linux-kernel - Re: [GIT PULL] MM updates for 6.5-rc1

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Date:   Wed, 28 Jun 2023 20:18:32 +0100
From:   David Howells <dhowells@...hat.com>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     dhowells@...hat.com, Andrew Morton <akpm@...ux-foundation.org>,
        Stephen Rothwell <sfr@...b.auug.org.au>, linux-mm@...ck.org,
        mm-commits@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [GIT PULL] MM updates for 6.5-rc1

Linus Torvalds <torvalds@...ux-foundation.org> wrote:

> Side note: I think we should just do the "FOLL_GET" doesn't touch the
> refcount either, which would make this all become just

Yeah... but there's a lot of places that would potentially need fixing.
iov_iter_get_pages*(), for example, is used to grab pages and push them to all
sorts of destinations, including pipes and sk_buffs.

> but then we would need to fix try_grab_page() and gup_put_folio() and
> friends to match. And any other cases I haven't thought of.

And put_page(), folio_put(), ...  I wonder if there would be a noticeable
performance loss from adding an is_zero_page() check into those.

It might also make sense to include the entire kernel post-init static image
in that, perhaps a check:

	if ((unsigned long)(virt_address) & KERNEL_MASK == KERNEL_BASE)
		return;

David