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Date: Thu, 1 Oct 2026 18:16:26 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Alexandre Ghiti <alex@ghiti.fr>, linux-mm@kvack.org, Christoph Hellwig
 <hch@lst.de>, Chris Li <chrisl@kernel.org>, Kairui Song
 <kasong@tencent.com>, Kemeng Shi <shikemeng@huaweicloud.com>, Nhat Pham
 <nphamcs@gmail.com>, Baoquan He <baoquan.he@linux.dev>, Barry Song
 <baohua@kernel.org>, Youngjun Park <youngjun.park@lge.com>,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/swap: submit the last readahead batch before
 unplugging
Message-Id: <20261001181626.b4aa4476f1b3649fd3e6d54e@linux-foundation.org>
In-Reply-To: <20261001095238.2417205-1-joshua.hahnjy@gmail.com>
References: <20261001085730.2029773-1-alex@ghiti.fr>
	<20261001095238.2417205-1-joshua.hahnjy@gmail.com>
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On Thu,  1 Oct 2026 02:52:33 -0700 Joshua Hahn <joshua.hahnjy@gmail.com> wrote:

> On Thu,  1 Oct 2026 10:57:12 +0200 Alexandre Ghiti <alex@ghiti.fr> wrote:
> 
> > Since block swap I/O is batched in struct swap_iocb, swap_add_folio()
> > only appends a folio to the pending batch when its slot directly follows
> > the previous one, and submits the pending batch otherwise. Batches
> > submitted inside the readahead loop go through the plug, where the block
> > layer can still merge them, but the final batch is submitted after
> > blk_finish_plug() and always becomes a separate request.
> > 
> > So submit the final batch before finishing the plug.
> 
> Hi Alex,
> 
> I read through the code and this looks very reasonable to me.
> 
> Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>

Thanks.

> > Fixes: dda8fb68b590 ("mm/swap: also use struct swap_iocb for block I/O")
> 
> My only question is whether we need the fixes tag, it seems like
> dda8fb68b590 is still in mm-stable and not merged to linus yet.
> 
> Andrew, what do we usually do in these cases? I am wondering if it will
> just become folded into the original commit or if this should still be
> standalone.

dda8fb68b590 was added to 7.3.rc1 during the most recent merge window.

So the Fixes: is appropriate - if someone chooses to merge dda8fb68b590
into their downstream kernel we're telling them "hey, you need this one
as well".