linux-kernel - Re: [PATCH v3] mm/page_alloc: prevent reporting pcp->batch = 0

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Message-ID: <20251216144222.2982594-1-joshua.hahnjy@gmail.com>
Date: Tue, 16 Dec 2025 06:42:21 -0800
From: Joshua Hahn <joshua.hahnjy@...il.com>
To: Matthew Wilcox <willy@...radead.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Daniel Palmer <daniel@...f.com>,
	Brendan Jackman <jackmanb@...gle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Michal Hocko <mhocko@...e.com>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Zi Yan <ziy@...dia.com>,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	kernel-team@...a.com
Subject: Re: [PATCH v3] mm/page_alloc: prevent reporting pcp->batch = 0

On Tue, 16 Dec 2025 14:34:17 +0000 Matthew Wilcox <willy@...radead.org> wrote:

> On Tue, Dec 16, 2025 at 06:27:53AM -0800, Joshua Hahn wrote:
> >  	batch = min(zone_managed_pages(zone) >> 12, SZ_256K / PAGE_SIZE);
> > -	if (batch < 1)
> > +	if (batch <= 1)
> >  		batch = 1;
> >  
> 
> This seems like a no-op to me.  Did you send the right patch?

Hello Matthew,

Thank you for the quick catch, you're totally right. In the original patch [1]
it is also supposed to just return 1 there, but I think I got flustered when
I initially got the bug report and forgot to include that [2]. Sorry for the
mistake, I'll send out a new version with the correct fix.

Thanks again, I hope you have a great day!
Joshua

[1] https://lore.kernel.org/all/20251009192933.3756712-3-joshua.hahnjy@gmail.com/
[2] https://lore.kernel.org/all/20251212015330.1874521-1-joshua.hahnjy@gmail.com/