Re: [PATCH v3] mm/page_owner: use kvmalloc instead of kmalloc

[Miles Chen]

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.