linux-kernel - Re: [dm-devel] [v2 PATCH 0/5] Introduce mempool pages bulk allocator and use it in dm-crypt

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Date:   Wed, 15 Feb 2023 07:23:37 -0500 (EST)
From:   Mikulas Patocka <mpatocka@...hat.com>
To:     Yang Shi <shy828301@...il.com>
cc:     mgorman@...hsingularity.net, agk@...hat.com, snitzer@...nel.org,
        dm-devel@...hat.com, akpm@...ux-foundation.org,
        linux-block@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [dm-devel] [v2 PATCH 0/5] Introduce mempool pages bulk allocator
 and use it in dm-crypt

On Tue, 14 Feb 2023, Yang Shi wrote:

> 
> Changelog:
> RFC -> v2:
>   * Added callback variant for page bulk allocator and mempool bulk allocator
>     per Mel Gorman.
>   * Used the callback version in dm-crypt driver.
>   * Some code cleanup and refactor to reduce duplicate code.
> 
> rfc: https://lore.kernel.org/linux-mm/20221005180341.1738796-1-shy828301@gmail.com/

Hi

This seems like unneeded complication to me. We have alloc_pages(), it can 
allocate multiple pages efficiently, so why not use it?

I suggest to modify crypt_alloc_buffer() to use alloc_pages() and if 
alloc_pages() fails (either because the system is low on memory or because 
memory is too fragmented), fall back to the existing code that does 
mempool_alloc().

Mikulas