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  1. 09 7月, 2011 3 次提交
    • M
      mm: vmscan: evaluate the watermarks against the correct classzone · da175d06
      由 Mel Gorman 提交于 
      When deciding if kswapd is sleeping prematurely, the classzone is taken
into account but this is different to what balance_pgdat() and the
allocator are doing.  Specifically, the DMA zone will be checked based on
the classzone used when waking kswapd which could be for a GFP_KERNEL or
GFP_HIGHMEM request.  The lowmem reserve limit kicks in, the watermark is
not met and kswapd thinks it's sleeping prematurely keeping kswapd awake in
error.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Reported-by: NPádraig Brady <P@draigBrady.com>
Tested-by: NPádraig Brady <P@draigBrady.com>
Tested-by: NAndrew Lutomirski <luto@mit.edu>
Acked-by: NRik van Riel <riel@redhat.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      da175d06
    • M
      mm: vmscan: do not apply pressure to slab if we are not applying pressure to zone · d7868dae
      由 Mel Gorman 提交于 
      During allocator-intensive workloads, kswapd will be woken frequently
causing free memory to oscillate between the high and min watermark.  This
is expected behaviour.

When kswapd applies pressure to zones during node balancing, it checks if
the zone is above a high+balance_gap threshold.  If it is, it does not
apply pressure but it unconditionally shrinks slab on a global basis which
is excessive.  In the event kswapd is being kept awake due to a high small
unreclaimable zone, it skips zone shrinking but still calls shrink_slab().

Once pressure has been applied, the check for zone being unreclaimable is
being made before the check is made if all_unreclaimable should be set.
This miss of unreclaimable can cause has_under_min_watermark_zone to be
set due to an unreclaimable zone preventing kswapd backing off on
congestion_wait().
Signed-off-by: NMel Gorman <mgorman@suse.de>
Reported-by: NPádraig Brady <P@draigBrady.com>
Tested-by: NPádraig Brady <P@draigBrady.com>
Tested-by: NAndrew Lutomirski <luto@mit.edu>
Acked-by: NRik van Riel <riel@redhat.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d7868dae
    • M
      mm: vmscan: correct check for kswapd sleeping in sleeping_prematurely · 08951e54
      由 Mel Gorman 提交于 
      During allocator-intensive workloads, kswapd will be woken frequently
causing free memory to oscillate between the high and min watermark.  This
is expected behaviour.  Unfortunately, if the highest zone is small, a
problem occurs.

This seems to happen most with recent sandybridge laptops but it's
probably a co-incidence as some of these laptops just happen to have a
small Normal zone.  The reproduction case is almost always during copying
large files that kswapd pegs at 100% CPU until the file is deleted or
cache is dropped.

The problem is mostly down to sleeping_prematurely() keeping kswapd awake
when the highest zone is small and unreclaimable and compounded by the
fact we shrink slabs even when not shrinking zones causing a lot of time
to be spent in shrinkers and a lot of memory to be reclaimed.

Patch 1 corrects sleeping_prematurely to check the zones matching
	the classzone_idx instead of all zones.

Patch 2 avoids shrinking slab when we are not shrinking a zone.

Patch 3 notes that sleeping_prematurely is checking lower zones against
	a high classzone which is not what allocators or balance_pgdat()
	is doing leading to an artifical belief that kswapd should be
	still awake.

Patch 4 notes that when balance_pgdat() gives up on a high zone that the
	decision is not communicated to sleeping_prematurely()

This problem affects 2.6.38.8 for certain and is expected to affect 2.6.39
and 3.0-rc4 as well.  If accepted, they need to go to -stable to be picked
up by distros and this series is against 3.0-rc4.  I've cc'd people that
reported similar problems recently to see if they still suffer from the
problem and if this fixes it.

This patch: correct the check for kswapd sleeping in sleeping_prematurely()

During allocator-intensive workloads, kswapd will be woken frequently
causing free memory to oscillate between the high and min watermark.  This
is expected behaviour.

A problem occurs if the highest zone is small.  balance_pgdat() only
considers unreclaimable zones when priority is DEF_PRIORITY but
sleeping_prematurely considers all zones.  It's possible for this sequence
to occur

  1. kswapd wakes up and enters balance_pgdat()
  2. At DEF_PRIORITY, marks highest zone unreclaimable
  3. At DEF_PRIORITY-1, ignores highest zone setting end_zone
  4. At DEF_PRIORITY-1, calls shrink_slab freeing memory from
        highest zone, clearing all_unreclaimable. Highest zone
        is still unbalanced
  5. kswapd returns and calls sleeping_prematurely
  6. sleeping_prematurely looks at *all* zones, not just the ones
     being considered by balance_pgdat. The highest small zone
     has all_unreclaimable cleared but the zone is not
     balanced. all_zones_ok is false so kswapd stays awake

This patch corrects the behaviour of sleeping_prematurely to check the
zones balance_pgdat() checked.
Signed-off-by: NMel Gorman <mgorman@suse.de>
Reported-by: NPádraig Brady <P@draigBrady.com>
Tested-by: NPádraig Brady <P@draigBrady.com>
Tested-by: NAndrew Lutomirski <luto@mit.edu>
Acked-by: NRik van Riel <riel@redhat.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      08951e54
  3. 28 6月, 2011 7 次提交
    • K
      memcg: fix direct softlimit reclaim to be called in limit path · ac34a1a3
      由 KAMEZAWA Hiroyuki 提交于 
      Commit d149e3b2 ("memcg: add the soft_limit reclaim in global direct
reclaim") adds a softlimit hook to shrink_zones().  By this, soft limit
is called as

   try_to_free_pages()
       do_try_to_free_pages()
           shrink_zones()
               mem_cgroup_soft_limit_reclaim()

Then, direct reclaim is memcg softlimit hint aware, now.

But, the memory cgroup's "limit" path can call softlimit shrinker.

   try_to_free_mem_cgroup_pages()
       do_try_to_free_pages()
           shrink_zones()
               mem_cgroup_soft_limit_reclaim()

This will cause a global reclaim when a memcg hits limit.

This is bug. soft_limit_reclaim() should be called when
scanning_global_lru(sc) == true.

And the commit adds a variable "total_scanned" for counting softlimit
scanned pages....it's not "total".  This patch removes the variable and
update sc->nr_scanned instead of it.  This will affect shrink_slab()'s
scan condition but, global LRU is scanned by softlimit and I think this
change makes sense.

TODO: avoid too much scanning of a zone when softlimit did enough work.
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Ying Han <yinghan@google.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      ac34a1a3
    • J
      mm: fix assertion mapping->nrpages == 0 in end_writeback() · 08142579
      由 Jan Kara 提交于 
      Under heavy memory and filesystem load, users observe the assertion
mapping->nrpages == 0 in end_writeback() trigger.  This can be caused by
page reclaim reclaiming the last page from a mapping in the following
race:

	CPU0				CPU1
  ...
  shrink_page_list()
    __remove_mapping()
      __delete_from_page_cache()
        radix_tree_delete()
					evict_inode()
					  truncate_inode_pages()
					    truncate_inode_pages_range()
					      pagevec_lookup() - finds nothing
					  end_writeback()
					    mapping->nrpages != 0 -> BUG
        page->mapping = NULL
        mapping->nrpages--

Fix the problem by doing a reliable check of mapping->nrpages under
mapping->tree_lock in end_writeback().

Analyzed by Jay <jinshan.xiong@whamcloud.com>, lost in LKML, and dug out
by Miklos Szeredi <mszeredi@suse.de>.

Cc: Jay <jinshan.xiong@whamcloud.com>
Cc: Miklos Szeredi <mszeredi@suse.de>
Signed-off-by: NJan Kara <jack@suse.cz>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      08142579
    • P
      mm/memory-failure.c: fix spinlock vs mutex order · 9b679320
      由 Peter Zijlstra 提交于 
      We cannot take a mutex while holding a spinlock, so flip the order and
fix the locking documentation.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      9b679320
    • H
      tmpfs: add shmem_read_mapping_page_gfp · d9d90e5e
      由 Hugh Dickins 提交于 
      Although it is used (by i915) on nothing but tmpfs, read_cache_page_gfp()
is unsuited to tmpfs, because it inserts a page into pagecache before
calling the filesystem's ->readpage: tmpfs may have pages in swapcache
which only it knows how to locate and switch to filecache.

At present tmpfs provides a ->readpage method, and copes with this by
copying pages; but soon we can simplify it by removing its ->readpage.
Provide shmem_read_mapping_page_gfp() now, ready for that transition,

Export shmem_read_mapping_page_gfp() and add it to list in shmem_fs.h,
with shmem_read_mapping_page() inline for the common mapping_gfp case.

(shmem_read_mapping_page_gfp or shmem_read_cache_page_gfp? Generally the
read_mapping_page functions use the mapping's ->readpage, and the
read_cache_page functions use the supplied filler, so I think
read_cache_page_gfp was slightly misnamed.)
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      d9d90e5e
    • H
      tmpfs: take control of its truncate_range · 94c1e62d
      由 Hugh Dickins 提交于 
      2.6.35's new truncate convention gave tmpfs the opportunity to control
its file truncation, no longer enforced from outside by vmtruncate().
We shall want to build upon that, to handle pagecache and swap together.

Slightly redefine the ->truncate_range interface: let it now be called
between the unmap_mapping_range()s, with the filesystem responsible for
doing the truncate_inode_pages_range() from it - just as the filesystem
is nowadays responsible for doing that from its ->setattr.

Let's rename shmem_notify_change() to shmem_setattr().  Instead of
calling the generic truncate_setsize(), bring that code in so we can
call shmem_truncate_range() - which will later be updated to perform its
own variant of truncate_inode_pages_range().

Remove the punch_hole unmap_mapping_range() from shmem_truncate_range():
now that the COW's unmap_mapping_range() comes after ->truncate_range,
there is no need to call it a third time.

Export shmem_truncate_range() and add it to the list in shmem_fs.h, so
that i915_gem_object_truncate() can call it explicitly in future; get
this patch in first, then update drm/i915 once this is available (until
then, i915 will just be doing the truncate_inode_pages() twice).

Though introduced five years ago, no other filesystem is implementing
->truncate_range, and its only other user is madvise(,,MADV_REMOVE): we
expect to convert it to fallocate(,FALLOC_FL_PUNCH_HOLE,,) shortly,
whereupon ->truncate_range can be removed from inode_operations -
shmem_truncate_range() will help i915 across that transition too.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      94c1e62d
    • H
      mm: move shmem prototypes to shmem_fs.h · 072441e2
      由 Hugh Dickins 提交于 
      Before adding any more global entry points into shmem.c, gather such
prototypes into shmem_fs.h.  Remove mm's own declarations from swap.h,
but for now leave the ones in mm.h: because shmem_file_setup() and
shmem_zero_setup() are called from various places, and we should not
force other subsystems to update immediately.
Signed-off-by: NHugh Dickins <hughd@google.com>
Cc: Christoph Hellwig <hch@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      072441e2
    • H
      mm: move vmtruncate_range to truncate.c · 5b8ba101
      由 Hugh Dickins 提交于 
      You would expect to find vmtruncate_range() next to vmtruncate() in
mm/truncate.c: move it there.
Signed-off-by: NHugh Dickins <hughd@google.com>
Acked-by: NChristoph Hellwig <hch@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5b8ba101
  5. 23 6月, 2011 2 次提交
  7. 18 6月, 2011 3 次提交
    • L
      mm: avoid anon_vma_chain allocation under anon_vma lock · dd34739c
      由 Linus Torvalds 提交于 
      Hugh Dickins points out that lockdep (correctly) spots a potential
deadlock on the anon_vma lock, because we now do a GFP_KERNEL allocation
of anon_vma_chain while doing anon_vma_clone().  The problem is that
page reclaim will want to take the anon_vma lock of any anonymous pages
that it will try to reclaim.

So re-organize the code in anon_vma_clone() slightly: first do just a
GFP_NOWAIT allocation, which will usually work fine.  But if that fails,
let's just drop the lock and re-do the allocation, now with GFP_KERNEL.

End result: not only do we avoid the locking problem, this also ends up
getting better concurrency in case the allocation does need to block.
Tim Chen reports that with all these anon_vma locking tweaks, we're now
almost back up to the spinlock performance.
Reported-and-tested-by: NHugh Dickins <hughd@google.com>
Tested-by: NTim Chen <tim.c.chen@linux.intel.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      dd34739c
    • P
      mm: avoid repeated anon_vma lock/unlock sequences in unlink_anon_vmas() · eee2acba
      由 Peter Zijlstra 提交于 
      This matches the anon_vma_clone() case, and uses the same lock helper
functions.  Because of the need to potentially release the anon_vma's,
it's a bit more complex, though.

We traverse the 'vma->anon_vma_chain' in two phases: the first loop gets
the anon_vma lock (with the helper function that only takes the lock
once for the whole loop), and removes any entries that don't need any
more processing.

The second phase just traverses the remaining list entries (without
holding the anon_vma lock), and does any actual freeing of the
anon_vma's that is required.
Signed-off-by: NPeter Zijlstra <peterz@infradead.org>
Tested-by: NHugh Dickins <hughd@google.com>
Tested-by: NTim Chen <tim.c.chen@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      eee2acba
    • L
      mm: avoid repeated anon_vma lock/unlock sequences in anon_vma_clone() · bb4aa396
      由 Linus Torvalds 提交于 
      In anon_vma_clone() we traverse the vma->anon_vma_chain of the source
vma, locking the anon_vma for each entry.

But they are all going to have the same root entry, which means that
we're locking and unlocking the same lock over and over again.  Which is
expensive in locked operations, but can get _really_ expensive when that
root entry sees any kind of lock contention.

In fact, Tim Chen reports a big performance regression due to this: when
we switched to use a mutex instead of a spinlock, the contention case
gets much worse.

So to alleviate this all, this commit creates a small helper function
(lock_anon_vma_root()) that can be used to take the lock just once
rather than taking and releasing it over and over again.

We still have the same "take the lock and release" it behavior in the
exit path (in unlink_anon_vmas()), but that one is a bit harder to fix
since we're actually freeing the anon_vma entries as we go, and that
will touch the lock too.
Reported-and-tested-by: NTim Chen <tim.c.chen@linux.intel.com>
Tested-by: NHugh Dickins <hughd@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      bb4aa396
  9. 17 6月, 2011 1 次提交
  11. 16 6月, 2011 21 次提交
  13. 06 6月, 2011 1 次提交
  15. 04 6月, 2011 2 次提交
    • A
      more conservative S_NOSEC handling · 9e1f1de0
      由 Al Viro 提交于 
      Caching "we have already removed suid/caps" was overenthusiastic as merged.
On network filesystems we might have had suid/caps set on another client,
silently picked by this client on revalidate, all of that *without* clearing
the S_NOSEC flag.

AFAICS, the only reasonably sane way to deal with that is
	* new superblock flag; unless set, S_NOSEC is not going to be set.
	* local block filesystems set it in their ->mount() (more accurately,
mount_bdev() does, so does btrfs ->mount(), users of mount_bdev() other than
local block ones clear it)
	* if any network filesystem (or a cluster one) wants to use S_NOSEC,
it'll need to set MS_NOSEC in sb->s_flags *AND* take care to clear S_NOSEC when
inode attribute changes are picked from other clients.

It's not an earth-shattering hole (anybody that can set suid on another client
will almost certainly be able to write to the file before doing that anyway),
but it's a bug that needs fixing.
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>
      9e1f1de0
    • S
      SLAB: Record actual last user of freed objects. · a947eb95
      由 Suleiman Souhlal 提交于 
      Currently, when using CONFIG_DEBUG_SLAB, we put in kfree() or
kmem_cache_free() as the last user of free objects, which is not
very useful, so change it to the caller of those functions instead.
Acked-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NSuleiman Souhlal <suleiman@google.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>
      a947eb95