From: Andrew Morton <akpm@linux-foundation.org>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Josef Bacik <josef@toxicpanda.com>,
David Sterba <dsterba@suse.com>,
Andreas Gruenbacher <agruenba@redhat.com>,
Al Viro <viro@zeniv.linux.org.uk>, Will Deacon <will@kernel.org>,
linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-btrfs@vger.kernel.org
Subject: Re: [PATCH 0/3] Avoid live-lock in fault-in+uaccess loops with sub-page faults
Date: Wed, 24 Nov 2021 13:36:00 -0800 [thread overview]
Message-ID: <20211124133600.94f0b9a6c611ee663c9a8d6d@linux-foundation.org> (raw)
In-Reply-To: <20211124192024.2408218-1-catalin.marinas@arm.com>
On Wed, 24 Nov 2021 19:20:21 +0000 Catalin Marinas <catalin.marinas@arm.com> wrote:
> Hi,
>
> There are a few places in the filesystem layer where a uaccess is
> performed in a loop with page faults disabled, together with a
> fault_in_*() call to pre-fault the pages. On architectures like arm64
> with MTE (memory tagging extensions) or SPARC ADI, even if the
> fault_in_*() succeeded, the uaccess can still fault indefinitely.
>
> In general this is not an issue since such code restarts the
> fault_in_*() from where the uaccess failed, therefore guaranteeing
> forward progress. The btrfs search_ioctl(), however, rewinds the
> fault_in_*() position and it can live-lock. This was reported by Al
> here:
Btrfs livelock on some-of-arm sounds fairly serious. Should we
backport this? If so, a48b73eca4ce ("btrfs: fix potential deadlock in
the search ioctl") appears to be a suitable Fixes: target?
next prev parent reply other threads:[~2021-11-24 21:36 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-24 19:20 [PATCH 0/3] Avoid live-lock in fault-in+uaccess loops with sub-page faults Catalin Marinas
2021-11-24 19:20 ` [PATCH 1/3] mm: Introduce fault_in_exact_writeable() to probe for " Catalin Marinas
2021-11-24 19:20 ` [PATCH 2/3] arm64: Add support for sub-page faults user probing Catalin Marinas
2021-11-24 19:20 ` [PATCH 3/3] btrfs: Avoid live-lock in search_ioctl() on hardware with sub-page faults Catalin Marinas
2021-11-24 20:03 ` Matthew Wilcox
2021-11-24 20:37 ` Catalin Marinas
2021-11-25 22:25 ` Andreas Gruenbacher
2021-11-25 22:42 ` Catalin Marinas
2021-11-26 22:29 ` Andreas Gruenbacher
2021-11-26 22:57 ` Catalin Marinas
2021-11-27 3:52 ` Andreas Gruenbacher
2021-11-27 14:33 ` Catalin Marinas
2021-11-27 12:39 ` Andreas Gruenbacher
2021-11-27 15:21 ` Catalin Marinas
2021-11-27 18:05 ` Andreas Gruenbacher
2021-11-29 12:16 ` Catalin Marinas
2021-11-29 13:33 ` Andreas Gruenbacher
2021-11-29 15:36 ` Catalin Marinas
2021-11-29 18:40 ` Linus Torvalds
2021-11-29 19:31 ` Andreas Gruenbacher
2021-11-29 20:56 ` Catalin Marinas
2021-11-29 21:53 ` Linus Torvalds
2021-11-29 23:12 ` Catalin Marinas
2021-11-29 13:52 ` Catalin Marinas
2021-11-24 23:00 ` Linus Torvalds
2021-11-25 11:10 ` Catalin Marinas
2021-11-25 18:13 ` Linus Torvalds
2021-11-25 20:43 ` Catalin Marinas
2021-11-25 21:02 ` Matthew Wilcox
2021-11-25 21:29 ` Catalin Marinas
2021-11-25 21:40 ` Andreas Gruenbacher
2021-11-26 16:42 ` David Sterba
2021-11-24 21:36 ` Andrew Morton [this message]
2021-11-24 22:31 ` [PATCH 0/3] Avoid live-lock in fault-in+uaccess loops " Catalin Marinas
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20211124133600.94f0b9a6c611ee663c9a8d6d@linux-foundation.org \
--to=akpm@linux-foundation.org \
--cc=agruenba@redhat.com \
--cc=catalin.marinas@arm.com \
--cc=dsterba@suse.com \
--cc=josef@toxicpanda.com \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-btrfs@vger.kernel.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=torvalds@linux-foundation.org \
--cc=viro@zeniv.linux.org.uk \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).