linux-kernel - Re: [PATCH 1/2] mm/khugepaged: do synchronous writeback for MADV

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <aRH2pdhMBQ-20IC9@casper.infradead.org>
Date: Mon, 10 Nov 2025 14:28:53 +0000
From: Matthew Wilcox <willy@...radead.org>
To: "Garg, Shivank" <shivankg@....com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	David Hildenbrand <david@...hat.com>, Zi Yan <ziy@...dia.com>,
	Baolin Wang <baolin.wang@...ux.alibaba.com>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>,
	Nico Pache <npache@...hat.com>, Ryan Roberts <ryan.roberts@....com>,
	Dev Jain <dev.jain@....com>, Barry Song <baohua@...nel.org>,
	Lance Yang <lance.yang@...ux.dev>,
	Steven Rostedt <rostedt@...dmis.org>,
	Masami Hiramatsu <mhiramat@...nel.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Zach O'Keefe <zokeefe@...gle.com>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, linux-trace-kernel@...r.kernel.org,
	Branden Moore <Branden.Moore@....com>
Subject: Re: [PATCH 1/2] mm/khugepaged: do synchronous writeback for
 MADV_COLLAPSE

On Mon, Nov 10, 2025 at 07:50:17PM +0530, Garg, Shivank wrote:
> The issue is copying those binary to a freshly mounted filesystem.
> The page cache folios remain dirty until background writeback completes.
> 
> Reproduces 100% for me: fresh XFS/EXT4 mount -> copy binary -> execute -> MADV_COLLAPSE fails.

Yes, but this is an uncommon thing to do.  Really, it's the kind of
thing you do when you're testing something (like, whether ext4 supports
large folios, and whether that yields a performance improvement).
It's more reasonable to change userspace than the kernel to solve this
problem you're having.