linux-kernel - Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages

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Message-ID: <h3njg4vlzeq3nkeoxx47zlq56hzyueq2g5kaoititfrmjizqe3@4yvoyckuszxk>
Date: Thu, 11 Sep 2025 15:58:41 -0700
From: Shakeel Butt <shakeel.butt@...ux.dev>
To: Suren Baghdasaryan <surenb@...gle.com>
Cc: akpm@...ux-foundation.org, kent.overstreet@...ux.dev, vbabka@...e.cz, 
	mhocko@...e.com, jackmanb@...gle.com, hannes@...xchg.org, ziy@...dia.com, 
	usamaarif642@...il.com, 00107082@....com, pasha.tatashin@...een.com, 
	souravpanda@...gle.com, linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound
 "tail" pages

On Tue, Sep 09, 2025 at 04:34:09PM -0700, Suren Baghdasaryan wrote:
> When freeing "tail" pages of a non-compount high-order page, we properly
> subtract the allocation tag counters, however later when these pages are
> released, alloc_tag_sub() will issue warnings because tags for these pages
> are NULL.
> This issue was originally anticipated by Vlastimil in his review [1] and
> then recently reported by David.
> Prevent warnings by marking the tags empty.
> 
> [1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/
> 
> Suggested-by: David Wang <00107082@....com>
> Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>

Acked-by: Shakeel Butt <shakeel.butt@...ux.dev>