linux-kernel - Re: [PATCH 0/6 v3] kvmalloc

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Date:   Mon, 30 Jan 2017 17:15:08 +0100
From:   Daniel Borkmann <daniel@...earbox.net>
To:     Michal Hocko <mhocko@...nel.org>
CC:     Alexei Starovoitov <alexei.starovoitov@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Vlastimil Babka <vbabka@...e.cz>, Mel Gorman <mgorman@...e.de>,
        Johannes Weiner <hannes@...xchg.org>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        marcelo.leitner@...il.com
Subject: Re: [PATCH 0/6 v3] kvmalloc

On 01/30/2017 08:56 AM, Michal Hocko wrote:
> On Fri 27-01-17 21:12:26, Daniel Borkmann wrote:
>> On 01/27/2017 11:05 AM, Michal Hocko wrote:
>>> On Thu 26-01-17 21:34:04, Daniel Borkmann wrote:
> [...]
>>>> So to answer your second email with the bpf and netfilter hunks, why
>>>> not replacing them with kvmalloc() and __GFP_NORETRY flag and add that
>>>> big fat FIXME comment above there, saying explicitly that __GFP_NORETRY
>>>> is not harmful though has only /partial/ effect right now and that full
>>>> support needs to be implemented in future. That would still be better
>>>> that not having it, imo, and the FIXME would make expectations clear
>>>> to anyone reading that code.
>>>
>>> Well, we can do that, I just would like to prevent from this (ab)use
>>> if there is no _real_ and _sensible_ usecase for it. Having a real bug
>>
>> Understandable.
>>
>>> report or a fallback mechanism you are mentioning above would justify
>>> the (ab)use IMHO. But that abuse would be documented properly and have a
>>> real reason to exist. That sounds like a better approach to me.
>>>
>>> But if you absolutely _insist_ I can change that.
>>
>> Yeah, please do (with a big FIXME comment as mentioned), this originally
>> came from a real bug report. Anyway, feel free to add my Acked-by then.
>
> Thanks! I will repost the whole series today.

Looks like I got only Cc'ed on the cover letter of your v3 from today
(should have been v4 actually?). Anyway, I looked up the last patch
on lkml [1] and it seems you forgot the __GFP_NORETRY we talked about?
At least that was what was discussed above (insisting on __GFP_NORETRY
plus FIXME comment) for providing my Acked-by then. Can you still fix
that up in a final respin?

Thanks again,
Daniel

   [1] https://lkml.org/lkml/2017/1/30/129