From: Marco Elver <elver@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>,
Alexander Potapenko <glider@google.com>,
Dmitry Vyukov <dvyukov@google.com>,
Vlastimil Babka <vbabka@suse.cz>,
Oscar Salvador <osalvador@suse.de>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
kasan-dev@googlegroups.com,
Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Subject: Re: [PATCH] stackdepot: fix stack_depot_save_flags() in NMI context
Date: Thu, 28 Nov 2024 10:13:59 +0100 [thread overview]
Message-ID: <CANpmjNPDVORFLCqnm3n1RHnJBKdim_x=kurbOJ0QYxaztT4q=g@mail.gmail.com> (raw)
In-Reply-To: <20241127172523.b12b82d150aad5069e024645@linux-foundation.org>
On Thu, 28 Nov 2024 at 02:25, Andrew Morton <akpm@linux-foundation.org> wrote:
>
> On Fri, 22 Nov 2024 16:39:47 +0100 Marco Elver <elver@google.com> wrote:
>
> > Per documentation, stack_depot_save_flags() was meant to be usable from
> > NMI context if STACK_DEPOT_FLAG_CAN_ALLOC is unset. However, it still
> > would try to take the pool_lock in an attempt to save a stack trace in
> > the current pool (if space is available).
> >
> > This could result in deadlock if an NMI is handled while pool_lock is
> > already held. To avoid deadlock, only try to take the lock in NMI
> > context and give up if unsuccessful.
>
> Is it possible to trigger this deadlock in current kernels, or is this
> a might-happen-in-the-future thing?
I can't find evidence this happens right now (at least with the quick
test I just ran), so it's more of a might happen if use of this API
broadens.
Thanks,
-- Marco
prev parent reply other threads:[~2024-11-28 9:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-11-22 15:39 Marco Elver
2024-11-22 17:38 ` Sebastian Andrzej Siewior
2024-11-28 1:25 ` Andrew Morton
2024-11-28 9:13 ` Marco Elver [this message]
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='CANpmjNPDVORFLCqnm3n1RHnJBKdim_x=kurbOJ0QYxaztT4q=g@mail.gmail.com' \
--to=elver@google.com \
--cc=akpm@linux-foundation.org \
--cc=andreyknvl@gmail.com \
--cc=bigeasy@linutronix.de \
--cc=dvyukov@google.com \
--cc=glider@google.com \
--cc=kasan-dev@googlegroups.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=osalvador@suse.de \
--cc=vbabka@suse.cz \
/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