linux-kernel - Re: [RFC, PATCH 0/2] Large folios vs. SIGBUS semantics

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Message-ID: <cas6g5sw6bffqo5e634tmyivdamcagoynztic7s53634mv2kwk@6a552oryikew>
Date: Tue, 21 Oct 2025 07:17:11 +0100
From: Kiryl Shutsemau <kirill@...temov.name>
To: Christoph Hellwig <hch@...radead.org>
Cc: Dave Chinner <david@...morbit.com>, 
	Andrew Morton <akpm@...ux-foundation.org>, David Hildenbrand <david@...hat.com>, 
	Hugh Dickins <hughd@...gle.com>, Matthew Wilcox <willy@...radead.org>, 
	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>, linux-mm@...ck.org, linux-fsdevel@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [RFC, PATCH 0/2] Large folios vs. SIGBUS semantics

On Mon, Oct 20, 2025 at 11:12:40PM -0700, Christoph Hellwig wrote:
> On Tue, Oct 21, 2025 at 10:28:02AM +1100, Dave Chinner wrote:
> > Fundamentally, we really don't care about the mapping/tlb
> > performance of the PTE fragments at EOF. Anyone using files large
> > enough to notice the TLB overhead improvements from mapping large
> > folios is not going to notice that the EOF mapping has a slightly
> > higher TLB miss overhead than everywhere else in the file.
> > 
> > Please jsut fix the regression.
> 
> Yeah.  I'm not even sure why we're having this discussion.  The
> behavior is mandated, we have test cases for it and there is
> literally no practical upside in changing the behavior from what
> we've done forever and what is mandated in Posix.

Okay, will fix.

-- 
  Kiryl Shutsemau / Kirill A. Shutemov