Message-Id: <20080125055606.102986685@sgi.com>
User-Agent: quilt/0.46-1
Date: Thu, 24 Jan 2008 21:56:06 -0800
From: Christoph Lameter <clameter@sgi.com>
To: Andrea Arcangeli <andrea@qumranet.com>
Cc: Robin Holt <holt@sgi.com>, Avi Kivity <avi@qumranet.com>, Izik Eidus <izike@qumranet.com>,
Cc: Nick Piggin <npiggin@suse.de>,kvm-devel@lists.sourceforge.net
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>, Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Cc: daniel.blueman@quadrics.com, Hugh Dickins <hugh@veritas.com>
Subject-Prefix: [patch @num@/@total@]
Subject: [RFC] MMU Notifiers V2

This is a patchset implementing MMU notifier callbacks based on Andrea's
earlier work. These are needed if Linux pages are referenced from something
else than tracked by the rmaps of the kernel.

Issues:

- Feedback from uses of the callbacks for KVM, RDMA, XPmem and GRU

- RCU quiescent periods are required on registering and unregistering
  notifiers to guarantee visibility to other processors.
  Currently only mmu_notifier_release() does the correct thing.
  It is up to the user to provide RCU quiescent periods for
  register/unregister functions if they are called outside of the
  ->release method.


Andrea's mmu_notifier #4 -> RFC V1

- Merge subsystem rmap based with Linux rmap based approach
- Move Linux rmap based notifiers out of macro
- Try to account for what locks are held while the notifiers are
  called.
- Develop a patch sequence that separates out the different types of
  hooks so that we can review their use.
- Avoid adding include to linux/mm_types.h
- Integrate RCU logic suggested by Peter.

V1->V2:
- Improve RCU support
- Use mmap_sem for mmu_notifier register / unregister
- Drop invalidate_page from COW, mm/fremap.c and mm/rmap.c since we
  already have invalidate_range() callbacks there.
- Clean compile for !MMU_NOTIFIER
- Isolate filemap_xip strangeness into its own diff
- Pass a the flag to invalidate_range to indicate if a spinlock
  is held.
- Add invalidate_all()

--