From: Kiryl Shutsemau <kirill@shutemov.name>
To: David Hildenbrand <david@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Matthew Wilcox <willy@infradead.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Alexander Viro <viro@zeniv.linux.org.uk>,
Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm/filemap: Implement fast short reads
Date: Thu, 23 Oct 2025 11:31:32 +0100 [thread overview]
Message-ID: <hb54gc3iezwzpe2j6ssgqtwcnba4pnnffzlh3eb46preujhnoa@272dqbjakaiy> (raw)
In-Reply-To: <dcdfb58c-5ba7-4015-9446-09d98449f022@redhat.com>
On Wed, Oct 22, 2025 at 07:28:27PM +0200, David Hildenbrand wrote:
> "garbage" as in pointing at something without a direct map, something that's
> protected differently (MTE? weird CoCo protection?) or even worse MMIO with
> undesired read-effects.
Pedro already points to the problem with missing direct mapping.
_nofault() copy should help with this.
Can direct mapping ever be converted to MMIO? It can be converted to DMA
buffer (which is fine), but MMIO? I have not seen it even in virtualized
environments.
I cannot say for all CoCo protections, but TDX guest shared<->private
should be fine.
I am not sure about MTE. Is there a way to bypass MTE check for a load?
And how does it deal with stray reads from load_unaligned_zeropad()?
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2025-10-23 10:31 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-17 14:15 Kiryl Shutsemau
2025-10-18 2:38 ` kernel test robot
2025-10-18 3:54 ` kernel test robot
2025-10-18 4:46 ` kernel test robot
2025-10-18 17:56 ` Linus Torvalds
2025-10-20 11:03 ` Kiryl Shutsemau
2025-10-20 4:53 ` Andrew Morton
2025-10-20 11:33 ` Kiryl Shutsemau
2025-10-21 15:50 ` Linus Torvalds
2025-10-21 23:39 ` Dave Chinner
2025-10-22 4:25 ` Linus Torvalds
2025-10-22 8:00 ` Dave Chinner
2025-10-22 15:31 ` Linus Torvalds
2025-10-23 7:50 ` Dave Chinner
2025-10-23 9:37 ` Jan Kara
2025-10-21 15:47 ` Linus Torvalds
2025-10-22 7:08 ` Pedro Falcato
2025-10-22 7:13 ` Linus Torvalds
2025-10-22 7:38 ` Pedro Falcato
2025-10-22 10:00 ` Kiryl Shutsemau
2025-10-22 17:28 ` David Hildenbrand
2025-10-23 10:31 ` Kiryl Shutsemau [this message]
2025-10-23 10:54 ` David Hildenbrand
2025-10-23 11:09 ` Kiryl Shutsemau
2025-10-23 12:08 ` David Hildenbrand
2025-10-23 11:10 ` David Hildenbrand
2025-10-23 11:11 ` David Hildenbrand
2025-10-23 11:40 ` Kiryl Shutsemau
2025-10-23 11:49 ` David Hildenbrand
2025-10-23 12:41 ` Kiryl Shutsemau
2025-10-23 17:42 ` Yang Shi
2025-10-27 10:49 ` Hugh Dickins
2025-10-27 15:50 ` Linus Torvalds
2025-10-27 16:06 ` David Hildenbrand
2025-10-27 16:48 ` Linus Torvalds
2025-10-27 16:53 ` David Hildenbrand
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