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  1. 01 4月, 2009 16 次提交
  3. 31 3月, 2009 1 次提交
    • I
      lockdep: annotate reclaim context (__GFP_NOFS), fix SLOB · 19cefdff
      由 Ingo Molnar 提交于 
      Impact: build fix

fix typo in mm/slob.c:

 mm/slob.c:469: error: ‘flags’ undeclared (first use in this function)
 mm/slob.c:469: error: (Each undeclared identifier is reported only once
 mm/slob.c:469: error: for each function it appears in.)

Cc: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20090128135457.350751756@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      19cefdff
  5. 30 3月, 2009 2 次提交
  7. 27 3月, 2009 1 次提交
    • W
      writeback: double the dirty thresholds · 1b5e62b4
      由 Wu Fengguang 提交于 
      Enlarge default dirty ratios from 5/10 to 10/20.  This fixes [Bug
#12809] iozone regression with 2.6.29-rc6.

The iozone benchmarks are performed on a 1200M file, with 8GB ram.

  iozone -i 0 -i 1 -i 2 -i 3 -i 4 -r 4k -s 64k -s 512m -s 1200m -b tmp.xls
  iozone -B -r 4k -s 64k -s 512m -s 1200m -b tmp.xls

The performance regression is triggered by commit 1cf6e7d8(mm: task
dirty accounting fix), which makes more correct/thorough dirty
accounting.

The default 5/10 dirty ratios were picked (a) with the old dirty logic
and (b) largely at random and (c) designed to be aggressive.  In
particular, that (a) means that having fixed some of the dirty
accounting, maybe the real bug is now that it was always too aggressive,
just hidden by an accounting issue.

The enlarged 10/20 dirty ratios are just about enough to fix the regression.

[ We will have to look at how this affects the old fsync() latency issue,
  but that probably will need independent work.  - Linus ]

Cc: Nick Piggin <npiggin@suse.de>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Reported-by: N"Lin, Ming M" <ming.m.lin@intel.com>
Tested-by: N"Lin, Ming M" <ming.m.lin@intel.com>
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      1b5e62b4
  9. 26 3月, 2009 1 次提交
  11. 23 3月, 2009 2 次提交
  13. 16 3月, 2009 1 次提交
    • N
      highmem: atomic highmem kmap page pinning · 3297e760
      由 Nicolas Pitre 提交于 
      Most ARM machines have a non IO coherent cache, meaning that the
dma_map_*() set of functions must clean and/or invalidate the affected
memory manually before DMA occurs.  And because the majority of those
machines have a VIVT cache, the cache maintenance operations must be
performed using virtual
addresses.

When a highmem page is kunmap'd, its mapping (and cache) remains in place
in case it is kmap'd again. However if dma_map_page() is then called with
such a page, some cache maintenance on the remaining mapping must be
performed. In that case, page_address(page) is non null and we can use
that to synchronize the cache.

It is unlikely but still possible for kmap() to race and recycle the
virtual address obtained above, and use it for another page before some
on-going cache invalidation loop in dma_map_page() is done. In that case,
the new mapping could end up with dirty cache lines for another page,
and the unsuspecting cache invalidation loop in dma_map_page() might
simply discard those dirty cache lines resulting in data loss.

For example, let's consider this sequence of events:

	- dma_map_page(..., DMA_FROM_DEVICE) is called on a highmem page.

	-->	- vaddr = page_address(page) is non null. In this case
		it is likely that the page has valid cache lines
		associated with vaddr. Remember that the cache is VIVT.

		-->	for (i = vaddr; i < vaddr + PAGE_SIZE; i += 32)
				invalidate_cache_line(i);

	*** preemption occurs in the middle of the loop above ***

	- kmap_high() is called for a different page.

	-->	- last_pkmap_nr wraps to zero and flush_all_zero_pkmaps()
		  is called.  The pkmap_count value for the page passed
		  to dma_map_page() above happens to be 1, so the page
		  is unmapped.  But prior to that, flush_cache_kmaps()
		  cleared the cache for it.  So far so good.

		- A fresh pkmap entry is assigned for this kmap request.
		  The Murphy law says this pkmap entry will eventually
		  happen to use the same vaddr as the one which used to
		  belong to the other page being processed by
		  dma_map_page() in the preempted thread above.

	- The kmap_high() caller start dirtying the cache using the
	  just assigned virtual mapping for its page.

	*** the first thread is rescheduled ***

			- The for(...) loop is resumed, but now cached
			  data belonging to a different physical page is
			  being discarded !

And this is not only a preemption issue as ARM can be SMP as well,
making the above scenario just as likely. Hence the need for some kind
of pkmap page pinning which can be used in any context, primarily for
the benefit of dma_map_page() on ARM.

This provides the necessary interface to cope with the above issue if
ARCH_NEEDS_KMAP_HIGH_GET is defined, otherwise the resulting code is
unchanged.
Signed-off-by: NNicolas Pitre <nico@marvell.com>
Reviewed-by: NMinChan Kim <minchan.kim@gmail.com>
Acked-by: NAndrew Morton <akpm@linux-foundation.org>
      3297e760
  15. 15 3月, 2009 1 次提交
  17. 14 3月, 2009 1 次提交
  19. 13 3月, 2009 2 次提交
  21. 11 3月, 2009 1 次提交
  23. 10 3月, 2009 3 次提交
    • T
      percpu: generalize embedding first chunk setup helper · 66c3a757
      由 Tejun Heo 提交于 
      Impact: code reorganization

Separate out embedding first chunk setup helper from x86 embedding
first chunk allocator and put it in mm/percpu.c.  This will be used by
the default percpu first chunk allocator and possibly by other archs.
Signed-off-by: NTejun Heo <tj@kernel.org>
      66c3a757
    • T
      percpu: more flexibility for @dyn_size of pcpu_setup_first_chunk() · 6074d5b0
      由 Tejun Heo 提交于 
      Impact: cleanup, more flexibility for first chunk init

Non-negative @dyn_size used to be allowed iff @unit_size wasn't auto.
This restriction stemmed from implementation detail and made things a
bit less intuitive.  This patch allows @dyn_size to be specified
regardless of @unit_size and swaps the positions of @dyn_size and
@unit_size so that the parameter order makes more sense (static,
reserved and dyn sizes followed by enclosing unit_size).

While at it, add @unit_size >= PCPU_MIN_UNIT_SIZE sanity check.
Signed-off-by: NTejun Heo <tj@kernel.org>
      6074d5b0
    • T
      percpu: make x86 addr <-> pcpu ptr conversion macros generic · e0100983
      由 Tejun Heo 提交于 
      Impact: generic addr <-> pcpu ptr conversion macros

There's nothing arch specific about x86 __addr_to_pcpu_ptr() and
__pcpu_ptr_to_addr().  With proper __per_cpu_load and __per_cpu_start
defined, they'll do the right thing regardless of actual layout.

Move these macros from arch/x86/include/asm/percpu.h to mm/percpu.c
and allow archs to override it as necessary.
Signed-off-by: NTejun Heo <tj@kernel.org>
      e0100983
  25. 07 3月, 2009 1 次提交
    • T
      percpu: finer grained locking to break deadlock and allow atomic free · ccea34b5
      由 Tejun Heo 提交于 
      Impact: fix deadlock and allow atomic free

Percpu allocation always uses GFP_KERNEL and whole alloc/free paths
were protected by single mutex.  All percpu allocations have been from
GFP_KERNEL-safe context and the original allocator had this assumption
too.  However, by protecting both alloc and free paths with the same
mutex, the new allocator creates free -> alloc -> GFP_KERNEL
dependency which the original allocator didn't have.  This can lead to
deadlock if free is called from FS or IO paths.  Also, in general,
allocators are expected to allow free to be called from atomic
context.

This patch implements finer grained locking to break the deadlock and
allow atomic free.  For details, please read the "Synchronization
rules" comment.

While at it, also add CONTEXT: to function comments to describe which
context they expect to be called from and what they do to it.

This problem was reported by Thomas Gleixner and Peter Zijlstra.

  http://thread.gmane.org/gmane.linux.kernel/802384Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NThomas Gleixner <tglx@linutronix.de>
Reported-by: NPeter Zijlstra <peterz@infradead.org>
      ccea34b5
  27. 06 3月, 2009 7 次提交
    • T
      percpu: move fully free chunk reclamation into a work · a56dbddf
      由 Tejun Heo 提交于 
      Impact: code reorganization for later changes

Do fully free chunk reclamation using a work.  This change is to
prepare for locking changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
      a56dbddf
    • T
      percpu: move chunk area map extension out of area allocation · 9f7dcf22
      由 Tejun Heo 提交于 
      Impact: code reorganization for later changes

Separate out chunk area map extension into a separate function -
pcpu_extend_area_map() - and call it directly from pcpu_alloc() such
that pcpu_alloc_area() is guaranteed to have enough area map slots on
invocation.

With this change, pcpu_alloc_area() does only area allocation and the
only failure mode is when the chunk doens't have enough room, so
there's no need to distinguish it from memory allocation failures.
Make it return -1 on such cases instead of hacky -ENOSPC.
Signed-off-by: NTejun Heo <tj@kernel.org>
      9f7dcf22
    • T
      percpu: replace pcpu_realloc() with pcpu_mem_alloc() and pcpu_mem_free() · 1880d93b
      由 Tejun Heo 提交于 
      Impact: code reorganization for later changes

With static map handling moved to pcpu_split_block(), pcpu_realloc()
only clutters the code and it's also unsuitable for scheduled locking
changes.  Implement and use pcpu_mem_alloc/free() instead.
Signed-off-by: NTejun Heo <tj@kernel.org>
      1880d93b
    • T
      percpu, module: implement reserved allocation and use it for module percpu variables · edcb4639
      由 Tejun Heo 提交于 
      Impact: add reserved allocation functionality and use it for module
	percpu variables

This patch implements reserved allocation from the first chunk.  When
setting up the first chunk, arch can ask to set aside certain number
of bytes right after the core static area which is available only
through a separate reserved allocator.  This will be used primarily
for module static percpu variables on architectures with limited
relocation range to ensure that the module perpcu symbols are inside
the relocatable range.

If reserved area is requested, the first chunk becomes reserved and
isn't available for regular allocation.  If the first chunk also
includes piggy-back dynamic allocation area, a separate chunk mapping
the same region is created to serve dynamic allocation.  The first one
is called static first chunk and the second dynamic first chunk.
Although they share the page map, their different area map
initializations guarantee they serve disjoint areas according to their
purposes.

If arch doesn't setup reserved area, reserved allocation is handled
like any other allocation.
Signed-off-by: NTejun Heo <tj@kernel.org>
      edcb4639
    • T
      percpu: add an indirection ptr for chunk page map access · 3e24aa58
      由 Tejun Heo 提交于 
      Impact: allow sharing page map, no functional difference yet

Make chunk->page access indirect by adding a pointer and renaming the
actual array to page_ar.  This will be used by future changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
      3e24aa58
    • T
      percpu: use negative for auto for pcpu_setup_first_chunk() arguments · cafe8816
      由 Tejun Heo 提交于 
      Impact: argument semantic cleanup

In pcpu_setup_first_chunk(), zero @unit_size and @dyn_size meant
auto-sizing.  It's okay for @unit_size as 0 doesn't make sense but 0
dynamic reserve size is valid.  Alos, if arch @dyn_size is calculated
from other parameters, it might end up passing in 0 @dyn_size and
malfunction when the size is automatically adjusted.

This patch makes both @unit_size and @dyn_size ssize_t and use -1 for
auto sizing.
Signed-off-by: NTejun Heo <tj@kernel.org>
      cafe8816
    • T
      percpu: improve first chunk initial area map handling · 61ace7fa
      由 Tejun Heo 提交于 
      Impact: no functional change

When the first chunk is created, its initial area map is not allocated
because kmalloc isn't online yet.  The map is allocated and
initialized on the first allocation request on the chunk.  This works
fine but the scattering of initialization logic between the init
function and allocation path is a bit confusing.

This patch makes the first chunk initialize and use minimal statically
allocated map from pcpu_setpu_first_chunk().  The map resizing path
still needs to handle this specially but it's more straight-forward
and gives more latitude to the init path.  This will ease future
changes.
Signed-off-by: NTejun Heo <tj@kernel.org>
      61ace7fa