linux-kernel - Re: [PATCH] ring-buffer: Add set/clear_current_oom

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Message-ID: <CAJWu+ooTV+VYib6aDXc9V2As6Nzz5DddBttaxYxyMJd0ZrcwDA@mail.gmail.com>
Date:   Thu, 5 Apr 2018 16:36:37 -0700
From:   Joel Fernandes <joelaf@...gle.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...nel.org>,
        Zhaoyang Huang <huangzhaoyang@...il.com>,
        Ingo Molnar <mingo@...nel.org>,
        kernel-patch-test@...ts.linaro.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        "open list:MEMORY MANAGEMENT" <linux-mm@...ck.org>,
        Vlastimil Babka <vbabka@...e.cz>
Subject: Re: [PATCH] ring-buffer: Add set/clear_current_oom_origin() during allocations

Hi Steve,

On Thu, Apr 5, 2018 at 12:57 PM, Joel Fernandes <joelaf@...gle.com> wrote:
> On Thu, Apr 5, 2018 at 6:43 AM, Steven Rostedt <rostedt@...dmis.org> wrote:
>> On Wed, 4 Apr 2018 16:59:18 -0700
>> Joel Fernandes <joelaf@...gle.com> wrote:
>>
>>> Happy to try anything else, BTW when the si_mem_available check
>>> enabled, this doesn't happen and the buffer_size_kb write fails
>>> normally without hurting anything else.
>>
>> Can you remove the RETRY_MAYFAIL and see if you can try again? It may
>> be that we just remove that, and if si_mem_available() is wrong, it
>> will kill the process :-/ My original code would only add MAYFAIL if it
>> was a kernel thread (which is why I created the mflags variable).
>
> Tried this. Dropping RETRY_MAYFAIL and the si_mem_available check
> destabilized the system and brought it down (along with OOM killing
> the victim).
>
> System hung for several seconds and then both the memory hog and bash
> got killed.

I think its still Ok to keep the OOM patch as a safe guard even though
its hard to test, and the si_mem_available on its own seem sufficient.
What do you think?

thanks,


- Joel