From: Andrew Morton <akpm@linux-foundation.org>
To: Joonwon Kang <joonwonkang@google.com>
Cc: dennis@kernel.org, tj@kernel.org, cl@gentwo.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
dodam@google.com
Subject: Re: [PATCH v5 4/4] percpu: Fix hint invariant breakage
Date: Tue, 12 May 2026 15:46:28 -0700 [thread overview]
Message-ID: <20260512154628.a30e8eb1827c80e0529b672e@linux-foundation.org> (raw)
In-Reply-To: <20260510072149.1279887-4-joonwonkang@google.com>
On Sun, 10 May 2026 07:21:49 +0000 Joonwon Kang <joonwonkang@google.com> wrote:
> The invariant "scan_hint_start > contig_hint_start if and only if
> scan_hint == contig_hint" should be kept for hint management. However,
> it could be broken in some cases:
>
> - if (new contig == contig_hint == scan_hint) && (contig_hint_start <
> scan_hint_start < new contig start) && the new contig is to become a
> new contig_hint due to its better alignment, then scan_hint should
> be invalidated instead of keeping the old value.
>
> - if (new contig == contig_hint > scan_hint) && (new contig start <
> contig_hint_start) && the new contig is not to become a new
> contig_hint, then scan_hint should be not updated to the new contig.
>
> This commit mainly fixes this invariant breakage and includes more:
Thanks. AI review asked a single question:
https://sashiko.dev/#/patchset/20260510072149.1279887-1-joonwonkang@google.com
next prev parent reply other threads:[~2026-05-12 22:46 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-05-10 7:21 [PATCH v5 1/4] percpu: Fix wrong chunk hints update Joonwon Kang
2026-05-10 7:21 ` [PATCH v5 2/4] percpu: Do not trust hint starts when they are not set Joonwon Kang
2026-05-10 7:21 ` [PATCH v5 3/4] percpu: Introduce struct pcpu_region Joonwon Kang
2026-05-10 7:21 ` [PATCH v5 4/4] percpu: Fix hint invariant breakage Joonwon Kang
2026-05-12 22:46 ` Andrew Morton [this message]
2026-05-13 6:18 ` Joonwon Kang
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