linux-kernel - Re: [PATCH v2 3/4] mm/shmem, swap: improve mthp swapin process

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Message-ID: <e7b6b4bd-5294-4fe9-bcc6-225013e7828c@linux.alibaba.com>
Date: Mon, 23 Jun 2025 11:37:24 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Kairui Song <kasong@...cent.com>, linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>, Hugh Dickins
 <hughd@...gle.com>, Matthew Wilcox <willy@...radead.org>,
 Kemeng Shi <shikemeng@...weicloud.com>, Chris Li <chrisl@...nel.org>,
 Nhat Pham <nphamcs@...il.com>, Baoquan He <bhe@...hat.com>,
 Barry Song <baohua@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 3/4] mm/shmem, swap: improve mthp swapin process

Hi Kairui,

On 2025/6/20 01:55, Kairui Song wrote:
> From: Kairui Song <kasong@...cent.com>
> 
> Tidy up the mTHP swapin code, reduce duplicated codes and slightly
> tweak the workflow.
> 
> For SWP_SYNCHRONOUS_IO devices, we should skip the readahead and swap
> cache even if the swapin falls back to order 0. Readahead is not helpful
> for such devices.

Yes, agree.

> Also consolidates the mTHP related check to one place so they are now
> all wrapped by CONFIG_TRANSPARENT_HUGEPAGE, and will be trimmed off by
> compiler if not needed.

I like your idea. But I found this patch hard to review, since you you 
mixed too many changes into one patch. I think you could at least split 
it into 3 patches to make it easier for the reviewer to review and test:

1. consolidate the mTHP related check to one place (cleanup)
2. tidy up the mTHP swapin code (cleanup)
3. skip swapcache for order 0