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  1. 24 Aug, 2009 1 commit
    • Hugh Dickins's avatar
      page_dup_rmap(), used on each mapped page when forking, was originally · 9787d456
      Hugh Dickins authored 
      just an inline atomic_inc of mapcount.  2.6.22 added CONFIG_DEBUG_VM
out-of-line checks to it, which would need to be ever-so-slightly
complicated to allow for the PageKsm() we're about to define.

But I think these checks never caught anything.  And if it's coding errors
we're worried about, such checks should be in page_remove_rmap() too, not
just when forking; whereas if it's pagetable corruption we're worried
about, then they shouldn't be limited to CONFIG_DEBUG_VM.

Oh, just revert page_dup_rmap() to an inline atomic_inc of mapcount.
Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarChris Wright <chrisw@redhat.com>
Signed-off-by: default avatarIzik Eidus <ieidus@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      9787d456
  3. 13 Aug, 2009 1 commit
    • Hugh Dickins's avatar
      This patch presents the mm interface to a dummy version of ksm.c, for · 58d5b7d3
      Hugh Dickins authored 
      better scrutiny of that interface: the real ksm.c follows later.

When CONFIG_KSM is not set, madvise(2) reject MADV_MERGEABLE and
MADV_UNMERGEABLE with EINVAL, since that seems more helpful than
pretending that they can be serviced.  But when CONFIG_KSM=y, accept them
even if KSM is not currently running, and even on areas which KSM will not
touch (e.g.  hugetlb or shared file or special driver mappings).

Like other madvices, report ENOMEM despite success if any area in the
range is unmapped, and use EAGAIN to report out of memory.

Define vma flag VM_MERGEABLE to identify an area on which KSM may try
merging pages: leave it to ksm_madvise() to decide whether to set it. 
Define mm flag MMF_VM_MERGEABLE to identify an mm which might contain
VM_MERGEABLE areas, to minimize callouts when forking or exiting.

Based upon earlier patches by Chris Wright and Izik Eidus.
Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarChris Wright <chrisw@redhat.com>
Signed-off-by: default avatarIzik Eidus <ieidus@redhat.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      58d5b7d3
  5. 22 Aug, 2009 1 commit
    • Hugh Dickins's avatar
      The out-of-tree KSM used ioctls on fds cloned from /dev/ksm to register a · 330d6131
      Hugh Dickins authored 
      memory area for merging: we prefer now to use an madvise(2) interface.

This patch just defines MADV_MERGEABLE (to tell KSM it may merge pages in
this area found identical to pages in other mergeable areas) and
MADV_UNMERGEABLE (to undo that).

Most architectures use asm-generic, but alpha, mips, parisc, xtensa need
their own definitions: included here for mmotm convenience, but we'll
probably want to split this and feed pieces to arch maintainers.

Based upon earlier patches by Chris Wright and Izik Eidus.
Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarChris Wright <chrisw@redhat.com>
Signed-off-by: default avatarIzik Eidus <ieidus@redhat.com>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Helge Deller <deller@gmx.de>
Cc: Chris Zankel <chris@zankel.net>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      330d6131
  7. 24 Aug, 2009 3 commits
    • Hugh Dickins's avatar
      madvise.c has several levels of switch statements, what to do in which? · 72eb3452
      Hugh Dickins authored 
      Move MADV_DOFORK code down from madvise_vma() to madvise_behavior(), so
madvise_vma() can be a simple router, to madvise_behavior() by default.

vma->vm_flags is an unsigned long so use the same type for new_flags.  Add
missing comment lines to describe MADV_DONTFORK and MADV_DOFORK.
Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: default avatarChris Wright <chrisw@redhat.com>
Signed-off-by: default avatarIzik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      72eb3452
    • Izik Eidus's avatar
      KSM is a linux driver that allows dynamicly sharing identical memory pages · 9923cb2a
      Izik Eidus authored 
      between one or more processes.

Unlike tradtional page sharing that is made at the allocation of the
memory, ksm do it dynamicly after the memory was created.  Memory is
periodically scanned; identical pages are identified and merged.

The sharing is made in a transparent way to the procsess that use it.

Ksm is highly important for hypervisors (kvm), where in production
enviorments there might be many copys of the same data data among the host
memory.  This kind of data can be: similar kernels, librarys, cache, and
so on.

Even that ksm was wrote for kvm, any userspace application that want to
use it to share its data can try it.

Ksm may be useful for any application that might have similar (page
aligment) data strctures among the memory, ksm will find this data merge
it to one copy, and even if it will be changed and thereforew copy on
writed, ksm will merge it again as soon as it will be identical again.

Another reason to consider using ksm is the fact that it might simplify
alot the userspace code of application that want to use shared private
data, instead that the application will mange shared area, ksm will do
this for the application, and even write to this data will be allowed
without any synchinization acts from the application.

Ksm was designed to be a loadable module that doesn't change the VM code
of linux.



This patch:

The set_pte_at_notify() macro allows setting a pte in the shadow page
table directly, instead of flushing the shadow page table entry and then
getting vmexit to set it.  It uses a new change_pte() callback to do so.

set_pte_at_notify() is an optimization for kvm, and other users of
mmu_notifiers, for COW pages.  It is useful for kvm when ksm is used,
because it allows kvm not to have to receive vmexit and only then map the
ksm page into the shadow page table, but instead map it directly at the
same time as Linux maps the page into the host page table.

Users of mmu_notifiers who don't implement new mmu_notifier_change_pte()
callback will just receive the mmu_notifier_invalidate_page() callback.
Signed-off-by: default avatarIzik Eidus <ieidus@redhat.com>
Signed-off-by: default avatarChris Wright <chrisw@redhat.com>
Signed-off-by: default avatarHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      9923cb2a
    • Johannes Weiner's avatar
      By the time PG_mlocked is cleared in the page freeing path, nobody else is · 848e1c4d
      Johannes Weiner authored 
      looking at our page->flags anymore.

It is thus safe to make the test-and-clear non-atomic and thereby removing
an unnecessary and expensive operation from a hotpath.
Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      848e1c4d
  9. 21 Jul, 2009 1 commit
  11. 24 Aug, 2009 7 commits
  13. 16 Jul, 2009 1 commit
  15. 24 Aug, 2009 1 commit
    • Rik van Riel's avatar
      When way too many processes go into direct reclaim, it is possible for all · 456a5e9f
      Rik van Riel authored 
      of the pages to be taken off the LRU.  One result of this is that the next
process in the page reclaim code thinks there are no reclaimable pages
left and triggers an out of memory kill.

One solution to this problem is to never let so many processes into the
page reclaim path that the entire LRU is emptied.  Limiting the system to
only having half of each inactive list isolated for reclaim should be
safe.
Signed-off-by: default avatarRik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      456a5e9f
  17. 16 Jul, 2009 1 commit
  19. 24 Aug, 2009 8 commits
  21. 14 Jul, 2009 1 commit
  23. 24 Aug, 2009 2 commits
  25. 17 Jul, 2009 1 commit
    • Lee Schermerhorn's avatar
      I noticed that alloc_bootmem_huge_page() will only advance to the next · 83d92902
      Lee Schermerhorn authored 
      node on failure to allocate a huge page, potentially filling nodes with
huge-pages.  I asked about this on linux-mm and linux-numa, cc'ing the
usual huge page suspects.

Mel Gorman responded:

	I strongly suspect that the same node being used until allocation
	failure instead of round-robin is an oversight and not deliberate
	at all. It appears to be a side-effect of a fix made way back in
	commit 63b4613c ["hugetlb: fix
	hugepage allocation with memoryless nodes"]. Prior to that patch
	it looked like allocations would always round-robin even when
	allocation was successful.

This patch--factored out of my "hugetlb mempolicy" series--moves the
advance of the hstate next node from which to allocate up before the test
for success of the attempted allocation.

Note that alloc_bootmem_huge_page() is only used for order > MAX_ORDER
huge pages.

I'll post a separate patch for mainline/stable, as the above mentioned
"balance freeing" series renamed the next node to alloc function.
Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: default avatarMel Gorman <mel@csn.ul.ie>
Reviewed-by: default avatarAndy Whitcroft <apw@canonical.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      83d92902
  27. 29 Jun, 2009 1 commit
  29. 30 Jun, 2009 1 commit
    • Lee Schermerhorn's avatar
      Fixes bug detected by libhugetlbfs test suite in: · 73c71f31
      Lee Schermerhorn authored 
      hugetlb-use-free_pool_huge_page-to-return-unused-surplus-pages.patch

Can't just "continue" for node with no surplus pages when returning
unused surplus.  We need to advance to 'next node to free'.

With this fix, the "hugetlb balance free across nodes" series passes
the test suite.
Signed-off-by: default avatarLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
      73c71f31
  31. 29 Jun, 2009 1 commit
  33. 24 Aug, 2009 1 commit
  35. 09 Sep, 2009 1 commit
  37. 24 Aug, 2009 1 commit
  39. 10 Aug, 2009 1 commit
  41. 29 Jun, 2009 1 commit
  43. 24 Aug, 2009 3 commits