joe@perches.com>, Matthew Wilcox <willy@infradead.org>, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, wsd_upstream@mediatek.com

On Wed, 2018-10-31 at 11:15 +0100, Michal Hocko wrote:
> On Wed 31-10-18 16:47:17, Miles Chen wrote:
> > On Tue, 2018-10-30 at 09:15 +0100, Michal Hocko wrote:
> > > On Tue 30-10-18 14:55:51, Miles Chen wrote:
> > > [...]
> > > > It's a real problem when using page_owner.
> > > > I found this issue recently: I'm not able to read page_owner information
> > > > during a overnight test. (error: read failed: Out of memory). I replace
> > > > kmalloc() with vmalloc() and it worked well.
> > > 
> > > Is this with trimming the allocation to a single page and doing shorter
> > > than requested reads?
> > 
> > 
> > I printed out the allocate count on my device the request count is <=
> > 4096. So I tested this scenario by trimming the count to from 4096 to
> > 1024 bytes and it works fine. 
> > 
> > count = count > 1024? 1024: count;
> > 
> > It tested it on both 32bit and 64bit kernel.
> 
> Are you saying that you see OOMs for 4k size?
> 
yes, because kmalloc only use normal memor, not highmem + normal memory
I think that's why vmalloc() works.