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  1. 01 4月, 2009 4 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 8 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
    • T
      percpu: cosmetic renames in pcpu_setup_first_chunk() · 2441d15c
      由 Tejun Heo 提交于 
      Impact: cosmetic, preparation for future changes

Make the following renames in pcpur_setup_first_chunk() in preparation
for future changes.

* s/free_size/dyn_size/
* s/static_vm/first_vm/
* s/static_chunk/schunk/
Signed-off-by: NTejun Heo <tj@kernel.org>
      2441d15c
  29. 02 3月, 2009 1 次提交
    • I
      x86, mm: dont use non-temporal stores in pagecache accesses · f1800536
      由 Ingo Molnar 提交于 
      Impact: standardize IO on cached ops

On modern CPUs it is almost always a bad idea to use non-temporal stores,
as the regression in this commit has shown it:

  30d697fa: x86: fix performance regression in write() syscall

The kernel simply has no good information about whether using non-temporal
stores is a good idea or not - and trying to add heuristics only increases
complexity and inserts fragility.

The regression on cached write()s took very long to be found - over two
years. So dont take any chances and let the hardware decide how it makes
use of its caches.

The only exception is drivers/gpu/drm/i915/i915_gem.c: there were we are
absolutely sure that another entity (the GPU) will pick up the dirty
data immediately and that the CPU will not touch that data before the
GPU will.

Also, keep the _nocache() primitives to make it easier for people to
experiment with these details. There may be more clear-cut cases where
non-cached copies can be used, outside of filemap.c.

Cc: Salman Qazi <sqazi@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      f1800536
  31. 01 3月, 2009 2 次提交
    • T
      bootmem, x86: further fixes for arch-specific bootmem wrapping · d0c4f570
      由 Tejun Heo 提交于 
      Impact: fix new breakages introduced by previous fix

Commit c1329375 tried to clean up
bootmem arch wrapper but it wasn't quite correct.  Before the commit,
the followings were broken.

* Low level interface functions prefixed with __ ignored arch
  preference.

* reserve_bootmem(...) can't be mapped into
  reserve_bootmem_node(NODE_DATA(0)->bdata, ...) because the node is
  not preference here.  The region specified MUST fall into the
  specified region; otherwise, it will panic.

After the commit,

* If allocation fails for the arch preferred node, it should fallback
  to whatever is available.  Instead, it simply failed allocation.

There are too many internal details to allow generic wrapping and
still keep things simple for archs.  Plus, all that arch wants is a
way to prefer certain node over another.

This patch drops the generic wrapping around alloc_bootmem_core() and
add alloc_bootmem_core() instead.  If necessary, arch can define
bootmem_arch_referred_node() macro or function which takes all
allocation information and returns the preferred node.  bootmem
generic code will always try the preferred node first and then
fallback to other nodes as usual.

Breakages noted and changes reviewed by Johannes Weiner.
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
      d0c4f570
    • T
      percpu: kill compile warning in pcpu_populate_chunk() · 02d51fdf
      由 Tejun Heo 提交于 
      Impact: remove compile warning

Mark local variable map_end in pcpu_populate_chunk() with
uninitialized_var().  The variable is always used in tandem with
map_start and guaranteed to be initialized before use but gcc doesn't
understand that.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NIngo Molnar <mingo@elte.hu>
      02d51fdf
  33. 28 2月, 2009 2 次提交
    • V
      mm: fix lazy vmap purging (use-after-free error) · cbb76676
      由 Vegard Nossum 提交于 
      I just got this new warning from kmemcheck:

    WARNING: kmemcheck: Caught 32-bit read from freed memory (c7806a60)
    a06a80c7ecde70c1a04080c700000000a06709c1000000000000000000000000
     f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f f
     ^

    Pid: 0, comm: swapper Not tainted (2.6.29-rc4 #230)
    EIP: 0060:[<c1096df7>] EFLAGS: 00000286 CPU: 0
    EIP is at __purge_vmap_area_lazy+0x117/0x140
    EAX: 00070f43 EBX: c7806a40 ECX: c1677080 EDX: 00027b66
    ESI: 00002001 EDI: c170df0c EBP: c170df00 ESP: c178830c
     DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
    CR0: 80050033 CR2: c7806b14 CR3: 01775000 CR4: 00000690
    DR0: 00000000 DR1: 00000000 DR2: 00000000 DR3: 00000000
    DR6: 00004000 DR7: 00000000
     [<c1096f3e>] free_unmap_vmap_area_noflush+0x6e/0x70
     [<c1096f6a>] remove_vm_area+0x2a/0x70
     [<c1097025>] __vunmap+0x45/0xe0
     [<c10970de>] vunmap+0x1e/0x30
     [<c1008ba5>] text_poke+0x95/0x150
     [<c1008ca9>] alternatives_smp_unlock+0x49/0x60
     [<c171ef47>] alternative_instructions+0x11b/0x124
     [<c171f991>] check_bugs+0xbd/0xdc
     [<c17148c5>] start_kernel+0x2ed/0x360
     [<c171409e>] __init_begin+0x9e/0xa9
     [<ffffffff>] 0xffffffff

It happened here:

    $ addr2line -e vmlinux -i c1096df7
    mm/vmalloc.c:540

Code:

	list_for_each_entry(va, &valist, purge_list)
		__free_vmap_area(va);

It's this instruction:

    mov    0x20(%ebx),%edx

Which corresponds to a dereference of va->purge_list.next:

    (gdb) p ((struct vmap_area *) 0)->purge_list.next
    Cannot access memory at address 0x20

It seems that we should use "safe" list traversal here, as the element
is freed inside the loop. Please verify that this is the right fix.
Acked-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: <stable@kernel.org>		[2.6.28.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      cbb76676
    • N
      mm: vmap fix overflow · 7766970c
      由 Nick Piggin 提交于 
      The new vmap allocator can wrap the address and get confused in the case
of large allocations or VMALLOC_END near the end of address space.

Problem reported by Christoph Hellwig on a 32-bit XFS workload.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Reported-by: NChristoph Hellwig <hch@lst.de>
Cc: <stable@kernel.org>		[2.6.28.x]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      7766970c
  35. 26 2月, 2009 1 次提交
    • H
      shmem: fix shared anonymous accounting · 0b0a0806
      由 Hugh Dickins 提交于 
      Each time I exit Firefox, /proc/meminfo's Committed_AS goes down almost
400 kB: OVERCOMMIT_NEVER would be allowing overcommits it should
prohibit.

Commit fc8744ad "Stop playing silly
games with the VM_ACCOUNT flag" changed shmem_file_setup() to set the
shmem file's VM_ACCOUNT flag according to VM_NORESERVE not being set in
the vma flags; but did so only _after_ the shmem_acct_size(flags, size)
call which is expected to pre-account a shared anonymous object.

It's all clearer if we switch shmem.c over to use VM_NORESERVE
throughout in place of !VM_ACCOUNT.

But I very nearly sent in a patch which mistakenly removed the
accounting from tmpfs files: shmem_get_inode()'s memset was good for not
setting VM_ACCOUNT, but now it needs to set VM_NORESERVE.

Rather than setting that by default, then perhaps clearing it again in
shmem_file_setup(), let's pass it as a flag to shmem_get_inode(): that
allows us to remove the #ifdef CONFIG_SHMEM from shmem_file_setup().
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      0b0a0806
  37. 25 2月, 2009 3 次提交
  39. 24 2月, 2009 2 次提交
    • T
      percpu: add __read_mostly to variables which are mostly read only · 40150d37
      由 Tejun Heo 提交于 
      Most global variables in percpu allocator are initialized during boot
and read only from that point on.  Add __read_mostly as per Rusty's
suggestion.
Signed-off-by: NTejun Heo <tj@kernel.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
      40150d37
    • T
      percpu: give more latitude to arch specific first chunk initialization · 8d408b4b
      由 Tejun Heo 提交于 
      Impact: more latitude for first percpu chunk allocation

The first percpu chunk serves the kernel static percpu area and may or
may not contain extra room for further dynamic allocation.
Initialization of the first chunk needs to be done before normal
memory allocation service is up, so it has its own init path -
pcpu_setup_static().

It seems archs need more latitude while initializing the first chunk
for example to take advantage of large page mapping.  This patch makes
the following changes to allow this.

* Define PERCPU_DYNAMIC_RESERVE to give arch hint about how much space
  to reserve in the first chunk for further dynamic allocation.

* Rename pcpu_setup_static() to pcpu_setup_first_chunk().

* Make pcpu_setup_first_chunk() much more flexible by fetching page
  pointer by callback and adding optional @unit_size, @free_size and
  @base_addr arguments which allow archs to selectively part of chunk
  initialization to their likings.
Signed-off-by: NTejun Heo <tj@kernel.org>
      8d408b4b