linux-kernel - Re: [PATCH v8 01/10] fs: Allow fine-grained control of folio sizes

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: <Zoc2rCPC5thSIuoR@casper.infradead.org>
Date: Fri, 5 Jul 2024 00:56:28 +0100
From: Matthew Wilcox <willy@...radead.org>
To: Dave Chinner <david@...morbit.com>
Cc: Ryan Roberts <ryan.roberts@....com>,
	"Pankaj Raghav (Samsung)" <kernel@...kajraghav.com>,
	chandan.babu@...cle.com, djwong@...nel.org, brauner@...nel.org,
	akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
	yang@...amperecomputing.com, linux-mm@...ck.org,
	john.g.garry@...cle.com, linux-fsdevel@...r.kernel.org,
	hare@...e.de, p.raghav@...sung.com, mcgrof@...nel.org,
	gost.dev@...sung.com, cl@...amperecomputing.com,
	linux-xfs@...r.kernel.org, hch@....de, Zi Yan <zi.yan@...t.com>
Subject: Re: [PATCH v8 01/10] fs: Allow fine-grained control of folio sizes

On Fri, Jul 05, 2024 at 08:06:51AM +1000, Dave Chinner wrote:
> > > It seems strange to silently clamp these? Presumably for the bs>ps usecase,
> > > whatever values are passed in are a hard requirement? So wouldn't want them to
> > > be silently reduced. (Especially given the recent change to reduce the size of
> > > MAX_PAGECACHE_ORDER to less then PMD size in some cases).
> > 
> > Hm, yes.  We should probably make this return an errno.  Including
> > returning an errno for !IS_ENABLED() and min > 0.
> 
> What are callers supposed to do with an error? In the case of
> setting up a newly allocated inode in XFS, the error would be
> returned in the middle of a transaction and so this failure would
> result in a filesystem shutdown.

I suggest you handle it better than this.  If the device is asking for a
blocksize > PMD_SIZE, you should fail to mount it.  If the device is
asking for a blocksize > PAGE_SIZE and CONFIG_TRANSPARENT_HUGEPAGE is
not set, you should also decline to mount the filesystem.