On 22.11.24 06:42, Andrew Morton wrote:
On Tue, 19 Nov 2024 04:35:47 +0000 Matthew Wilcox <willy@xxxxxxxxxxxxx> wrote:
On Mon, Nov 18, 2024 at 07:30:01PM -0800, Andrew Morton wrote:
Matthew Wilcox (Oracle) (13):
ksm: use a folio in try_to_merge_one_page()
ksm: convert cmp_and_merge_page() to use a folio
Unfortunately you left the crap patch in from Gaosheng. Linus, can you
apply this fixup?
>From 3d7e7319bbb3ced1dfb9c82bb7e8c7386380799b Mon Sep 17 00:00:00 2001
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Date: Mon, 18 Nov 2024 23:32:25 -0500
Subject: [PATCH] mm: Revert IS_ERR_OR_NULL check
&foo->bar is address arithmetic, not a dereference of foo.
Huawei engineers seem particularly prone to not knowing this.
It isn't only Huawai people. David acked Gaosheng's patch and it snuck
past me (again). People keep on getting tricked by this idiom and I
think we'd be better off with some nicely named wrapper to help
readers understand what's going on.
The helper we have is "folio_page(folio, 0)" ... and we do have a bunch
of that usage in the kernel.
Likely we, want a more catchy helper that simply gives us the first (and
for small folios the only) page.
... not able to come up with good names though. folio_page0(),
folio_first_page(), ... :(
Once folios no longer overlay pages, the &folio->page trick will stop
working I guess, and I recall a comment from Willy about that.
... and then we'd probably have to dereference the folio to obtain the
"struct page"?
--
Cheers,
David / dhildenb
