linux-kernel - Re: [PATCH 2/5] mm/vmalloc: Extend __alloc_vmap

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Message-ID: <CA+KHdyXMhH1uf92Pv_6H1Qar4BsTdfykdr3jC=KwG8Fe6Je=PQ@mail.gmail.com>
Date:   Tue, 7 Jun 2022 15:02:42 +0200
From:   Uladzislau Rezki <urezki@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Nicholas Piggin <npiggin@...il.com>,
        Oleksiy Avramchenko <oleksiy.avramchenko@...y.com>
Subject: Re: [PATCH 2/5] mm/vmalloc: Extend __alloc_vmap_area() with extra arguments

>
> On Tue, Jun 07, 2022 at 11:34:46AM +0200, Uladzislau Rezki (Sony) wrote:
> > It implies that __alloc_vmap_area() allocates only from the
> > global vmap space, therefore a list-head and rb-tree, which
> > represent a free vmap space, are not passed as parameters to
> > this function and are accessed directly from this function.
>
> Yes, which totally makes sense.
>
> > Extend the __alloc_vmap_area() and other dependent functions
> > to have a possibility to allocate from different trees making
> > an interface common and not specific.
>
> Which seems completely pointless.  Why add argument that are always
> passed the same values?
>
I wrote about it in the cover latter. It is a preparation work for
making vmalloc per-cpu.
In that case free/busy data are located on different rb_roots that is
why those functions
have to be adopted to work with any tree.

-- 
Uladzislau Rezki