From: Johannes Weiner <hannes@cmpxchg.org>
To: Brendan Jackman <jackmanb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@kernel.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Yosry Ahmed <yosry.ahmed@linux.dev>
Subject: Re: [PATCH] mm/page_alloc: Clarify some migratetype fallback code
Date: Fri, 21 Feb 2025 12:33:03 -0500 [thread overview]
Message-ID: <20250221173303.GA1316314@cmpxchg.org> (raw)
In-Reply-To: <CA+i-1C1m-p0GkYE8QTd39qEG3Pb_QMsEs=dLH1_87giDVhVH2A@mail.gmail.com>
On Fri, Feb 21, 2025 at 06:24:45PM +0100, Brendan Jackman wrote:
> On Tue, 18 Feb 2025 at 21:38, Johannes Weiner <hannes@cmpxchg.org> wrote:
> >
> > @@ -1930,7 +1929,7 @@ steal_suitable_fallback(struct zone *zone, struct page *page,
> /*
> * This can happen due to races and we want to prevent broken
> * highatomic accounting.
> */
> > if (is_migrate_highatomic(block_type))
> > - goto single_page;
> > + return NULL;
>
> Side question: when does this happen? Might have a spooky gap in my
> understanding here as I thought the only reason the pageblock typed
> was changed without the zone lock held was during memory hotplug.
Good job catching that. I don't think they are needed anymore after
the hygiene patches. I had proposed removing them as a follow-up, but
never got around to it:
https://lore.kernel.org/linux-mm/20230912150320.GB3228@cmpxchg.org/
I'll send a proper patch.
next prev parent reply other threads:[~2025-02-21 17:33 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-14 18:14 [PATCH] mm/page_alloc: Clarify some migratetype fallback code Brendan Jackman
2025-02-14 21:26 ` Johannes Weiner
2025-02-17 16:26 ` Brendan Jackman
2025-02-18 10:19 ` Vlastimil Babka
2025-02-18 20:38 ` Johannes Weiner
2025-02-19 11:01 ` Vlastimil Babka
2025-02-21 17:24 ` Brendan Jackman
2025-02-21 17:33 ` Johannes Weiner [this message]
2025-02-24 12:35 ` Brendan Jackman
2025-02-25 8:40 ` Vlastimil Babka
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