linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Christian Brauner <christian.brauner@ubuntu.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Arve Hjonnevag <arve@android.com>, Todd Kjos <tkjos@android.com>,
	Martijn Coenen <maco@android.com>,
	Joel Fernandes <joel@joelfernandes.org>,
	Christian Brauner <christian@brauner.io>,
	syzbot <syzbot+e5344baa319c9a96edec@syzkaller.appspotmail.com>,
	acme@kernel.org, alexander.shishkin@linux.intel.com,
	jolsa@redhat.com, linux-kernel@vger.kernel.org,
	mark.rutland@arm.com, mingo@redhat.com, namhyung@kernel.org,
	peterz@infradead.org, syzkaller-bugs@googlegroups.com,
	"open list:ANDROID DRIVERS" <devel@driverdev.osuosl.org>,
	linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH v2] binder: Don't use mmput() from shrinker function.
Date: Thu, 16 Jul 2020 18:29:31 +0200	[thread overview]
Message-ID: <20200716162931.g3delsp7qmfjup6x@wittgenstein> (raw)
In-Reply-To: <20200716151756.GO31089@dhcp22.suse.cz>

On Thu, Jul 16, 2020 at 05:17:56PM +0200, Michal Hocko wrote:
> On Fri 17-07-20 00:12:15, Tetsuo Handa wrote:
> > syzbot is reporting that mmput() from shrinker function has a risk of
> > deadlock [1], for delayed_uprobe_add() from update_ref_ctr() calls
> > kzalloc(GFP_KERNEL) with delayed_uprobe_lock held, and
> > uprobe_clear_state() from __mmput() also holds delayed_uprobe_lock.
> > 
> > Commit a1b2289cef92ef0e ("android: binder: drop lru lock in isolate
> > callback") replaced mmput() with mmput_async() in order to avoid sleeping
> > with spinlock held. But this patch replaces mmput() with mmput_async() in
> > order not to start __mmput() from shrinker context.
> > 
> > [1] https://syzkaller.appspot.com/bug?id=bc9e7303f537c41b2b0cc2dfcea3fc42964c2d45
> > 
> > Reported-by: syzbot <syzbot+1068f09c44d151250c33@syzkaller.appspotmail.com>
> > Reported-by: syzbot <syzbot+e5344baa319c9a96edec@syzkaller.appspotmail.com>
> > Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
> 
> Reviewed-by: Michal Hocko <mhocko@suse.com>

Thanks for the careful review Michal!
Does this need a Cc: stable?

Otherwise

Acked-by: Christian Brauner <christian.brauner@ubuntu.com>

Thanks!
Christian

  reply	other threads:[~2020-07-16 16:29 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-15 19:59 possible deadlock in uprobe_clear_state (2) syzbot
2020-07-15 23:36 ` [PATCH] binder: Don't use mmput() from shrinker function Tetsuo Handa
2020-07-16  8:35   ` Michal Hocko
2020-07-16 13:41     ` Tetsuo Handa
2020-07-16 13:54       ` Michal Hocko
2020-07-16 15:12         ` [PATCH v2] " Tetsuo Handa
2020-07-16 15:17           ` Michal Hocko
2020-07-16 16:29             ` Christian Brauner [this message]
2020-07-16 22:27               ` Tetsuo Handa
2020-07-16 23:53             ` Todd Kjos

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=20200716162931.g3delsp7qmfjup6x@wittgenstein \
    --to=christian.brauner@ubuntu.com \
    --cc=acme@kernel.org \
    --cc=alexander.shishkin@linux.intel.com \
    --cc=arve@android.com \
    --cc=christian@brauner.io \
    --cc=devel@driverdev.osuosl.org \
    --cc=gregkh@linuxfoundation.org \
    --cc=joel@joelfernandes.org \
    --cc=jolsa@redhat.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-mm@kvack.org \
    --cc=maco@android.com \
    --cc=mark.rutland@arm.com \
    --cc=mhocko@kernel.org \
    --cc=mingo@redhat.com \
    --cc=namhyung@kernel.org \
    --cc=penguin-kernel@i-love.sakura.ne.jp \
    --cc=peterz@infradead.org \
    --cc=syzbot+e5344baa319c9a96edec@syzkaller.appspotmail.com \
    --cc=syzkaller-bugs@googlegroups.com \
    --cc=tkjos@android.com \
    /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).