linux-kernel - Re: [RFC PATCH 0/2] remove SWAP_MAP

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Message-ID: <CAGsJ_4xe_Cz=+tEpX5uu5KVXa61e2D6U2pFvU5MhwUeZo2CD_g@mail.gmail.com>
Date: Wed, 25 Sep 2024 15:38:37 +0800
From: Barry Song <21cnbao@...il.com>
To: "Huang, Ying" <ying.huang@...el.com>
Cc: Yosry Ahmed <yosryahmed@...gle.com>, Nhat Pham <nphamcs@...il.com>, 
	Baolin Wang <baolin.wang@...ux.alibaba.com>, akpm@...ux-foundation.org, 
	hannes@...xchg.org, hughd@...gle.com, shakeel.butt@...ux.dev, 
	ryan.roberts@....com, chrisl@...nel.org, david@...hat.com, kasong@...cent.com, 
	willy@...radead.org, viro@...iv.linux.org.uk, chengming.zhou@...ux.dev, 
	linux-mm@...ck.org, kernel-team@...a.com, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 0/2] remove SWAP_MAP_SHMEM

On Wed, Sep 25, 2024 at 3:28 PM Huang, Ying <ying.huang@...el.com> wrote:
>
> Barry Song <21cnbao@...il.com> writes:
>
> [snip]
>
> > I am perfectly fine with the approach, in the first loop, if we find all entries
> > don't need CONTINUED, we can run the 2nd loop even for usage==1
> > and nr > 1. this is almost always true for a real product where anon folios
> > are unlikely to be fork-shared by so many processes.
>
> One possible use case is ksm.  Where the map count could be large.

Sorry, I overlooked the KSM case, but it seems this doesn't significantly
change the overall direction. :-)

Since we can fall back to swap_duplicate() and handle each entry one
by one after the first loopback returns -ENOMEM, KSM isn't a concern
either.

>
> --
> Best Regards,
> Huang, Ying

Thanks
Barry