linux/Documentation/vm
Pavel Emelyanov 541c237c09 pagemap: prepare to reuse constant bits with page-shift
In order to reuse bits from pagemap entries gracefully, we leave the
entries as is but on pagemap open emit a warning in dmesg, that bits
55-60 are about to change in a couple of releases.  Next, if a user
issues soft-dirty clear command via the clear_refs file (it was disabled
before v3.9) we assume that he's aware of the new pagemap format, note
that fact and report the bits in pagemap in the new manner.

The "migration strategy" looks like this then:

1. existing users are not affected -- they don't touch soft-dirty feature, thus
   see old bits in pagemap, but are warned and have time to fix themselves
2. those who use soft-dirty know about new pagemap format
3. some time soon we get rid of any signs of page-shift in pagemap as well as
   this trick with clear-soft-dirty affecting pagemap format.

Signed-off-by: Pavel Emelyanov <xemul@parallels.com>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Glauber Costa <glommer@parallels.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-03 16:07:26 -07:00
..
.gitignore Documentation/vm/.gitignore: add page-types 2009-09-24 07:20:57 -07:00
00-INDEX slub: doc: update the slabinfo.c file path 2011-08-31 20:10:17 +03:00
active_mm.txt Fix common misspellings 2011-03-31 11:26:23 -03:00
balance page allocator: use allocation flags as an index to the zone watermark 2009-06-16 19:47:35 -07:00
cleancache.txt Cleanups: rename of flush to invalidate, moving reporting of statistics 2012-03-22 19:52:47 -07:00
frontswap.txt doc: fix quite a few typos within Documentation 2012-11-19 14:28:24 +01:00
highmem.txt mm: highmem documentation 2010-10-26 16:52:08 -07:00
hugetlbpage.txt hugetlb: update hugetlbpage.txt 2012-08-21 16:45:03 -07:00
hwpoison.txt Documentation: update cgroupfs mount point 2011-06-15 21:52:50 -07:00
ksm.txt ksm: add some comments 2013-02-23 17:50:23 -08:00
locking mm: Convert i_mmap_lock to a mutex 2011-05-25 08:39:18 -07:00
numa doc: fix broken references 2011-09-27 18:08:04 +02:00
numa_memory_policy.txt Doc: Fix typo s/packages/packaged 2010-09-21 17:03:27 +02:00
overcommit-accounting mm: limit growth of 3% hardcoded other user reserve 2013-04-29 15:54:36 -07:00
page_migration trivial: fix where cgroup documentation is not correctly referred to 2009-03-30 15:22:02 +02:00
pagemap.txt pagemap: prepare to reuse constant bits with page-shift 2013-07-03 16:07:26 -07:00
slub.txt Documentations: Fix slabinfo.c directory in vm/slub.txt 2012-05-10 11:45:23 +03:00
soft-dirty.txt mm: soft-dirty bits for user memory changes tracking 2013-07-03 16:07:26 -07:00
transhuge.txt thp: introduce sysfs knob to disable huge zero page 2012-12-12 17:38:32 -08:00
unevictable-lru.txt mm: remove vma arg from page_evictable 2012-10-09 16:22:55 +09:00