linux-kernel - Re: Page Allocation Failure and Page allocation stalls

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Message-ID: <CACDBo56LBKsxqsHAi=Jd6ZJoZsSpFJ5a_DbwEx9h+=FJjr0rhw@mail.gmail.com>
Date:   Thu, 9 May 2019 22:17:14 +0530
From:   Pankaj Suryawanshi <pankajssuryawanshi@...il.com>
To:     Vlastimil Babka <vbabka@...e.cz>
Cc:     Valdis Klētnieks <valdis.kletnieks@...edu>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        kernelnewbies@...nelnewbies.org, Michal Hocko <mhocko@...nel.org>,
        minchan@...nel.org
Subject: Re: Page Allocation Failure and Page allocation stalls

On Mon, May 6, 2019 at 2:35 PM Vlastimil Babka <vbabka@...e.cz> wrote:
>
> On 5/3/19 7:44 PM, Pankaj Suryawanshi wrote:
> >> First possibility that comes to mind is that a usermodehelper got launched, and
> >> it then tried to fork with a very large active process image.  Do we have any
> >> clues what was going on?  Did a device get hotplugged?
> >
> > Yes,The system is android and it tries to allocate memory for video
> > player from CMA reserved memory using custom octl call for dma apis.
>
> The stacktrace doesn't look like a CMA allocation though. That would be
> doing alloc_contig_range(), not kmalloc(). Could be some CMA area setup
> issue?
>
I know cma uses alloc_contig_range() but using dma api it will uses
many functions.
the failure is coming from dma_common_contiguous_remap() for kmalloc ,
and which is called by dma_alloc_attr for cma allocation.

Please let me know, how to avoid page allocation stalls. any reason ?
Cpu Utilization issue ? or I am running out of memory ?

My System configuration is
2GB RAM
Memory Spilt 2G/2G
vmalloc=1024M
CMA=1024
Max contiguous memory required 390M

> > Please let me know how to overcome this issues, or how to reduce
> > fragmentation of memory so that higher order allocation get suuceed ?
> >
> > Thanks
> >
>