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[PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread freezer

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This series is a followup to my proposal I brought up on Kernel Summit in 
Seoul. Noone seemed to had any principal objections, so let's have wider 
audience look into it.

In a nuthsell: freezing of kernel threads is horrible interface with 
unclear semantics and guarantees, and I am surprised it ever worked 
properly. Plus there are a lot of places that simply use it in a 
completely wrong way (which is not suprising, given the lack of defined 
semantics and requirements).

I've tested this over a series of suspend/resume cycles on several 
machines with at least ext4, btrfs and xfs, and it survived the testing 
without any harm.

Patch 1/3 	implements the actual change, and has a more detailed 
		explanation on "why?" and "how?" questions in the changelog

Patch 2/3	nukes all (hopefully) the calls to freezer from kthreads 
		in Linus' tree (as of 858e904bd71)

Patch 3/3	introduces WARN_ON() if anyone is trying to make use of 
		this again

Open questions / discussion points:

- is the way I am traversing list of superblocks backwards enough to 
  guarantee correct ordering? Especially: does this work as intended for 
  FUSE?

- should freezable workqueues be dealt with the same way? I haven't even 
  started to look into them in a serious way, but it seems like the 
  drivers that are making use of them would actually like to use proper
  PM callbacks instead

-- 
Jiri Kosina
SUSE Labs
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[PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Jiri Kosina <jikos@kernel.org> - 2015-10-30 14:50 +0100
  Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Alan Stern <stern@rowland.harvard.edu> - 2015-10-30 16:30 +0100
    Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Pavel Machek <pavel@ucw.cz> - 2015-10-30 18:50 +0100
      Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Jiri Kosina <jikos@kernel.org> - 2015-10-30 20:50 +0100
        Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Alan Stern <stern@rowland.harvard.edu> - 2015-10-30 21:50 +0100
          Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Jiri Kosina <jikos@kernel.org> - 2015-10-30 22:20 +0100
            Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread freezer "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-10-31 03:50 +0100
              Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Jiri Kosina <jikos@kernel.org> - 2015-10-31 09:20 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread freezer "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-11-02 03:20 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Jiri Kosina <jikos@kernel.org> - 2015-11-02 11:50 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Oliver Neukum <oneukum@suse.com> - 2015-11-02 12:10 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Alan Stern <stern@rowland.harvard.edu> - 2015-11-02 16:20 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Dave Chinner <david@fromorbit.com> - 2015-11-03 01:20 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread freezer "Rafael J. Wysocki" <rjw@rjwysocki.net> - 2015-11-03 04:40 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Jan Kara <jack@suse.cz> - 2015-11-03 10:50 +0100
                Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread freezer "Rafael J. Wysocki" <rafael@kernel.org> - 2015-11-03 22:40 +0100
              Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Alan Stern <stern@rowland.harvard.edu> - 2015-10-31 17:10 +0100
            Re: [PATCH 0/3] PM, vfs: use filesystem freezing instead of kthread  freezer Alan Stern <stern@rowland.harvard.edu> - 2015-10-31 17:00 +0100

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