From: Oleg Nesterov <oleg@redhat.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: syzbot <syzbot+b70f2aabc707c69c9239@syzkaller.appspotmail.com>,
chanho.min@lge.com, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, pavel@ucw.cz,
rafael.j.wysocki@intel.com, syzkaller-bugs@googlegroups.com,
viro@zeniv.linux.org.uk
Subject: Re: WARNING: syz-executor still has locks held!
Date: Wed, 20 Mar 2019 16:00:54 +0100 [thread overview]
Message-ID: <20190320150053.GD21673@redhat.com> (raw)
In-Reply-To: <20190320132936.GB8696@dhcp22.suse.cz>
On 03/20, Michal Hocko wrote:
>
> On Wed 20-03-19 14:24:11, Oleg Nesterov wrote:
> > On 03/20, Michal Hocko wrote:
> > >
> > > Yes we do hold the cgred mutex while calling freezable_schedule but why
> > > are we getting a warning is not really clear to me. The task should be
> > > hidden from the freezer so why do we warn at all?
> >
> > try_to_freeze() calls debug_check_no_locks_held() and this makes sense.
>
> Yes it does. But it already ignores PF_NOFREEZE tasks and I fail to see
> why is PF_FREEZER_SKIP any different.
But they differ. PF_NOFREEZE is a "sticky" flag for kthreads. Set by default,
cleared by set_freezable() if you want a freezable kthread.
PF_FREEZER_SKIP means that a sleeping freezable task will call try_to_freeze()
right after schedule() returns, so try_to_freeze_tasks() can safely count it as
"already frozen".
> it seems that skipping the task was the only viable option
> to fix suspend issues
Yes, de_thread() should use freezable_schedule(), iow I hope we will reconsider
this (reverted) patch.
> as removing the cgred is way way too complicated.
We need to do this anyway, this leads to other more serious problems...
Oleg.
next prev parent reply other threads:[~2019-03-20 15:01 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-24 17:40 WARNING: syz-executor still has locks held! syzbot
2019-03-20 12:24 ` syzbot
2019-03-20 13:16 ` Michal Hocko
2019-03-20 13:24 ` Oleg Nesterov
2019-03-20 13:29 ` Michal Hocko
2019-03-20 15:00 ` Oleg Nesterov [this message]
2019-03-20 15:12 ` Michal Hocko
2019-03-20 17:30 ` Oleg Nesterov
2019-03-20 19:45 ` Michal Hocko
2019-03-20 20:32 ` Michal Hocko
2019-03-21 17:28 ` Oleg Nesterov
2019-03-22 10:36 ` Michal Hocko
2019-03-22 10:35 ` Pavel Machek
2019-03-20 13:18 ` Oleg Nesterov
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=20190320150053.GD21673@redhat.com \
--to=oleg@redhat.com \
--cc=chanho.min@lge.com \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mhocko@kernel.org \
--cc=pavel@ucw.cz \
--cc=rafael.j.wysocki@intel.com \
--cc=syzbot+b70f2aabc707c69c9239@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=viro@zeniv.linux.org.uk \
/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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.