linux-kernel - Re: [PATCH] mm/vmalloc: fix mischeck pfn valid in vmap

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Message-ID: <20250312061836.GA12841@lst.de>
Date: Wed, 12 Mar 2025 07:18:36 +0100
From: Christoph Hellwig <hch@....de>
To: Huan Yang <link@...o.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	Uladzislau Rezki <urezki@...il.com>,
	Ryan Roberts <ryan.roberts@....com>, Zi Yan <ziy@...dia.com>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Mike Rapoport (IBM)" <rppt@...nel.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, opensource.kernel@...o.com,
	Christoph Hellwig <hch@....de>,
	Bingbu Cao <bingbu.cao@...ux.intel.com>
Subject: Re: [PATCH] mm/vmalloc: fix mischeck pfn valid in vmap_pfns

On Wed, Mar 12, 2025 at 02:15:12PM +0800, Huan Yang wrote:
> When invoke vmap_pfns, it call vmap_pfn_apply to set pfn into pte.
> It check pfn is valid, if true then warn and return.
> 
> This is a mischeck, actually we need set a valid pfn into pte, not an
> invalid pfn.

As just discussed this is wrong.  vmap_pfn is for mapping non-page
PFNs and the check is what enforces that.  What is the point of having
that detailed discussion if you just send the broken patch anyway with
a commit log not even acknowledging the facts?