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Some oprofile results obtained while using tbench on a 2x2 cpu machine were
very surprising.
For example, loopback_xmit() function was using high number of cpu cycles
to perform the statistic updates, supposed to be real cheap since they use
percpu data
pcpu_lstats = netdev_priv(dev);
lb_stats = per_cpu_ptr(pcpu_lstats, smp_processor_id());
lb_stats->packets++; /* HERE : serious contention */
lb_stats->bytes += skb->len;
struct pcpu_lstats is a small structure containing two longs. It appears
that on my 32bits platform, alloc_percpu(8) allocates a single cache line,
instead of giving to each cpu a separate cache line.
Using the following patch gave me impressive boost in various benchmarks
( 6 % in tbench)
(all percpu_counters hit this bug too)
Long term fix (ie >= 2.6.26) would be to let each CPU allocate their own
block of memory, so that we dont need to roudup sizes to L1_CACHE_BYTES, or
merging the SGI stuff of course...
Note : SLUB vs SLAB is important here to *show* the improvement, since they
dont have the same minimum allocation sizes (8 bytes vs 32 bytes). This
could very well explain regressions some guys reported when they switched
to SLUB.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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jiffies subtraction may cause an overflow problem. It should be using
time_after().
[akpm@linux-foundation.org: include jiffies.h]
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This patch fix possible NULL pointer dereference if kzalloc
failed. To be able to return proper error code the function
return type is changed to ssize_t (according to callees and
sysfs definitions).
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Slub is missing some NUMA support for large kmallocs. Provide that.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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We only need to look up object from c->page->freelist once in
__slab_alloc().
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Provide comments and fix up various spelling / style issues.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Group SLUB_DEBUG code together to reduce the number of #ifdefs. Move some
debug checks under the #ifdef.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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The BUG_ONs are useless since the pointer derefs will lead to
NULL deref errors anyways. Some of the checks are not necessary
if no debugging is possible.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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No need to access the kmem_cache structure. We have the same value
in kmem_cache_cpu.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Alloc debug processing is never called with a NULL object pointer.
No reason to check for NULL.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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There is no page->offset anymore and also no associated limit on the number
of objects. The page->offset field was removed for 2.6.24. So the check
in kmem_cache_flags() is now also obsolete (should have been dropped
earlier, somehow a hunk vanished).
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-by: Christoph Lameter <clameter@sgi.com>
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The sysfs callback is better named show_slab_objects since it is always
called from the xxx_show callbacks. We need the name for other purposes
later.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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This only made sense for the alternate fastpath which was reverted last week.
Mathieu is working on a new version that addresses the fastpath issues but that
new code first needs to go through mm and it is not clear if we need the
unique end pointers with his new scheme.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Fix docbook problems in kernel-api.tmpl.
These cause the generated docbook to be incorrect.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Cgroup requires the subsystem to return negative error code on error in the
create method.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Remove this VM_BUG_ON(), as Balbir stated:
We used to have a for loop with !list_empty() as a termination condition
and VM_BUG_ON(!pc) is a spill over. With the new loop, VM_BUG_ON(!pc) does
not make sense.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Balbir Singh <balbir@in.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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WARNING: vmlinux.o(.meminit.text+0x649):
Section mismatch in reference from the
function free_area_init_core() to the function .init.text:setup_usemap()
The function __meminit free_area_init_core() references
a function __init setup_usemap().
If free_area_init_core is only used by setup_usemap then
annotate free_area_init_core with a matching annotation.
The warning is covers this stack of functions in mm/page_alloc.c:
alloc_bootmem_node must be marked __init.
alloc_bootmem_node is used by setup_usemap, if !SPARSEMEM.
(usemap_size is only used by setup_usemap, if !SPARSEMEM.)
setup_usemap is only used by free_area_init_core.
free_area_init_core is only used by free_area_init_node.
free_area_init_node is used by:
arch/alpha/mm/numa.c: __init paging_init()
arch/arm/mm/init.c: __init bootmem_init_node()
arch/avr32/mm/init.c: __init paging_init()
arch/cris/arch-v10/mm/init.c: __init paging_init()
arch/cris/arch-v32/mm/init.c: __init paging_init()
arch/m32r/mm/discontig.c: __init zone_sizes_init()
arch/m32r/mm/init.c: __init zone_sizes_init()
arch/m68k/mm/motorola.c: __init paging_init()
arch/m68k/mm/sun3mmu.c: __init paging_init()
arch/mips/sgi-ip27/ip27-memory.c: __init paging_init()
arch/parisc/mm/init.c: __init paging_init()
arch/sparc/mm/srmmu.c: __init srmmu_paging_init()
arch/sparc/mm/sun4c.c: __init sun4c_paging_init()
arch/sparc64/mm/init.c: __init paging_init()
mm/page_alloc.c: __init free_area_init_nodes()
mm/page_alloc.c: __init free_area_init()
and
mm/memory_hotplug.c: hotadd_new_pgdat()
hotadd_new_pgdat can not be an __init function, but:
It is compiled for MEMORY_HOTPLUG configurations only
MEMORY_HOTPLUG depends on SPARSEMEM || X86_64_ACPI_NUMA
X86_64_ACPI_NUMA depends on X86_64
ARCH_FLATMEM_ENABLE depends on X86_32
ARCH_DISCONTIGMEM_ENABLE depends on X86_32
So X86_64_ACPI_NUMA implies SPARSEMEM, right?
So we can mark the stack of functions __init for !SPARSEMEM, but we must mark
them __meminit for SPARSEMEM configurations. This is ok, because then the
calls to alloc_bootmem_node are also avoided.
Compile-tested on:
silly minimal config
defconfig x86_32
defconfig x86_64
defconfig x86_64 -HIBERNATION +MEMORY_HOTPLUG
Signed-off-by: Alexander van Heukelum <heukelum@fastmail.fm>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When we free a page via free_huge_page and we detect that we are in surplus
the page will be returned to the buddy. After this we no longer own the page.
However at the end free_huge_page we clear out our mapping pointer from
page private. Even where the page is not a surplus we free the page to
the hugepage pool, drop the pool locks and then clear page private. In
either case the page may have been reallocated. BAD.
Make sure we clear out page private before we free the page.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Adam Litke <agl@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This reverts commit 1f84260c8ce3b1ce26d4c1d6dedc2f33a3a29c0c, which is
suspected to be the reason for some very occasional and hard-to-trigger
crashes that usually look related to memory allocation (mostly reported
in networking, but since that's generally the most common source of
shortlived allocations - and allocations in interrupt contexts - that in
itself is not a big clue).
See for example
http://bugzilla.kernel.org/show_bug.cgi?id=9973
http://lkml.org/lkml/2008/2/19/278
etc.
One promising suspicion for what the root cause of bug is (which also
explains why it's so hard to trigger in practice) came from Eric
Dumazet:
"I wonder how SLUB_FASTPATH is supposed to work, since it is affected
by a classical ABA problem of lockless algo.
cmpxchg_local(&c->freelist, object, object[c->offset]) can succeed,
while an interrupt came (on this cpu), and several allocations were
done, and one free was performed at the end of this interruption, so
'object' was recycled.
c->freelist can then contain the previous value (object), but
object[c->offset] was changed by IRQ.
We then put back in freelist an already allocated object."
but another reason for the revert is simply that everybody agrees that
this code was the main suspect just by virtue of the pattern of oopses.
Cc: Torsten Kaiser <just.for.lkml@googlemail.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/christoph/vm
* 'slab-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/christoph/vm:
slub: Support 4k kmallocs again to compensate for page allocator slowness
slub: Fallback to kmalloc_large for failing higher order allocs
slub: Determine gfpflags once and not every time a slab is allocated
make slub.c:slab_address() static
slub: kmalloc page allocator pass-through cleanup
slab: avoid double initialization & do initialization in 1 place
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* git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86:
x86: cpa, fix out of date comment
KVM is not seen under X86 config with latest git (32 bit compile)
x86: cpa: ensure page alignment
x86: include proper prototypes for rodata_test
x86: fix gart_iommu_init()
x86: EFI set_memory_x()/set_memory_uc() fixes
x86: make dump_pagetable() static
x86: fix "BUG: sleeping function called from invalid context" in print_vma_addr()
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d_path() is used on a <dentry,vfsmount> pair. Lets use a struct path to
reflect this.
[akpm@linux-foundation.org: fix build in mm/memory.c]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Bryan Wu <bryan.wu@analog.com>
Acked-by: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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seq_path() is always called with a dentry and a vfsmount from a struct path.
Make seq_path() take it directly as an argument.
Signed-off-by: Jan Blunck <jblunck@suse.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Currently we hand off PAGE_SIZEd kmallocs to the page allocator in the
mistaken belief that the page allocator can handle these allocations
effectively. However, measurements indicate a minimum slowdown by the
factor of 8 (and that is only SMP, NUMA is much worse) vs the slub fastpath
which causes regressions in tbench.
Increase the number of kmalloc caches by one so that we again handle 4k
kmallocs directly from slub. 4k page buffering for the page allocator
will be performed by slub like done by slab.
At some point the page allocator fastpath should be fixed. A lot of the kernel
would benefit from a faster ability to allocate a single page. If that is
done then the 4k allocs may again be forwarded to the page allocator and this
patch could be reverted.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Slub already has two ways of allocating an object. One is via its own
logic and the other is via the call to kmalloc_large to hand off object
allocation to the page allocator. kmalloc_large is typically used
for objects >= PAGE_SIZE.
We can use that handoff to avoid failing if a higher order kmalloc slab
allocation cannot be satisfied by the page allocator. If we reach the
out of memory path then simply try a kmalloc_large(). kfree() can
already handle the case of an object that was allocated via the page
allocator and so this will work just fine (apart from object
accounting...).
For any kmalloc slab that already requires higher order allocs (which
makes it impossible to use the page allocator fastpath!)
we just use PAGE_ALLOC_COSTLY_ORDER to get the largest number of
objects in one go from the page allocator slowpath.
On a 4k platform this patch will lead to the following use of higher
order pages for the following kmalloc slabs:
8 ... 1024 order 0
2048 .. 4096 order 3 (4k slab only after the next patch)
We may waste some space if fallback occurs on a 2k slab but we
are always able to fallback to an order 0 alloc.
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Currently we determine the gfp flags to pass to the page allocator
each time a slab is being allocated.
Determine the bits to be set at the time the slab is created. Store
in a new allocflags field and add the flags in allocate_slab().
Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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slab_address() can become static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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This adds a proper function for kmalloc page allocator pass-through. While it
simplifies any code that does slab tracing code a lot, I think it's a
worthwhile cleanup in itself.
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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- alloc_slabmgmt: initialize all slab fields in 1 place
- slab->nodeid was initialized twice: in alloc_slabmgmt
and immediately after it in cache_grow
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
CC: Christoph Lameter <clameter@sgi.com>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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print_vma_addr()
Jiri Kosina reported the following deadlock scenario with
show_unhandled_signals enabled:
[ 68.379022] gnome-settings-[2941] trap int3 ip:3d2c840f34
sp:7fff36f5d100 error:0<3>BUG: sleeping function called from invalid
context at kernel/rwsem.c:21
[ 68.379039] in_atomic():1, irqs_disabled():0
[ 68.379044] no locks held by gnome-settings-/2941.
[ 68.379050] Pid: 2941, comm: gnome-settings- Not tainted 2.6.25-rc1 #30
[ 68.379054]
[ 68.379056] Call Trace:
[ 68.379061] <#DB> [<ffffffff81064883>] ? __debug_show_held_locks+0x13/0x30
[ 68.379109] [<ffffffff81036765>] __might_sleep+0xe5/0x110
[ 68.379123] [<ffffffff812f2240>] down_read+0x20/0x70
[ 68.379137] [<ffffffff8109cdca>] print_vma_addr+0x3a/0x110
[ 68.379152] [<ffffffff8100f435>] do_trap+0xf5/0x170
[ 68.379168] [<ffffffff8100f52b>] do_int3+0x7b/0xe0
[ 68.379180] [<ffffffff812f4a6f>] int3+0x9f/0xd0
[ 68.379203] <<EOE>>
[ 68.379229] in libglib-2.0.so.0.1505.0[3d2c800000+dc000]
and tracked it down to:
commit 03252919b79891063cf99145612360efbdf9500b
Author: Andi Kleen <ak@suse.de>
Date: Wed Jan 30 13:33:18 2008 +0100
x86: print which shared library/executable faulted in segfault etc. messages
the problem is that we call down_read() from an atomic context.
Solve this by returning from print_vma_addr() if the preempt count is
elevated. Update preempt_conditional_sti / preempt_conditional_cli to
unconditionally lift the preempt count even on !CONFIG_PREEMPT.
Reported-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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proc_doulongvec_minmax() calls copy_to_user()/copy_from_user(), so we can't
hold hugetlb_lock over the call. Use a dummy variable to store the sysctl
result, like in hugetlb_sysctl_handler(), then grab the lock to update
nr_overcommit_huge_pages.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Reported-by: Miles Lane <miles.lane@gmail.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fastcall always expands to empty, remove it.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Kosaki Motohito noted that "numactl --interleave=all ..." failed in the
presence of memoryless nodes. This patch attempts to fix that problem.
Some background:
numactl --interleave=all calls set_mempolicy(2) with a fully populated
[out to MAXNUMNODES] nodemask. set_mempolicy() [in do_set_mempolicy()]
calls contextualize_policy() which requires that the nodemask be a
subset of the current task's mems_allowed; else EINVAL will be returned.
A task's mems_allowed will always be a subset of node_states[N_HIGH_MEMORY]
i.e., nodes with memory. So, a fully populated nodemask will be
declared invalid if it includes memoryless nodes.
NOTE: the same thing will occur when running in a cpuset
with restricted mem_allowed--for the same reason:
node mask contains dis-allowed nodes.
mbind(2), on the other hand, just masks off any nodes in the nodemask
that are not included in the caller's mems_allowed.
In each case [mbind() and set_mempolicy()], mpol_check_policy() will
complain [again, resulting in EINVAL] if the nodemask contains any
memoryless nodes. This is somewhat redundant as mpol_new() will remove
memoryless nodes for interleave policy, as will bind_zonelist()--called
by mpol_new() for BIND policy.
Proposed fix:
1) modify contextualize_policy logic to:
a) remember whether the incoming node mask is empty.
b) if not, restrict the nodemask to allowed nodes, as is
currently done in-line for mbind(). This guarantees
that the resulting mask includes only nodes with memory.
NOTE: this is a [benign, IMO] change in behavior for
set_mempolicy(). Dis-allowed nodes will be
silently ignored, rather than returning an error.
c) fold this code into mpol_check_policy(), replace 2 calls to
contextualize_policy() to call mpol_check_policy() directly
and remove contextualize_policy().
2) In existing mpol_check_policy() logic, after "contextualization":
a) MPOL_DEFAULT: require that in coming mask "was_empty"
b) MPOL_{BIND|INTERLEAVE}: require that contextualized nodemask
contains at least one node.
c) add a case for MPOL_PREFERRED: if in coming was not empty
and resulting mask IS empty, user specified invalid nodes.
Return EINVAL.
c) remove the now redundant check for memoryless nodes
3) remove the now redundant masking of policy nodes for interleave
policy from mpol_new().
4) Now that mpol_check_policy() contextualizes the nodemask, remove
the in-line nodes_and() from sys_mbind(). I believe that this
restores mbind() to the behavior before the memoryless-nodes
patch series. E.g., we'll no longer treat an invalid nodemask
with MPOL_PREFERRED as local allocation.
[ Patch history:
v1 -> v2:
- Communicate whether or not incoming node mask was empty to
mpol_check_policy() for better error checking.
- As suggested by David Rientjes, remove the now unused
cpuset_nodes_subset_current_mems_allowed() from cpuset.h
v2 -> v3:
- As suggested by Kosaki Motohito, fold the "contextualization"
of policy nodemask into mpol_check_policy(). Looks a little
cleaner. ]
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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So I spent a while pounding my head against my monitor trying to figure
out the vmsplice() vulnerability - how could a failure to check for
*read* access turn into a root exploit? It turns out that it's a buffer
overflow problem which is made easy by the way get_user_pages() is
coded.
In particular, "len" is a signed int, and it is only checked at the
*end* of a do {} while() loop. So, if it is passed in as zero, the loop
will execute once and decrement len to -1. At that point, the loop will
proceed until the next invalid address is found; in the process, it will
likely overflow the pages array passed in to get_user_pages().
I think that, if get_user_pages() has been asked to grab zero pages,
that's what it should do. Thus this patch; it is, among other things,
enough to block the (already fixed) root exploit and any others which
might be lurking in similar code. I also think that the number of pages
should be unsigned, but changing the prototype of this function probably
requires some more careful review.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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mm_cgroup() is exclusively used to test whether an mm's mem_cgroup pointer
is pointing to a specific cgroup. Instead of returning the pointer, we can
just do the test itself in a new macro:
vm_match_cgroup(mm, cgroup)
returns non-zero if the mm's mem_cgroup points to cgroup. Otherwise it
returns zero.
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Convert special mapping install from nopage to fault.
Because the "vm_file" is NULL for the special mapping, the generic VM
code has messed up "vm_pgoff" thinking that it's an anonymous mapping
and the offset does't matter. For that reason, we need to undo the
vm_pgoff offset that got added into vmf->pgoff.
[ We _really_ should clean that up - either by making this whole special
mapping code just use a real file entry rather than that ugly array of
"struct page" pointers, or by just making the VM code realize that
even if vm_file is NULL it may not be a regular anonymous mmap.
- Linus ]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Background: I've implemented 1K/2K page tables for s390. These sub-page
page tables are required to properly support the s390 virtualization
instruction with KVM. The SIE instruction requires that the page tables
have 256 page table entries (pte) followed by 256 page status table entries
(pgste). The pgstes are only required if the process is using the SIE
instruction. The pgstes are updated by the hardware and by the hypervisor
for a number of reasons, one of them is dirty and reference bit tracking.
To avoid wasting memory the standard pte table allocation should return
1K/2K (31/64 bit) and 2K/4K if the process is using SIE.
Problem: Page size on s390 is 4K, page table size is 1K or 2K. That means
the s390 version for pte_alloc_one cannot return a pointer to a struct
page. Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one
cannot return a pointer to a pte either, since that would require more than
32 bit for the return value of pte_alloc_one (and the pte * would not be
accessible since its not kmapped).
Solution: The only solution I found to this dilemma is a new typedef: a
pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced with a
later patch. For everybody else it will be a (struct page *). The
additional problem with the initialization of the ptl lock and the
NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and
a destructor pgtable_page_dtor. The page table allocation and free
functions need to call these two whenever a page table page is allocated or
freed. pmd_populate will get a pgtable_t instead of a struct page pointer.
To get the pgtable_t back from a pmd entry that has been installed with
pmd_populate a new function pmd_pgtable is added. It replaces the pmd_page
call in free_pte_range and apply_to_pte_range.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Documentation/SubmitCheckist, please.
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Add .show_options super operation to tmpfs.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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do_generic_mapping_read was used by gfs2 for internals reads, but this use
of the interface was rather suboptimal (as was the whole interface) and has
been replaced by an internal helper now. This patch kills
do_generic_mapping_read and surrounding damage in preparation of additional
cleanups for the buffered read path.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Convert variables containing page indexes to pgoff_t.
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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When I replaced hugetlb_dynamic_pool with nr_overcommit_hugepages I used
proc_doulongvec_minmax() directly. However, hugetlb.c's locking rules
require that all counter modifications occur under the hugetlb_lock. Add a
callback into the hugetlb code similar to the one for nr_hugepages. Grab
the lock around the manipulation of nr_overcommit_hugepages in
proc_doulongvec_minmax().
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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fix checkpatch --file mm/slub.c errors and warnings.
$ q-code-quality-compare
errors lines of code errors/KLOC
mm/slub.c [before] 22 4204 5.2
mm/slub.c [after] 0 4210 0
no code changed:
text data bss dec hex filename
22195 8634 136 30965 78f5 slub.o.before
22195 8634 136 30965 78f5 slub.o.after
md5:
93cdfbec2d6450622163c590e1064358 slub.o.before.asm
93cdfbec2d6450622163c590e1064358 slub.o.after.asm
[clameter: rediffed against Pekka's cleanup patch, omitted
moves of the name of a function to the start of line]
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Slub can use the non-atomic version to unlock because other flags will not
get modified with the lock held.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The statistics provided here allow the monitoring of allocator behavior but
at the cost of some (minimal) loss of performance. Counters are placed in
SLUB's per cpu data structure. The per cpu structure may be extended by the
statistics to grow larger than one cacheline which will increase the cache
footprint of SLUB.
There is a compile option to enable/disable the inclusion of the runtime
statistics and its off by default.
The slabinfo tool is enhanced to support these statistics via two options:
-D Switches the line of information displayed for a slab from size
mode to activity mode.
-A Sorts the slabs displayed by activity. This allows the display of
the slabs most important to the performance of a certain load.
-r Report option will report detailed statistics on
Example (tbench load):
slabinfo -AD ->Shows the most active slabs
Name Objects Alloc Free %Fast
skbuff_fclone_cache 33 111953835 111953835 99 99
:0000192 2666 5283688 5281047 99 99
:0001024 849 5247230 5246389 83 83
vm_area_struct 1349 119642 118355 91 22
:0004096 15 66753 66751 98 98
:0000064 2067 25297 23383 98 78
dentry 10259 28635 18464 91 45
:0000080 11004 18950 8089 98 98
:0000096 1703 12358 10784 99 98
:0000128 762 10582 9875 94 18
:0000512 184 9807 9647 95 81
:0002048 479 9669 9195 83 65
anon_vma 777 9461 9002 99 71
kmalloc-8 6492 9981 5624 99 97
:0000768 258 7174 6931 58 15
So the skbuff_fclone_cache is of highest importance for the tbench load.
Pretty high load on the 192 sized slab. Look for the aliases
slabinfo -a | grep 000192
:0000192 <- xfs_btree_cur filp kmalloc-192 uid_cache tw_sock_TCP
request_sock_TCPv6 tw_sock_TCPv6 skbuff_head_cache xfs_ili
Likely skbuff_head_cache.
Looking into the statistics of the skbuff_fclone_cache is possible through
slabinfo skbuff_fclone_cache ->-r option implied if cache name is mentioned
.... Usual output ...
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 111953360 111946981 99 99
Slowpath 1044 7423 0 0
Page Alloc 272 264 0 0
Add partial 25 325 0 0
Remove partial 86 264 0 0
RemoteObj/SlabFrozen 350 4832 0 0
Total 111954404 111954404
Flushes 49 Refill 0
Deactivate Full=325(92%) Empty=0(0%) ToHead=24(6%) ToTail=1(0%)
Looks good because the fastpath is overwhelmingly taken.
skbuff_head_cache:
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 5297262 5259882 99 99
Slowpath 4477 39586 0 0
Page Alloc 937 824 0 0
Add partial 0 2515 0 0
Remove partial 1691 824 0 0
RemoteObj/SlabFrozen 2621 9684 0 0
Total 5301739 5299468
Deactivate Full=2620(100%) Empty=0(0%) ToHead=0(0%) ToTail=0(0%)
Descriptions of the output:
Total: The total number of allocation and frees that occurred for a
slab
Fastpath: The number of allocations/frees that used the fastpath.
Slowpath: Other allocations
Page Alloc: Number of calls to the page allocator as a result of slowpath
processing
Add Partial: Number of slabs added to the partial list through free or
alloc (occurs during cpuslab flushes)
Remove Partial: Number of slabs removed from the partial list as a result of
allocations retrieving a partial slab or by a free freeing
the last object of a slab.
RemoteObj/Froz: How many times were remotely freed object encountered when a
slab was about to be deactivated. Frozen: How many times was
free able to skip list processing because the slab was in use
as the cpuslab of another processor.
Flushes: Number of times the cpuslab was flushed on request
(kmem_cache_shrink, may result from races in __slab_alloc)
Refill: Number of times we were able to refill the cpuslab from
remotely freed objects for the same slab.
Deactivate: Statistics how slabs were deactivated. Shows how they were
put onto the partial list.
In general fastpath is very good. Slowpath without partial list processing is
also desirable. Any touching of partial list uses node specific locks which
may potentially cause list lock contention.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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Provide an alternate implementation of the SLUB fast paths for alloc
and free using cmpxchg_local. The cmpxchg_local fast path is selected
for arches that have CONFIG_FAST_CMPXCHG_LOCAL set. An arch should only
set CONFIG_FAST_CMPXCHG_LOCAL if the cmpxchg_local is faster than an
interrupt enable/disable sequence. This is known to be true for both
x86 platforms so set FAST_CMPXCHG_LOCAL for both arches.
Currently another requirement for the fastpath is that the kernel is
compiled without preemption. The restriction will go away with the
introduction of a new per cpu allocator and new per cpu operations.
The advantages of a cmpxchg_local based fast path are:
1. Potentially lower cycle count (30%-60% faster)
2. There is no need to disable and enable interrupts on the fast path.
Currently interrupts have to be disabled and enabled on every
slab operation. This is likely avoiding a significant percentage
of interrupt off / on sequences in the kernel.
3. The disposal of freed slabs can occur with interrupts enabled.
The alternate path is realized using #ifdef's. Several attempts to do the
same with macros and inline functions resulted in a mess (in particular due
to the strange way that local_interrupt_save() handles its argument and due
to the need to define macros/functions that sometimes disable interrupts
and sometimes do something else).
[clameter: Stripped preempt bits and disabled fastpath if preempt is enabled]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Reviewed-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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We use a NULL pointer on freelists to signal that there are no more objects.
However the NULL pointers of all slabs match in contrast to the pointers to
the real objects which are in different ranges for different slab pages.
Change the end pointer to be a pointer to the first object and set bit 0.
Every slab will then have a different end pointer. This is necessary to ensure
that end markers can be matched to the source slab during cmpxchg_local.
Bring back the use of the mapping field by SLUB since we would otherwise have
to call a relatively expensive function page_address() in __slab_alloc(). Use
of the mapping field allows avoiding a call to page_address() in various other
functions as well.
There is no need to change the page_mapping() function since bit 0 is set on
the mapping as also for anonymous pages. page_mapping(slab_page) will
therefore still return NULL although the mapping field is overloaded.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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gcc 4.2 spits out an annoying warning if one casts a const void *
pointer to a void * pointer. No warning is generated if the
conversion is done through an assignment.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
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This patchset adds a flags variable to reserve_bootmem() and uses the
BOOTMEM_EXCLUSIVE flag in crashkernel reservation code to detect collisions
between crashkernel area and already used memory.
This patch:
Change the reserve_bootmem() function to accept a new flag BOOTMEM_EXCLUSIVE.
If that flag is set, the function returns with -EBUSY if the memory already
has been reserved in the past. This is to avoid conflicts.
Because that code runs before SMP initialisation, there's no race condition
inside reserve_bootmem_core().
[akpm@linux-foundation.org: coding-style fixes]
[akpm@linux-foundation.org: fix powerpc build]
Signed-off-by: Bernhard Walle <bwalle@suse.de>
Cc: <linux-arch@vger.kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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