linux-kernel - Re: [PATCH] mm: Make kvmalloc refuse to allocate more than 2GB

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Message-ID: <YPmEIAQWUD4i/aPR@mit.edu>
Date:   Thu, 22 Jul 2021 10:43:44 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     "Matthew Wilcox (Oracle)" <willy@...radead.org>
Cc:     Al Viro <viro@...iv.linux.org.uk>,
        Qualys Security Advisory <qsa@...lys.com>,
        Eric Sandeen <sandeen@...hat.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mm: Make kvmalloc refuse to allocate more than 2GB

On Wed, Jul 21, 2021 at 07:41:31PM +0100, Matthew Wilcox (Oracle) wrote:
> It's generally dangerous to allocate such large quantities of memory
> within the kernel owing to our propensity to use 'int' to represent
> a length.  If somebody really needs it, we can add a kvmalloc_large()
> later, but let's default to "You can't allocate that much memory".

If we really need it, maybe we can add a GFP_LARGE_ALLOC to allow
allocations larger than 2GB later on?  I can't quite see why that
would ever be needed, but that's probably a failure of my imagination.  :-)

      	      	      	  	 - Ted