linux-kernel - Re: [PATCH] mm/filemap: Fix logic around SIGBUS in filemap_map

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Message-ID: <aR9JDud3PS-A_hcg@casper.infradead.org>
Date: Thu, 20 Nov 2025 16:59:58 +0000
From: Matthew Wilcox <willy@...radead.org>
To: Kiryl Shutsemau <kirill@...temov.name>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>,
	Hugh Dickins <hughd@...gle.com>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>,
	Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	"Liam R. Howlett" <Liam.Howlett@...cle.com>,
	Vlastimil Babka <vbabka@...e.cz>, Mike Rapoport <rppt@...nel.org>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Michal Hocko <mhocko@...e.com>, Rik van Riel <riel@...riel.com>,
	Harry Yoo <harry.yoo@...cle.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Shakeel Butt <shakeel.butt@...ux.dev>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	"Darrick J. Wong" <djwong@...nel.org>,
	Dave Chinner <david@...morbit.com>, linux-mm@...ck.org,
	linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
	Kiryl Shutsemau <kas@...nel.org>, Chris Mason <clm@...a.com>
Subject: Re: [PATCH] mm/filemap: Fix logic around SIGBUS in
 filemap_map_pages()

On Thu, Nov 20, 2025 at 04:14:11PM +0000, Kiryl Shutsemau wrote:
> Chris noticed that filemap_map_pages() calculates can_map_large only
> once for the first page in the fault around range. The value is not
> valid for the following pages in the range and must be recalculated.
> 
> Instead of recalculating can_map_large on each iteration, pass down
> file_end to filemap_map_folio_range() and let it make the decision on
> what can be mapped.
> 
> Signed-off-by: Kiryl Shutsemau <kas@...nel.org>
> Reported-by: Chris Mason <clm@...a.com>
> Fixes: 74207de2ba10 ("mm/memory: do not populate page table entries beyond i_size")h

Reviewed-by: Matthew Wilcox (Oracle) <willy@...radead.org>