There are many places where we need to determine the node of a zone.
Currently we use a difficult to read sequence of pointer dereferencing.
Put that into an inline function and use throughout VM.  Maybe we can find
a way to optimize the lookup in the future.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

I found two location in hugetlb.c where we chase pointer instead of using
page_to_nid().  Page_to_nid is more effective and can get the node directly
from page flags.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Update the comments for __oom_kill_task() to reflect the code changes.
Signed-off-by: NRam Gupta <r.gupta@astronautics.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Minor performance fix.

If we reclaimed enough slab pages from a zone then we can avoid going off
node with the current allocation.  Take care of updating nr_reclaimed when
reclaiming from the slab.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Currently one can enable slab reclaim by setting an explicit option in
/proc/sys/vm/zone_reclaim_mode.  Slab reclaim is then used as a final
option if the freeing of unmapped file backed pages is not enough to free
enough pages to allow a local allocation.

However, that means that the slab can grow excessively and that most memory
of a node may be used by slabs.  We have had a case where a machine with
46GB of memory was using 40-42GB for slab.  Zone reclaim was effective in
dealing with pagecache pages.  However, slab reclaim was only done during
global reclaim (which is a bit rare on NUMA systems).

This patch implements slab reclaim during zone reclaim.  Zone reclaim
occurs if there is a danger of an off node allocation.  At that point we

1. Shrink the per node page cache if the number of pagecache
   pages is more than min_unmapped_ratio percent of pages in a zone.

2. Shrink the slab cache if the number of the nodes reclaimable slab pages
   (patch depends on earlier one that implements that counter)
   are more than min_slab_ratio (a new /proc/sys/vm tunable).

The shrinking of the slab cache is a bit problematic since it is not node
specific.  So we simply calculate what point in the slab we want to reach
(current per node slab use minus the number of pages that neeed to be
allocated) and then repeately run the global reclaim until that is
unsuccessful or we have reached the limit.  I hope we will have zone based
slab reclaim at some point which will make that easier.

The default for the min_slab_ratio is 5%

Also remove the slab option from /proc/sys/vm/zone_reclaim_mode.

[akpm@osdl.org: cleanups]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove the atomic counter for slab_reclaim_pages and replace the counter
and NR_SLAB with two ZVC counter that account for unreclaimable and
reclaimable slab pages: NR_SLAB_RECLAIMABLE and NR_SLAB_UNRECLAIMABLE.

Change the check in vmscan.c to refer to to NR_SLAB_RECLAIMABLE.  The
intend seems to be to check for slab pages that could be freed.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

*_pages is a better description of the role of the variable.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The allocpercpu functions __alloc_percpu and __free_percpu() are heavily
using the slab allocator.  However, they are conceptually slab.  This also
simplifies SLOB (at this point slob may be broken in mm.  This should fix
it).
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

If a zone is unpopulated then we do not need to check for pages that are to
be drained and also not for vm counters that may need to be updated.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Free one_page currently adds the page to a fake list and calls
free_page_bulk.  Fee_page_bulk takes it off again and then calles
__free_one_page.

Make free_one_page go directly to __free_one_page.  Saves list on / off and
a temporary list in free_one_page for higher ordered pages.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

One of the changes necessary for shared page tables is to standardize the
pxx_page macros.  pte_page and pmd_page have always returned the struct
page associated with their entry, while pte_page_kernel and pmd_page_kernel
have returned the kernel virtual address.  pud_page and pgd_page, on the
other hand, return the kernel virtual address.

Shared page tables needs pud_page and pgd_page to return the actual page
structures.  There are very few actual users of these functions, so it is
simple to standardize their usage.

Since this is basic cleanup, I am submitting these changes as a standalone
patch.  Per Hugh Dickins' comments about it, I am also changing the
pxx_page_kernel macros to pxx_page_vaddr to clarify their meaning.
Signed-off-by: NDave McCracken <dmccr@us.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

On High end systems (1024 or so cpus) this can potentially cause stack
overflow. Fix the stack usage.
Signed-off-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In many places we will need to use the same combination of flags.  Specify
a single GFP_THISNODE definition for ease of use in gfp.h.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Profiling really suffers with off node buffers.  Fail if no memory is
available on the nodes.  The profiling code can deal with these failures
should they occur.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

There are frequent references to *z in get_page_from_freelist.

Add an explicit zone variable that can be used in all these places.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The uncached allocator manages per node pools.  Specify __GFP_THISNODE in
order to force allocation on the indicated node or fail.  The uncached
allocator has already logic to deal with failing allocations.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

If the user specified a node where we should move the page to then we
really do not want any other node.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

[PATCH] Add __GFP_THISNODE to avoid fallback to other nodes and ignore cpuset/memory policy restrictions

Add a new gfp flag __GFP_THISNODE to avoid fallback to other nodes.  This
flag is essential if a kernel component requires memory to be located on a
certain node.  It will be needed for alloc_pages_node() to force allocation
on the indicated node and for alloc_pages() to force allocation on the
current node.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Place the alien array cache locks of on slab malloc slab caches on a
seperate lockdep class.  This avoids false positives from lockdep

[akpm@osdl.org: build fix]
Signed-off-by: NRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: NShai Fultheim <shai@scalex86.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

It is fairly easy to get a system to oops by simply sizing a cache via
/proc in such a way that one of the chaches (shared is easiest) becomes
bigger than the maximum allowed slab allocation size.  This occurs because
enable_cpucache() fails if it cannot reallocate some caches.

However, enable_cpucache() is used for multiple purposes: resizing caches,
cache creation and bootstrap.

If the slab is already up then we already have working caches.  The resize
can fail without a problem.  We just need to return the proper error code.
F.e.  after this patch:

# echo "size-64 10000 50 1000" >/proc/slabinfo
-bash: echo: write error: Cannot allocate memory

notice no OOPS.

If we are doing a kmem_cache_create() then we also should not panic but
return -ENOMEM.

If on the other hand we do not have a fully bootstrapped slab allocator yet
then we should indeed panic since we are unable to bring up the slab to its
full functionality.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The ability to free memory allocated to a slab cache is also useful if an
error occurs during setup of a slab.  So extract the function.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

[akpm@osdl.org: export fix]
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Acked-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Let's try to keep mm/ comments more useful and up to date. This is a start.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Also, checks if we get a valid slabp_cache for off slab slab-descriptors.
We should always get this.  If we don't, then in that case we, will have to
disable off-slab descriptors for this cache and do the calculations again.
This is a rare case, so add a BUG_ON, for now, just in case.
Signed-off-by: NAlok N Kataria <alok.kataria@calsoftinc.com>
Signed-off-by: NRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: NShai Fultheim <shai@scalex86.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Introduce ARCH_LOW_ADDRESS_LIMIT which can be set per architecture to
override the 4GB default limit used by the bootmem allocater within
__alloc_bootmem_low() and __alloc_bootmem_low_node().  E.g.  s390 needs a
2GB limit instead of 4GB.
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Print the name of the task invoking the OOM killer.  Could make debugging
easier.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Skip kernel threads, rather than having them return 0 from badness.
Theoretically, badness might truncate all results to 0, thus a kernel thread
might be picked first, causing an infinite loop.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

PF_SWAPOFF processes currently cause select_bad_process to return straight
away.  Instead, give them high priority, so we will kill them first, however
we also first ensure no parallel OOM kills are happening at the same time.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Having the oomkilladj == OOM_DISABLE check before the releasing check means
that oomkilladj == OOM_DISABLE tasks exiting will not stop the OOM killer.

Moving the test down will give the desired behaviour.  Also: it will allow
them to "OOM-kill" themselves if they are exiting.  As per the previous patch,
this is required to prevent OOM killer deadlocks (and they don't actually get
killed, because they're already exiting -- they're simply allowed access to
memory reserves).
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

If current *is* exiting, it should actually be allowed to access reserved
memory rather than OOM kill something else.  Can't do this via a straight
check in page_alloc.c because that would allow multiple tasks to use up
reserves.  Instead cause current to OOM-kill itself which will mark it as
TIF_MEMDIE.

The current procedure of simply aborting the OOM-kill if a task is exiting can
lead to OOM deadlocks.

In the case of killing a PF_EXITING task, don't make a lot of noise about it.
This becomes more important in future patches, where we can "kill" OOM_DISABLE
tasks.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

cpuset_excl_nodes_overlap does not always indicate that killing a task will
not free any memory we for us.  For example, we may be asking for an
allocation from _anywhere_ in the machine, or the task in question may be
pinning memory that is outside its cpuset.  Fix this by just causing
cpuset_excl_nodes_overlap to reduce the badness rather than disallow it.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NPaul Jackson <pj@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Potentially it takes several scans of the lru lists before we can even start
reclaiming pages.

mapped pages, with young ptes can take 2 passes on the active list + one on
the inactive list.  But reclaim_mapped may not always kick in instantly, so it
could take even more than that.

Raise the threshold for marking a zone as all_unreclaimable from a factor of 4
time the pages in the zone to 6.  Introduce a mechanism to force
reclaim_mapped if we've reached a factor 3 and still haven't made progress.

Previously, a customer doing stress testing was able to easily OOM the box
after using only a small fraction of its swap (~100MB).  After the patches, it
would only OOM after having used up all swap (~800MB).
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

__alloc_pages currently starts shooting if page reclaim has failed to free up
swap_cluster_max pages in one run through the priorities.  This is not always
a good indicator on its own, so make use of the all_unreclaimable logic as
well: don't consider going OOM until all zones we're interested in are
unreclaimable.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Currently we can silently drop data if the write to swap failed.  It
usually doesn't result in data-corruption because on page-in the process
will receive SIGBUS (assuming write-failure implies read-failure).

This assumption might or might not be valid.

This patch will avoid the page being discarded after a failed write.  But
will print a warning the sysadmin _should_ take to heart, if a lot of swap
space becomes un-writeable, OOM is not far off.

Tested by making the write fail 'randomly' once every 50 writes or so.

[akpm@osdl.org: printk warning fix]
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

As explained by Heiko, on s390 (32-bit) ARCH_KMALLOC_MINALIGN is set to
eight because their common I/O layer allocates data structures that need to
have an eight byte alignment.  This does not work when CONFIG_SLAB_DEBUG is
enabled because kmem_cache_create will override alignment to BYTES_PER_WORD
which is four.

So change kmem_cache_create to ensure cache alignment is always at minimum
what the architecture or caller mandates even if slab debugging is enabled.

Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

lock_page needs the caller to have a reference on the page->mapping inode
due to sync_page, ergo set_page_dirty_lock is obviously buggy according to
its comments.

Solve it by introducing a new lock_page_nosync which does not do a sync_page.

akpm: unpleasant solution to an unpleasant problem.  If it goes wrong it could
cause great slowdowns while the lock_page() caller waits for kblockd to
perform the unplug.  And if a filesystem has special sync_page() requirements
(none presently do), permanent hangs are possible.

otoh, set_page_dirty_lock() is usually (always?) called against userspace
pages.  They are always up-to-date, so there shouldn't be any pending read I/O
against these pages.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Some users of remove_mapping had been unsafe.

Modify the remove_mapping precondition to ensure the caller has locked the
page and obtained the correct mapping.  Modify callers to ensure the
mapping is the correct one.

[hugh@veritas.com: swapper_space fix]
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

These functions are already documented quite well with long comments.  Now
add kerneldoc style header to make this turn up in everyones favorite doc
format.
Signed-off-by: NRolf Eike Beer <eike-kernel@sf-tec.de>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch splits alloc_percpu() up into two phases.  Likewise for
free_percpu().  This allows clients to limit initial allocations to online
cpu's, and to populate or depopulate per-cpu data at run time as needed:

  struct my_struct *obj;

  /* initial allocation for online cpu's */
  obj = percpu_alloc(sizeof(struct my_struct), GFP_KERNEL);

  ...

  /* populate per-cpu data for cpu coming online */
  ptr = percpu_populate(obj, sizeof(struct my_struct), GFP_KERNEL, cpu);

  ...

  /* access per-cpu object */
  ptr = percpu_ptr(obj, smp_processor_id());

  ...

  /* depopulate per-cpu data for cpu going offline */
  percpu_depopulate(obj, cpu);

  ...

  /* final removal */
  percpu_free(obj);
Signed-off-by: NMartin Peschke <mp3@de.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add a notifer chain to the out of memory killer.  If one of the registered
callbacks could release some memory, do not kill the process but return and
retry the allocation that forced the oom killer to run.

The purpose of the notifier is to add a safety net in the presence of
memory ballooners.  If the resource manager inflated the balloon to a size
where memory allocations can not be satisfied anymore, it is better to
deflate the balloon a bit instead of killing processes.

The implementation for the s390 ballooner is included.

[akpm@osdl.org: cleanups]
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>