netdev.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: "Rafael J. Wysocki" <rjw-KKrjLPT3xs0@public.gmane.org>
To: Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
Cc: Linus Torvalds
	<torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Michael Leun
	<lkml20130126-yS7QfQBdiAdyjo5WHAzKoQ@public.gmane.org>,
	lkml <linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Pavel Machek <pavel-+ZI9xUNit7I@public.gmane.org>,
	Peter Zijlstra <peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Ingo Molnar <mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Andrew Morton
	<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>,
	Mandeep Singh Baines
	<msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org>,
	Oleg Nesterov <oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	linux-nfs <linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Linux PM list <linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	netdev <netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org>,
	Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>,
	Darren Hart <dvhart-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>,
	Thomas Gleixner <tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org>,
	Randy Dunlap <rdunlap-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>,
	Al Viro <viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org>
Subject: Re: 3.11-rc regression bisected: s2disk does not work (was Re: [PATCH v3 13/16] futex: use freezable blocking call)
Date: Tue, 23 Jul 2013 03:41:42 +0200	[thread overview]
Message-ID: <15305281.aClQ8XUG9t@vostro.rjw.lan> (raw)
In-Reply-To: <CAMbhsRReF9xB597i9CcCj7D1P5kvB4cc0JmDQYeboqi11Kp99A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>

On Monday, July 22, 2013 05:42:49 PM Colin Cross wrote:
> On Mon, Jul 22, 2013 at 5:32 PM, Linus Torvalds
> <torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org> wrote:
> > On Mon, Jul 22, 2013 at 4:55 PM, Colin Cross <ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org> wrote:
> >>
> >> I think the right solution is to add a flag to the freezing task that
> >> marks it unfreezable.  I  think PF_NOFREEZE would work, although it is
> >> normally used on kernel threads, can you see if the attached patch
> >> helps?
> >
> > Hmm. That does seem to be the right thing to do, but I wonder about
> > the *other* callers of freeze_processes() IOW, kexec and friends.
> >
> > So maybe we should do this in {freeze|thaw}_processes() itself, and
> > just make the rule be that the caller of freeze_processes() itself is
> > obviously not frozen, and has to be the same one that then thaws
> > things?
> >
> > Colin? Rafael? Comments?
> >
> >                 Linus
> 
> I was worried about clearing the flag in thaw_processes().  If a
> kernel thread with PF_NOFREEZE set ever called thaw_processes(), which
> autosleep might do, it would clear the flag.  Or if a different thread
> called freeze_processes() and thaw_processes().

Is that legitimate?

> All the other callers besides the SNAPSHOT_FREEZE ioctl stay in the kernel
> between freeze_processes() and thaw_processes(), which makes the fanout of
> places that could call try_to_freeze() much more controllable.
> 
> Using a new flag that operates like PF_NOFREEZE but doesn't conflict
> with it, or a nofreeze_depth counter, would also work.

Well, that would be robust enough.  At least if the purpose of that new flag
is clearly specified, people hopefully won't be tempted to optimize it away in
the future.

Thanks,
Rafael


-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
--
To unsubscribe from this list: send the line "unsubscribe linux-nfs" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

  parent reply	other threads:[~2013-07-23  1:41 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-05-06 23:50 [PATCH v2 00/10] optimize freezing tasks by reducing task wakeups Colin Cross
2013-05-06 23:50 ` [PATCH v3 01/16] freezer: add unsafe versions of freezable helpers for NFS Colin Cross
2013-05-06 23:50 ` [PATCH v3 02/16] freezer: add unsafe versions of freezable helpers for CIFS Colin Cross
2013-05-07 10:07   ` Jeff Layton
     [not found]     ` <20130507060730.03364687-9yPaYZwiELC+kQycOl6kW4xkIHaj4LzF@public.gmane.org>
2013-05-07 17:47       ` Colin Cross
     [not found]         ` <CAMbhsRQ1i_dFctwjkqjg3=GJdEc8ReEDk=NnEFEXj8u3MaEqDA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-05-07 17:52           ` [PATCH v4 " Colin Cross
     [not found]             ` <1367949125-21809-1-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
2013-05-07 18:11               ` Jeff Layton
     [not found]   ` <1367884221-20462-3-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
2013-05-07 12:28     ` [PATCH v3 " Pavel Machek
2013-05-06 23:50 ` [PATCH v3 03/16] lockdep: remove task argument from debug_check_no_locks_held Colin Cross
2013-05-07 12:28   ` Pavel Machek
2013-05-06 23:50 ` [PATCH v3 04/16] lockdep: check that no locks held at freeze time Colin Cross
     [not found]   ` <1367884221-20462-5-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
2013-05-07 12:29     ` Pavel Machek
     [not found] ` <1367884221-20462-1-git-send-email-ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org>
2013-05-06 23:50   ` [PATCH v3 05/16] freezer: shorten freezer sleep time using exponential backoff Colin Cross
2013-05-06 23:50   ` [PATCH v3 06/16] freezer: skip waking up tasks with PF_FREEZER_SKIP set Colin Cross
2013-05-06 23:50 ` [PATCH v3 07/16] freezer: convert freezable helpers to freezer_do_not_count() Colin Cross
2013-05-06 23:50 ` [PATCH v3 08/16] freezer: convert freezable helpers to static inline where possible Colin Cross
2013-05-06 23:50 ` [PATCH v3 09/16] freezer: add new freezable helpers using freezer_do_not_count() Colin Cross
2013-05-06 23:50 ` [PATCH v3 10/16] binder: use freezable blocking calls Colin Cross
2013-05-06 23:50 ` [PATCH v3 11/16] epoll: use freezable blocking call Colin Cross
2013-05-06 23:50 ` [PATCH v3 12/16] select: " Colin Cross
2013-05-06 23:50 ` [PATCH v3 13/16] futex: " Colin Cross
2013-07-22 23:02   ` 3.11-rc regression bisected: s2disk does not work (was Re: [PATCH v3 13/16] futex: use freezable blocking call) Michael Leun
2013-07-22 23:55     ` Colin Cross
2013-07-23  0:32       ` Linus Torvalds
     [not found]         ` <CA+55aFzUVPJe96z8V0F-znc8ZcpJid7LEeYww80M-Mx=S91tAA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-23  0:42           ` Colin Cross
     [not found]             ` <CAMbhsRReF9xB597i9CcCj7D1P5kvB4cc0JmDQYeboqi11Kp99A-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-23  1:41               ` Rafael J. Wysocki [this message]
     [not found]                 ` <15305281.aClQ8XUG9t-sKB8Sp2ER+y1GS7QM15AGw@public.gmane.org>
2013-07-23  6:28                   ` Colin Cross
2013-07-23 20:31                     ` Colin Cross
2013-07-23 21:58                       ` Michael Leun
2013-07-23 18:08       ` Michael Leun
2013-07-23 18:24         ` Darren Hart
2013-07-23 18:29         ` Colin Cross
2013-07-23 19:16           ` Michael Leun
     [not found]             ` <20130723211622.50f75087-gjVD6BTPoEbYa4IuQwzu8g@public.gmane.org>
2013-07-23 19:29               ` Colin Cross
     [not found]                 ` <CAMbhsRQU=TswYg-2WqHmzt-_GpfMFpYHPSU4eFd5XMw7DRGXJA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-23 19:58                   ` Michael Leun
     [not found]           ` <CAMbhsRT6zOKLhG_uh=nA8H_3d7afhG+4jvWjvidY3fEguryP_Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2013-07-23 21:43             ` Rafael J. Wysocki
     [not found]     ` <20130723010250.5a3465ec-gjVD6BTPoEbYa4IuQwzu8g@public.gmane.org>
2013-07-23  0:26       ` Pavel Machek
2013-05-06 23:50 ` [PATCH v3 14/16] nanosleep: use freezable blocking call Colin Cross
2013-05-06 23:50 ` [PATCH v3 15/16] sigtimedwait: " Colin Cross
2013-05-06 23:50 ` [PATCH v3 16/16] af_unix: use freezable blocking calls in read Colin Cross
2013-05-07 18:12 ` [PATCH v2 00/10] optimize freezing tasks by reducing task wakeups Tejun Heo
2013-05-08  0:02   ` Rafael J. Wysocki

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=15305281.aClQ8XUG9t@vostro.rjw.lan \
    --to=rjw-kkrjlpt3xs0@public.gmane.org \
    --cc=akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
    --cc=ccross-z5hGa2qSFaRBDgjK7y7TUQ@public.gmane.org \
    --cc=dvhart-VuQAYsv1563Yd54FQh9/CA@public.gmane.org \
    --cc=linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-nfs-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=linux-pm-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=lkml20130126-yS7QfQBdiAdyjo5WHAzKoQ@public.gmane.org \
    --cc=mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
    --cc=msb-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org \
    --cc=netdev-u79uwXL29TY76Z2rM5mHXA@public.gmane.org \
    --cc=oleg-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org \
    --cc=pavel-+ZI9xUNit7I@public.gmane.org \
    --cc=peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org \
    --cc=rdunlap-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org \
    --cc=tglx-hfZtesqFncYOwBW4kG4KsQ@public.gmane.org \
    --cc=tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org \
    --cc=torvalds-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org \
    --cc=viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.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).