linux-kernel - Re: [PATCH 2/6] lib/rhashtable: guarantee initial hashtable allocation

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Message-ID: <20180530142906.fdib4dw2ik6smduu@linux-r8p5>
Date:   Wed, 30 May 2018 07:29:06 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     Herbert Xu <herbert@...dor.apana.org.au>
Cc:     akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
        tgraf@...g.ch, manfred@...orfullife.com,
        guillaume.knispel@...ersonicimagine.com, linux-api@...r.kernel.org,
        linux-kernel@...r.kernel.org, Davidlohr Bueso <dbueso@...e.de>
Subject: Re: [PATCH 2/6] lib/rhashtable: guarantee initial hashtable
 allocation

On Wed, 30 May 2018, Herbert Xu wrote:

>On Tue, May 29, 2018 at 10:59:27AM -0700, Davidlohr Bueso wrote:
>That's exactly what you need to explain in the patch or the commit
>message.  In fact you still haven't explained it fully.  Why do we
>need a second attempt without the GFP_NOFAIL? How does it help the
>allocator?

It helps in that we have two fastpath attempts before going in to
__alloc_pages_slowpath() and looping in __GFP_NOFAIL. But yeah, I
see your point. We can just apply KISS and avoid the extra alloc.
That actually makes more sense to me now than ignoring min_size
based on simplicity.

Thanks for the review.

Thanks,
Davidlohr