linux-kernel - Re: [PATCH 0/3] mm: treewide: make get_free

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Message-ID: <aPQxN7-FeFB6vTuv@casper.infradead.org>
Date: Sun, 19 Oct 2025 01:30:47 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Brendan Jackman <jackmanb@...gle.com>,
	David Hildenbrand <david@...hat.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Jiri Slaby <jirislaby@...nel.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Julia Lawall <Julia.Lawall@...ia.fr>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	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
Subject: Re: [PATCH 0/3] mm: treewide: make get_free_pages() and return void *

On Sat, Oct 18, 2025 at 12:29:59PM +0300, Mike Rapoport wrote:
> Vast majority of allocations that use get_free_pages() and its derivatives
> cast the returned unsigned long to a pointer and then cast it back to
> unsigned long when freeing the memory.
> 
> These castings are useless and only obfuscate the code.
> 
> Make get_free_pages() and friends return 'void *' and free_pages() accept
> 'void *' as its address parameter.

No.  Linus has rejected this change before.  I can't find it now, it was
a long time ago.  Most of them shouldn't be using get_free_pages() at
all, they should be using kmalloc().