From: Matthew Wilcox <willy@infradead.org>
To: Breno Leitao <leitao@debian.org>
Cc: "David Hildenbrand (Arm)" <david@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Yoshinori Sato <ysato@users.sourceforge.jp>,
Rich Felker <dalias@libc.org>,
John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
Andrii Nakryiko <andrii@kernel.org>,
Martin KaFai Lau <martin.lau@linux.dev>,
Eduard Zingerman <eddyz87@gmail.com>,
Kumar Kartikeya Dwivedi <memxor@gmail.com>,
Song Liu <song@kernel.org>,
Yonghong Song <yonghong.song@linux.dev>,
Jiri Olsa <jolsa@kernel.org>, Lorenzo Stoakes <ljs@kernel.org>,
Vlastimil Babka <vbabka@kernel.org>,
Mike Rapoport <rppt@kernel.org>,
Suren Baghdasaryan <surenb@google.com>,
Michal Hocko <mhocko@suse.com>, Rik van Riel <riel@surriel.com>,
Harry Yoo <harry@kernel.org>, Jann Horn <jannh@google.com>,
"Liam R. Howlett" <liam@infradead.org>,
linux-sh@vger.kernel.org, linux-kernel@vger.kernel.org,
bpf@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH 3/3] mm: remove page_mapped()
Date: Mon, 27 Apr 2026 15:59:16 +0100 [thread overview]
Message-ID: <ae95xHobKZ1MpmVG@casper.infradead.org> (raw)
In-Reply-To: <ae91ogo90bSDFNPC@gmail.com>
On Mon, Apr 27, 2026 at 07:42:46AM -0700, Breno Leitao wrote:
> > > @@ -1353,7 +1353,7 @@ static bool panic_on_unrecoverable_mf(un
> > > cpu_relax();
> > > return page_count(p) == 0 &&
> > > !PageLRU(p) &&
> > > - !page_mapped(p) &&
> > > + !folio_mapped(page_folio(p)) &&
> > > !page_folio(p)->mapping &&
> >
> > If we have a folio, we should really lookup the folio once. Not 4 times.
>
> Why 4 times?
Because there are page_folio() calls hidden in PageLRU, page_mapped()
and page_count().
> > Breno's patch likely needs some love. :)
>
> Would something like the following give it all the love in the world?
>
> folio = page_folio(p);
> return page_count(p) == 0 &&
> !PageLRU(p) &&
> !folio_mapped(folio) &&
> !folio->mapping &&
> !is_free_buddy_page(p);
No. You need to immerse yourself more deeply in the folio transition
;-)
prev parent reply other threads:[~2026-04-27 14:59 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-04-27 11:43 [PATCH 0/3] mm: remove page_mapped() David Hildenbrand (Arm)
2026-04-27 11:43 ` [PATCH 1/3] sh: use folio_mapped() instead of page_mapped() in sh4_flush_cache_page() David Hildenbrand (Arm)
2026-04-27 12:43 ` Matthew Wilcox
2026-04-27 11:43 ` [PATCH 2/3] bpf: arena: use page_ref_count() instead of page_mapped() in arena_free_pages() David Hildenbrand (Arm)
2026-04-27 12:17 ` Andrew Morton
2026-04-27 15:00 ` Alexei Starovoitov
2026-04-27 15:15 ` Andrew Morton
2026-04-27 15:27 ` Alexei Starovoitov
2026-04-27 13:00 ` Matthew Wilcox
2026-04-27 11:43 ` [PATCH 3/3] mm: remove page_mapped() David Hildenbrand (Arm)
2026-04-27 13:12 ` Matthew Wilcox
2026-04-27 13:21 ` Andrew Morton
2026-04-27 13:23 ` David Hildenbrand (Arm)
2026-04-27 14:42 ` Breno Leitao
2026-04-27 14:59 ` Matthew Wilcox [this message]
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