I have never seen a use of SLAB_DEBUG_INITIAL. It is only supported by
SLAB.
I think its purpose was to have a callback after an object has been freed
to verify that the state is the constructor state again? The callback is
performed before each freeing of an object.
I would think that it is much easier to check the object state manually
before the free. That also places the check near the code object
manipulation of the object.
Also the SLAB_DEBUG_INITIAL callback is only performed if the kernel was
compiled with SLAB debugging on. If there would be code in a constructor
handling SLAB_DEBUG_INITIAL then it would have to be conditional on
SLAB_DEBUG otherwise it would just be dead code. But there is no such code
in the kernel. I think SLUB_DEBUG_INITIAL is too problematic to make real
use of, difficult to understand and there are easier ways to accomplish the
same effect (i.e. add debug code before kfree).
There is a related flag SLAB_CTOR_VERIFY that is frequently checked to be
clear in fs inode caches. Remove the pointless checks (they would even be
pointless without removeal of SLAB_DEBUG_INITIAL) from the fs constructors.
This is the last slab flag that SLUB did not support. Remove the check for
unimplemented flags from SLUB.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Remove the hugetlbfs specific hacks in toplevel get_unmapped_area() now that
all archs and hugetlbfs itself do the right thing for both cases.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Acked-by: William Irwin <bill.irwin@oracle.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Cc: "David S. Miller" <davem@davemloft.net>
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>
generic arch_get_unmapped_area() now handles MAP_FIXED. Now that all
implementations have been fixed, change the toplevel get_unmapped_area() to
call into arch or drivers for the MAP_FIXED case.
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk+kernel@arm.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Grant Grundler <grundler@parisc-linux.org>
Cc: Matthew Wilcox <willy@debian.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: William Irwin <bill.irwin@oracle.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>
Fixes a deadlock in the OOM killer for allocations that are not
__GFP_HARDWALL.
Before the OOM killer checks for the allocation constraint, it takes
callback_mutex.
constrained_alloc() iterates through each zone in the allocation zonelist
and calls cpuset_zone_allowed_softwall() to determine whether an allocation
for gfp_mask is possible. If a zone's node is not in the OOM-triggering
task's mems_allowed, it is not exiting, and we did not fail on a
__GFP_HARDWALL allocation, cpuset_zone_allowed_softwall() attempts to take
callback_mutex to check the nearest exclusive ancestor of current's cpuset.
This results in deadlock.
We now take callback_mutex after iterating through the zonelist since we
don't need it yet.
Cc: Andi Kleen <ak@suse.de>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: Martin J. Bligh <mbligh@mbligh.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current panic_on_oom may not work if there is a process using
cpusets/mempolicy, because other nodes' memory may remain. But some people
want failover by panic ASAP even if they are used. This patch makes new
setting for its request.
This is tested on my ia64 box which has 3 nodes.
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Ethan Solomita <solo@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently failslab injects failures into ____cache_alloc(). But with enabling
CONFIG_NUMA it's not enough to let actual slab allocator functions (kmalloc,
kmem_cache_alloc, ...) return NULL.
This patch moves fault injection hook inside of __cache_alloc() and
__cache_alloc_node(). These are lower call path than ____cache_alloc() and
enable to inject faulures to slab allocators with CONFIG_NUMA.
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch was recently posted to lkml and acked by Pekka.
The flag SLAB_MUST_HWCACHE_ALIGN is
1. Never checked by SLAB at all.
2. A duplicate of SLAB_HWCACHE_ALIGN for SLUB
3. Fulfills the role of SLAB_HWCACHE_ALIGN for SLOB.
The only remaining use is in sparc64 and ppc64 and their use there
reflects some earlier role that the slab flag once may have had. If
its specified then SLAB_HWCACHE_ALIGN is also specified.
The flag is confusing, inconsistent and has no purpose.
Remove it.
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Avoid down_write of the mmap_sem in madvise when we can help it.
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
On x86_64 this cuts allocation overhead for page table pages down to a
fraction (kernel compile / editing load. TSC based measurement of times spend
in each function):
no quicklist
pte_alloc 1569048 4.3s(401ns/2.7us/179.7us)
pmd_alloc 780988 2.1s(337ns/2.7us/86.1us)
pud_alloc 780072 2.2s(424ns/2.8us/300.6us)
pgd_alloc 260022 1s(920ns/4us/263.1us)
quicklist:
pte_alloc 452436 573.4ms(8ns/1.3us/121.1us)
pmd_alloc 196204 174.5ms(7ns/889ns/46.1us)
pud_alloc 195688 172.4ms(7ns/881ns/151.3us)
pgd_alloc 65228 9.8ms(8ns/150ns/6.1us)
pgd allocations are the most complex and there we see the most dramatic
improvement (may be we can cut down the amount of pgds cached somewhat?). But
even the pte allocations still see a doubling of performance.
1. Proven code from the IA64 arch.
The method used here has been fine tuned for years and
is NUMA aware. It is based on the knowledge that accesses
to page table pages are sparse in nature. Taking a page
off the freelists instead of allocating a zeroed pages
allows a reduction of number of cachelines touched
in addition to getting rid of the slab overhead. So
performance improves. This is particularly useful if pgds
contain standard mappings. We can save on the teardown
and setup of such a page if we have some on the quicklists.
This includes avoiding lists operations that are otherwise
necessary on alloc and free to track pgds.
2. Light weight alternative to use slab to manage page size pages
Slab overhead is significant and even page allocator use
is pretty heavy weight. The use of a per cpu quicklist
means that we touch only two cachelines for an allocation.
There is no need to access the page_struct (unless arch code
needs to fiddle around with it). So the fast past just
means bringing in one cacheline at the beginning of the
page. That same cacheline may then be used to store the
page table entry. Or a second cacheline may be used
if the page table entry is not in the first cacheline of
the page. The current code will zero the page which means
touching 32 cachelines (assuming 128 byte). We get down
from 32 to 2 cachelines in the fast path.
3. x86_64 gets lightweight page table page management.
This will allow x86_64 arch code to faster repopulate pgds
and other page table entries. The list operations for pgds
are reduced in the same way as for i386 to the point where
a pgd is allocated from the page allocator and when it is
freed back to the page allocator. A pgd can pass through
the quicklists without having to be reinitialized.
64 Consolidation of code from multiple arches
So far arches have their own implementation of quicklist
management. This patch moves that feature into the core allowing
an easier maintenance and consistent management of quicklists.
Page table pages have the characteristics that they are typically zero or in a
known state when they are freed. This is usually the exactly same state as
needed after allocation. So it makes sense to build a list of freed page
table pages and then consume the pages already in use first. Those pages have
already been initialized correctly (thus no need to zero them) and are likely
already cached in such a way that the MMU can use them most effectively. Page
table pages are used in a sparse way so zeroing them on allocation is not too
useful.
Such an implementation already exits for ia64. Howver, that implementation
did not support constructors and destructors as needed by i386 / x86_64. It
also only supported a single quicklist. The implementation here has
constructor and destructor support as well as the ability for an arch to
specify how many quicklists are needed.
Quicklists are defined by an arch defining CONFIG_QUICKLIST. If more than one
quicklist is necessary then we can define NR_QUICK for additional lists. F.e.
i386 needs two and thus has
config NR_QUICK
int
default 2
If an arch has requested quicklist support then pages can be allocated
from the quicklist (or from the page allocator if the quicklist is
empty) via:
quicklist_alloc(<quicklist-nr>, <gfpflags>, <constructor>)
Page table pages can be freed using:
quicklist_free(<quicklist-nr>, <destructor>, <page>)
Pages must have a definite state after allocation and before
they are freed. If no constructor is specified then pages
will be zeroed on allocation and must be zeroed before they are
freed.
If a constructor is used then the constructor will establish
a definite page state. F.e. the i386 and x86_64 pgd constructors
establish certain mappings.
Constructors and destructors can also be used to track the pages.
i386 and x86_64 use a list of pgds in order to be able to dynamically
update standard mappings.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make sure that the check function really only check things and do not perform
activities. Extract the tracing and object seeding out of the two check
functions and place them into slab_alloc and slab_free
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
At kmem_cache_shrink check if we have any empty slabs on the partial
if so then remove them.
Also--as an anti-fragmentation measure--sort the partial slabs so that
the most fully allocated ones come first and the least allocated last.
The next allocations may fill up the nearly full slabs. Having the
least allocated slabs last gives them the maximum chance that their
remaining objects may be freed. Thus we can hopefully minimize the
partial slabs.
I think this is the best one can do in terms antifragmentation
measures. Real defragmentation (meaning moving objects out of slabs with
the least free objects to those that are almost full) can be implemted
by reverse scanning through the list produced here but that would mean
that we need to provide a callback at slab cache creation that allows
the deletion or moving of an object. This will involve slab API
changes, so defer for now.
Cc: Mel Gorman <mel@skynet.ie>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch enables listing the callers who allocated or freed objects in a
cache.
For example to list the allocators for kmalloc-128 do
cat /sys/slab/kmalloc-128/alloc_calls
7 sn_io_slot_fixup+0x40/0x700
7 sn_io_slot_fixup+0x80/0x700
9 sn_bus_fixup+0xe0/0x380
6 param_sysfs_setup+0xf0/0x280
276 percpu_populate+0xf0/0x1a0
19 __register_chrdev_region+0x30/0x360
8 expand_files+0x2e0/0x6e0
1 sys_epoll_create+0x60/0x200
1 __mounts_open+0x140/0x2c0
65 kmem_alloc+0x110/0x280
3 alloc_disk_node+0xe0/0x200
33 as_get_io_context+0x90/0x280
74 kobject_kset_add_dir+0x40/0x140
12 pci_create_bus+0x2a0/0x5c0
1 acpi_ev_create_gpe_block+0x120/0x9e0
41 con_insert_unipair+0x100/0x1c0
1 uart_open+0x1c0/0xba0
1 dma_pool_create+0xe0/0x340
2 neigh_table_init_no_netlink+0x260/0x4c0
6 neigh_parms_alloc+0x30/0x200
1 netlink_kernel_create+0x130/0x320
5 fz_hash_alloc+0x50/0xe0
2 sn_common_hubdev_init+0xd0/0x6e0
28 kernel_param_sysfs_setup+0x30/0x180
72 process_zones+0x70/0x2e0
cat /sys/slab/kmalloc-128/free_calls
558 <not-available>
3 sn_io_slot_fixup+0x600/0x700
84 free_fdtable_rcu+0x120/0x260
2 seq_release+0x40/0x60
6 kmem_free+0x70/0xc0
24 free_as_io_context+0x20/0x200
1 acpi_get_object_info+0x3a0/0x3e0
1 acpi_add_single_object+0xcf0/0x1e40
2 con_release_unimap+0x80/0x140
1 free+0x20/0x40
SLAB_STORE_USER must be enabled for a slab cache by either booting with
"slab_debug" or enabling user tracking specifically for the slab of interest.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We leave a mininum of partial slabs on nodes when we search for
partial slabs on other node. Define a constant for that value.
Then modify slub to keep MIN_PARTIAL slabs around.
This avoids bad situations where a function frees the last object
in a slab (which results in the page being returned to the page
allocator) only to then allocate one again (which requires getting
a page back from the page allocator if the partial list was empty).
Keeping a couple of slabs on the partial list reduces overhead.
Empty slabs are added to the end of the partial list to insure that
partially allocated slabs are consumed first (defragmentation).
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This enables validation of slab. Validation means that all objects are
checked to see if there are redzone violations, if padding has been
overwritten or any pointers have been corrupted. Also checks the consistency
of slab counters.
Validation enables the detection of metadata corruption without the kernel
having to execute code that actually uses (allocs/frees) and object. It
allows one to make sure that the slab metainformation and the guard values
around an object have not been compromised.
A single slabcache can be checked by writing a 1 to the "validate" file.
i.e.
echo 1 >/sys/slab/kmalloc-128/validate
or use the slabinfo tool to check all slabs
slabinfo -v
Error messages will show up in the syslog.
Note that validation can only reach slabs that are on a list. This means that
we are usually restricted to partial slabs and active slabs unless
SLAB_STORE_USER is active which will build a full slab list and allows
validation of slabs that are fully in use. Booting with "slub_debug" set will
enable SLAB_STORE_USER and then full diagnostic are available.
Note that we attempt to push cpu slabs back to the lists when we start the
check. If the cpu slab is reactivated before we get to it (another processor
grabs it before we get to it) then it cannot be checked.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If slab tracking is on then build a list of full slabs so that we can verify
the integrity of all slabs and are also able to built list of alloc/free
callers.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Object tracking did not work the right way for several call chains. Fix this up
by adding a new parameter to slub_alloc and slub_free that specifies the
caller address explicitly.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The patch adds PageTail(page) and PageHead(page) to check if a page is the
head or the tail of a compound page. This is done by masking the two bits
describing the state of a compound page and then comparing them. So one
comparision and a branch instead of two bit checks and two branches.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If we add a new flag so that we can distinguish between the first page and the
tail pages then we can avoid to use page->private in the first page.
page->private == page for the first page, so there is no real information in
there.
Freeing up page->private makes the use of compound pages more transparent.
They become more usable like real pages. Right now we have to be careful f.e.
if we are going beyond PAGE_SIZE allocations in the slab on i386 because we
can then no longer use the private field. This is one of the issues that
cause us not to support debugging for page size slabs in SLAB.
Having page->private available for SLUB would allow more meta information in
the page struct. I can probably avoid the 16 bit ints that I have in there
right now.
Also if page->private is available then a compound page may be equipped with
buffer heads. This may free up the way for filesystems to support larger
blocks than page size.
We add PageTail as an alias of PageReclaim. Compound pages cannot currently
be reclaimed. Because of the alias one needs to check PageCompound first.
The RFC for the this approach was discussed at
http://marc.info/?t=117574302800001&r=1&w=2
[nacc@us.ibm.com: fix hugetlbfs]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Makes SLUB behave like SLAB in this area to avoid issues....
Throw a stack dump to alert people.
At some point the behavior should be switched back. NULL is no memory as
far as I can tell and if the use asked for 0 bytes then he need to get no
memory.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Structures may contain u64 items on 32 bit platforms that are only able to
address 64 bit items on 64 bit boundaries. Change the mininum alignment of
slabs to conform to those expectations.
ARCH_KMALLOC_MINALIGN must be changed for good since a variety of structure
are mixed in the general slabs.
ARCH_SLAB_MINALIGN is changed because currently there is no consistent
specification of object alignment. We may have that in the future when the
KMEM_CACHE and related macros are used to generate slabs. These pass the
alignment of the structure generated by the compiler to the slab.
With KMEM_CACHE etc we could align structures that do not contain 64
bit values to 32 bit boundaries potentially saving some memory.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is a new slab allocator which was motivated by the complexity of the
existing code in mm/slab.c. It attempts to address a variety of concerns
with the existing implementation.
A. Management of object queues
A particular concern was the complex management of the numerous object
queues in SLAB. SLUB has no such queues. Instead we dedicate a slab for
each allocating CPU and use objects from a slab directly instead of
queueing them up.
B. Storage overhead of object queues
SLAB Object queues exist per node, per CPU. The alien cache queue even
has a queue array that contain a queue for each processor on each
node. For very large systems the number of queues and the number of
objects that may be caught in those queues grows exponentially. On our
systems with 1k nodes / processors we have several gigabytes just tied up
for storing references to objects for those queues This does not include
the objects that could be on those queues. One fears that the whole
memory of the machine could one day be consumed by those queues.
C. SLAB meta data overhead
SLAB has overhead at the beginning of each slab. This means that data
cannot be naturally aligned at the beginning of a slab block. SLUB keeps
all meta data in the corresponding page_struct. Objects can be naturally
aligned in the slab. F.e. a 128 byte object will be aligned at 128 byte
boundaries and can fit tightly into a 4k page with no bytes left over.
SLAB cannot do this.
D. SLAB has a complex cache reaper
SLUB does not need a cache reaper for UP systems. On SMP systems
the per CPU slab may be pushed back into partial list but that
operation is simple and does not require an iteration over a list
of objects. SLAB expires per CPU, shared and alien object queues
during cache reaping which may cause strange hold offs.
E. SLAB has complex NUMA policy layer support
SLUB pushes NUMA policy handling into the page allocator. This means that
allocation is coarser (SLUB does interleave on a page level) but that
situation was also present before 2.6.13. SLABs application of
policies to individual slab objects allocated in SLAB is
certainly a performance concern due to the frequent references to
memory policies which may lead a sequence of objects to come from
one node after another. SLUB will get a slab full of objects
from one node and then will switch to the next.
F. Reduction of the size of partial slab lists
SLAB has per node partial lists. This means that over time a large
number of partial slabs may accumulate on those lists. These can
only be reused if allocator occur on specific nodes. SLUB has a global
pool of partial slabs and will consume slabs from that pool to
decrease fragmentation.
G. Tunables
SLAB has sophisticated tuning abilities for each slab cache. One can
manipulate the queue sizes in detail. However, filling the queues still
requires the uses of the spin lock to check out slabs. SLUB has a global
parameter (min_slab_order) for tuning. Increasing the minimum slab
order can decrease the locking overhead. The bigger the slab order the
less motions of pages between per CPU and partial lists occur and the
better SLUB will be scaling.
G. Slab merging
We often have slab caches with similar parameters. SLUB detects those
on boot up and merges them into the corresponding general caches. This
leads to more effective memory use. About 50% of all caches can
be eliminated through slab merging. This will also decrease
slab fragmentation because partial allocated slabs can be filled
up again. Slab merging can be switched off by specifying
slub_nomerge on boot up.
Note that merging can expose heretofore unknown bugs in the kernel
because corrupted objects may now be placed differently and corrupt
differing neighboring objects. Enable sanity checks to find those.
H. Diagnostics
The current slab diagnostics are difficult to use and require a
recompilation of the kernel. SLUB contains debugging code that
is always available (but is kept out of the hot code paths).
SLUB diagnostics can be enabled via the "slab_debug" option.
Parameters can be specified to select a single or a group of
slab caches for diagnostics. This means that the system is running
with the usual performance and it is much more likely that
race conditions can be reproduced.
I. Resiliency
If basic sanity checks are on then SLUB is capable of detecting
common error conditions and recover as best as possible to allow the
system to continue.
J. Tracing
Tracing can be enabled via the slab_debug=T,<slabcache> option
during boot. SLUB will then protocol all actions on that slabcache
and dump the object contents on free.
K. On demand DMA cache creation.
Generally DMA caches are not needed. If a kmalloc is used with
__GFP_DMA then just create this single slabcache that is needed.
For systems that have no ZONE_DMA requirement the support is
completely eliminated.
L. Performance increase
Some benchmarks have shown speed improvements on kernbench in the
range of 5-10%. The locking overhead of slub is based on the
underlying base allocation size. If we can reliably allocate
larger order pages then it is possible to increase slub
performance much further. The anti-fragmentation patches may
enable further performance increases.
Tested on:
i386 UP + SMP, x86_64 UP + SMP + NUMA emulation, IA64 NUMA + Simulator
SLUB Boot options
slub_nomerge Disable merging of slabs
slub_min_order=x Require a minimum order for slab caches. This
increases the managed chunk size and therefore
reduces meta data and locking overhead.
slub_min_objects=x Mininum objects per slab. Default is 8.
slub_max_order=x Avoid generating slabs larger than order specified.
slub_debug Enable all diagnostics for all caches
slub_debug=<options> Enable selective options for all caches
slub_debug=<o>,<cache> Enable selective options for a certain set of
caches
Available Debug options
F Double Free checking, sanity and resiliency
R Red zoning
P Object / padding poisoning
U Track last free / alloc
T Trace all allocs / frees (only use for individual slabs).
To use SLUB: Apply this patch and then select SLUB as the default slab
allocator.
[hugh@veritas.com: fix an oops-causing locking error]
[akpm@linux-foundation.org: various stupid cleanups and small fixes]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It is only ever used prior to free_initmem().
(It will cause a warning when we run the section checking, but that's a
false-positive and it simply changes the source of an existing warning, which
is also a false-positive)
Cc: Christoph Lameter <clameter@engr.sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The sysctl handler for min_free_kbytes calls setup_per_zone_pages_min() on
read or write. This function iterates through every zone and calls
spin_lock_irqsave() on the zone LRU lock. When reading min_free_kbytes,
this is a total waste of time that disables interrupts on the local
processor. It might even be noticable machines with large numbers of zones
if a process started constantly reading min_free_kbytes.
This patch only calls setup_per_zone_pages_min() only on write. Tested on
an x86 laptop and it did the right thing.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Some NUMA machines have a big MAX_NUMNODES (possibly 1024), but fewer
possible nodes. This patch dynamically sizes the 'struct kmem_cache' to
allocate only needed space.
I moved nodelists[] field at the end of struct kmem_cache, and use the
following computation in kmem_cache_init()
cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) +
nr_node_ids * sizeof(struct kmem_list3 *);
On my two nodes x86_64 machine, kmem_cache.obj_size is now 192 instead of 704
(This is because on x86_64, MAX_NUMNODES is 64)
On bigger NUMA setups, this might reduce the gfporder of "cache_cache"
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can avoid allocating empty shared caches and avoid unecessary check of
cache->limit. We save some memory. We avoid bringing into CPU cache
unecessary cache lines.
All accesses to l3->shared are already checking NULL pointers so this patch is
safe.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The existing comment in mm/slab.c is *perfect*, so I reproduce it :
/*
* CPU bound tasks (e.g. network routing) can exhibit cpu bound
* allocation behaviour: Most allocs on one cpu, most free operations
* on another cpu. For these cases, an efficient object passing between
* cpus is necessary. This is provided by a shared array. The array
* replaces Bonwick's magazine layer.
* On uniprocessor, it's functionally equivalent (but less efficient)
* to a larger limit. Thus disabled by default.
*/
As most shiped linux kernels are now compiled with CONFIG_SMP, there is no way
a preprocessor #if can detect if the machine is UP or SMP. Better to use
num_possible_cpus().
This means on UP we allocate a 'size=0 shared array', to be more efficient.
Another patch can later avoid the allocations of 'empty shared arrays', to
save some memory.
Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename file_ra_state.prev_page to prev_index and file_ra_state.offset to
prev_offset. Also update of prev_index in do_generic_mapping_read() is now
moved close to the update of prev_offset.
[wfg@mail.ustc.edu.cn: fix it]
Signed-off-by: Jan Kara <jack@suse.cz>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: WU Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: Fengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce ra.offset and store in it an offset where the previous read
ended. This way we can detect whether reads are really sequential (and
thus we should not mark the page as accessed repeatedly) or whether they
are random and just happen to be in the same page (and the page should
really be marked accessed again).
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: WU Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce a macro for suppressing gcc from generating a warning about a
probable uninitialized state of a variable.
Example:
- spinlock_t *ptl;
+ spinlock_t *uninitialized_var(ptl);
Not a happy solution, but those warnings are obnoxious.
- Using the usual pointlessly-set-it-to-zero approach wastes several
bytes of text.
- Using a macro means we can (hopefully) do something else if gcc changes
cause the `x = x' hack to stop working
- Using a macro means that people who are worried about hiding true bugs
can easily turn it off.
Signed-off-by: Borislav Petkov <bbpetkov@yahoo.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Identical block is duplicated twice: contrary to the comment, we have been
re-reading the page *twice* in filemap_nopage rather than once.
If any retry logic or anything is needed, it belongs in lower levels anyway.
Only retry once. Linus agrees.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Generally we work under the assumption that memory the mem_map array is
contigious and valid out to MAX_ORDER_NR_PAGES block of pages, ie. that if we
have validated any page within this MAX_ORDER_NR_PAGES block we need not check
any other. This is not true when CONFIG_HOLES_IN_ZONE is set and we must
check each and every reference we make from a pfn.
Add a pfn_valid_within() helper which should be used when scanning pages
within a MAX_ORDER_NR_PAGES block when we have already checked the validility
of the block normally with pfn_valid(). This can then be optimised away when
we do not have holes within a MAX_ORDER_NR_PAGES block of pages.
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Bob Picco <bob.picco@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If the badness of a process is zero then oom_adj>0 has no effect. This
patch makes sure that the oom_adj shift actually increases badness points
appropriately.
Signed-off-by: Joshua N. Pritikin <jpritikin@pobox.com>
Cc: Andrea Arcangeli <andrea@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Ensure pages are uptodate after returning from read_cache_page, which allows
us to cut out most of the filesystem-internal PageUptodate calls.
I didn't have a great look down the call chains, but this appears to fixes 7
possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in
ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in
block2mtd. All depending on whether the filler is async and/or can return
with a !uptodate page.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If slab->inuse is corrupted, cache_alloc_refill can enter an infinite
loop as detailed by Michael Richardson in the following post:
<http://lkml.org/lkml/2007/2/16/292>. This adds a BUG_ON to catch
those cases.
Cc: Michael Richardson <mcr@sandelman.ca>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Minimum gcc version is 3.2 now. However, with likely profiling, even
modern gcc versions cannot always eliminate the call.
Replace the placeholder functions with the more conventional empty static
inlines, which should be optimal for everyone.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can use the global ZVC counters to establish the exact size of the LRU
and the free pages. This allows a more accurate determination of the dirty
ratio.
This patch will fix the broken ratio calculations if large amounts of
memory are allocated to huge pags or other consumers that do not put the
pages on to the LRU.
Notes:
- I did not add NR_SLAB_RECLAIMABLE to the calculation of the
dirtyable pages. Those may be reclaimable but they are at this
point not dirtyable. If NR_SLAB_RECLAIMABLE would be considered
then a huge number of reclaimable pages would stop writeback
from occurring.
- This patch used to be in mm as the last one in a series of patches.
It was removed when Linus updated the treatment of highmem because
there was a conflict. I updated the patch to follow Linus' approach.
This patch is neede to fulfill the claims made in the beginning of the
patchset that is now in Linus' tree.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The nr_cpu_ids value is currently only calculated in smp_init. However, it
may be needed before (SLUB needs it on kmem_cache_init!) and other kernel
components may also want to allocate dynamically sized per cpu array before
smp_init. So move the determination of possible cpus into sched_init()
where we already loop over all possible cpus early in boot.
Also initialize both nr_node_ids and nr_cpu_ids with the highest value they
could take. If we have accidental users before these values are determined
then the current valud of 0 may cause too small per cpu and per node arrays
to be allocated. If it is set to the maximum possible then we only waste
some memory for early boot users.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a new mm function apply_to_page_range() which applies a given function to
every pte in a given virtual address range in a given mm structure. This is a
generic alternative to cut-and-pasting the Linux idiomatic pagetable walking
code in every place that a sequence of PTEs must be accessed.
Although this interface is intended to be useful in a wide range of
situations, it is currently used specifically by several Xen subsystems, for
example: to ensure that pagetables have been allocated for a virtual address
range, and to construct batched special pagetable update requests to map I/O
memory (in ioremap()).
[akpm@linux-foundation.org: fix warning, unpleasantly]
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Matt Mackall <mpm@waste.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This introduce krealloc() that reallocates memory while keeping the contents
unchanged. The allocator avoids reallocation if the new size fits the
currently used cache. I also added a simple non-optimized version for
mm/slob.c for compatibility.
[akpm@linux-foundation.org: fix warnings]
Acked-by: Josef Sipek <jsipek@fsl.cs.sunysb.edu>
Acked-by: Matt Mackall <mpm@selenic.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Set use_alien_caches to 0 on non NUMA platforms. And avoid calling the
cache_free_alien() when use_alien_caches is not set. This will avoid the
cache miss that happens while dereferencing slabp to get nodeid.
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space. These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.
Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.
This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings. Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.
[ Zach - vmi.c will need some attention after this patch. It wasn't
immediately obvious to me what needs to be done. ]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
Add hooks to allow a paravirt implementation to track the lifetime of
an mm. Paravirtualization requires three hooks, but only two are
needed in common code. They are:
arch_dup_mmap, which is called when a new mmap is created at fork
arch_exit_mmap, which is called when the last process reference to an
mm is dropped, which typically happens on exit and exec.
The third hook is activate_mm, which is called from the arch-specific
activate_mm() macro/function, and so doesn't need stub versions for
other architectures. It's called when an mm is first used.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: linux-arch@vger.kernel.org
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Ugly ifdef, but should handle all 64bit platforms that have suitable
zones. On some like Altix it's probably impossible without IOMMU
use to get memory <4GB this way, but they have to live with that.
Signed-off-by: Andi Kleen <ak@suse.de>
Do this really early in the 2.6.22-rc series, so that we'll get
feedback. And don't change by half measures. Just cut the default
dirty limit to a quarter of what it was, and see if anybody even
notices.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page_test_and_clear_dirty primitive really consists of two
operations, page_test_dirty and the page_clear_dirty. The combination
of the two is not an atomic operation, so it makes more sense to have
two separate operations instead of one.
In addition to the improved readability of the s390 version of
SetPageUptodate, it now avoids the page_test_dirty operation which is
an insert-storage-key-extended (iske) instruction which is an expensive
operation.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
NR_FILE_PAGES must be accounted for depending on the zone that the page
belongs to. If we replace the page in the radix tree then we may have to
shift the count to another zone.
Suggested-by: Ethan Solomita <solo@google.com>
Eventually-typed-in-by: Christoph Lameter <clameter@sgi.com>
Cc: Martin Bligh <mbligh@mbligh.org>
Cc: <stable@kernel.org>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
I only have CONFIG_NUMA=y for build testing: surprised when trying a memhog
to see lots of other processes killed with "No available memory
(MPOL_BIND)". memhog is killed correctly once we initialize nodemask in
constrained_alloc().
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Acked-by: William Irwin <bill.irwin@oracle.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
oom_kill_task() calls __oom_kill_task() to OOM kill a selected task.
When finding other threads that share an mm with that task, we need to
kill those individual threads and not the same one.
(Bug introduced by f2a2a7108a)
Acked-by: William Irwin <bill.irwin@oracle.com>
Acked-by: Christoph Lameter <clameter@engr.sgi.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Andrew Morton <akpm@osdl.org>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
num_physpages is not exported out in mm/nommu.c, so the ip_conntrack module
link will fail.
Signed-off-by: Bryan Wu <bryan.wu@analog.com>
Acked-By: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
[S390] cio: Fix handling of interrupt for csch().
[S390] page_mkclean data corruption.
Mention the slab name when listing corrupt objects. Although the function
that released the memory is mentioned, that is frequently ambiguous as such
functions often release several pieces of memory.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The git commit c2fda5fed8 which
added the page_test_and_clear_dirty call to page_mkclean and the
git commit 7658cc2892 which fixes
the "nasty and subtle race in shared mmap'ed page writeback"
problem in clear_page_dirty_for_io cause data corruption on s390.
The effect of the two changes is that for every call to
clear_page_dirty_for_io a page_test_and_clear_dirty is done. If
the per page dirty bit is set set_page_dirty is called. Strangly
clear_page_dirty_for_io is called for not-uptodate pages, e.g.
over this call-chain:
[<000000000007c0f2>] clear_page_dirty_for_io+0x12a/0x130
[<000000000007c494>] generic_writepages+0x258/0x3e0
[<000000000007c692>] do_writepages+0x76/0x7c
[<00000000000c7a26>] __writeback_single_inode+0xba/0x3e4
[<00000000000c831a>] sync_sb_inodes+0x23e/0x398
[<00000000000c8802>] writeback_inodes+0x12e/0x140
[<000000000007b9ee>] wb_kupdate+0xd2/0x178
[<000000000007cca2>] pdflush+0x162/0x23c
The bad news now is that page_test_and_clear_dirty might claim
that a not-uptodate page is dirty since SetPageUptodate which
resets the per page dirty bit has not yet been called. The page
writeback that follows clobbers the data on disk.
The simplest solution to this problem is to move the call to
page_test_and_clear_dirty under the "if (page_mapped(page))".
If a file backed page is mapped it is uptodate.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Fix the bug, that reading into xip mapping from /dev/zero fills the user
page table with ZERO_PAGE() entries. Later on, xip cannot tell which pages
have been ZERO_PAGE() filled by access to a sparse mapping, and which ones
origin from /dev/zero. It will unmap ZERO_PAGE from all mappings when
filling the sparse hole with data. xip does now use its own zeroed page
for its sparse mappings. Please apply.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sys_madvise has down_write of mmap_sem, then madvise_remove calls
vmtruncate_range which takes i_mutex and i_alloc_sem: no, we can easily devise
deadlocks from that ordering.
madvise_remove drop mmap_sem while calling vmtruncate_range: luckily, since
madvise_remove doesn't split or merge vmas, it's easy to handle this case with
a NULL prev, without restructuring sys_madvise. (Though sad to retake
mmap_sem when it's unlikely to be needed, and certainly down_read is
sufficient for MADV_REMOVE, unlike the other madvices.)
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
shmem_truncate_range has its own truncate_inode_pages_range, to free any pages
racily instantiated while it was in progress: a SHMEM_PAGEIN flag is set when
this might have happened. But holepunching gets no chance to clear that flag
at the start of vmtruncate_range, so it's always set (unless a truncate came
just before), so holepunch almost always does this second
truncate_inode_pages_range.
shmem holepunch has unlikely swap<->file races hereabouts whatever we do
(without a fuller rework than is fit for this release): I was going to skip
the second truncate in the punch_hole case, but Miklos points out that would
make holepunch correctness more vulnerable to swapoff. So keep the second
truncate, but follow it by an unmap_mapping_range to eliminate the
disconnected pages (freed from pagecache while still mapped in userspace) that
it might have left behind.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Miklos Szeredi observes that during truncation of shmem page directories,
info->lock is released to improve latency (after lowering i_size and
next_index to exclude races); but this is quite wrong for holepunching, which
receives no such protection from i_size or next_index, and is left vulnerable
to races with shmem_unuse, shmem_getpage and shmem_writepage.
Hold info->lock throughout when holepunching? No, any user could prevent
rescheduling for far too long. Instead take info->lock just when needed: in
shmem_free_swp when removing the swap entries, and whenever removing a
directory page from the level above. But so long as we remove before
scanning, we can safely skip taking the lock at the lower levels, except at
misaligned start and end of the hole.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Miklos Szeredi observes BUG_ON(!entry) in shmem_writepage() triggered in rare
circumstances, because shmem_truncate_range() erroneously removes partially
truncated directory pages at the end of the range: later reclaim on pages
pointing to these removed directories triggers the BUG. Indeed, and it can
also cause data loss beyond the hole.
Fix this as in the patch proposed by Miklos, but distinguish between "limit"
(how far we need to search: ignore truncation's next_index optimization in the
holepunch case - if there are races it's more consistent to act on the whole
range specified) and "upper_limit" (how far we can free directory pages:
generally we must be careful to keep partially punched pages, but can relax at
end of file - i_size being held stable by i_mutex).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cs>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a small problem in handling page bounce.
At the moment blk_max_pfn equals max_pfn, which is in fact not maximum
possible _number_ of a page frame, but the _amount_ of page frames. For
example for the 32bit x86 node with 4Gb RAM, max_pfn = 0x100000, but not
0xFFFF.
request_queue structure has a member q->bounce_pfn and queue needs bounce
pages for the pages _above_ this limit. This routine is handled by
blk_queue_bounce(), where the following check is produced:
if (q->bounce_pfn >= blk_max_pfn)
return;
Assume, that a driver has set q->bounce_pfn to 0xFFFF, but blk_max_pfn
equals 0x10000. In such situation the check above fails and for each bio
we always fall down for iterating over pages tied to the bio.
I want to notice, that for quite a big range of device drivers (ide, md,
...) such problem doesn't happen because they use BLK_BOUNCE_ANY for
bounce_pfn. BLK_BOUNCE_ANY is defined as blk_max_pfn << PAGE_SHIFT, and
then the check above doesn't fail. But for other drivers, which obtain
reuired value from drivers, it fails. For example sata_nv uses
ATA_DMA_MASK or dev->dma_mask.
I propose to use (max_pfn - 1) for blk_max_pfn. And the same for
blk_max_low_pfn. The patch also cleanses some checks related with
bounce_pfn.
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Supply a get_unmapped_area() to fix NOMMU SYSV SHM support.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Looking at oom_kill.c, found that the intention to not kill the selected
process if any of its children/siblings has OOM_DISABLE set, is not being
met.
Signed-off-by: Ankita Garg <ankita@in.ibm.com>
Acked-by: Nick Piggin <npiggin@suse.de>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The current NFS client congestion logic is severly broken, it marks the
backing device congested during each nfs_writepages() call but doesn't
mirror this in nfs_writepage() which makes for deadlocks. Also it
implements its own waitqueue.
Replace this by a more regular congestion implementation that puts a cap on
the number of active writeback pages and uses the bdi congestion waitqueue.
Also always use an interruptible wait since it makes sense to be able to
SIGKILL the process even for mounts without 'intr'.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Trond Myklebust <trond.myklebust@fys.uio.no>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch fixes a user-triggerable oops that was reported by Leonid
Ananiev as archived at http://lkml.org/lkml/2007/2/8/337.
dio writes invalidate clean pages that intersect the written region so that
subsequent buffered reads go to disk to read the new data. If this fails
the interface tries to tell the caller that the cache is inconsistent by
returning EIO.
Before this patch we had the problem where this invalidation failure would
clobber -EIOCBQUEUED as it made its way from fs/direct-io.c to fs/aio.c.
Both fs/aio.c and bio completion call aio_complete() and we reference freed
memory, usually oopsing.
This patch addresses this problem by invalidating before the write so that
we can cleanly return -EIO before ->direct_IO() has had a chance to return
-EIOCBQUEUED.
There is a compromise here. During the dio write we can fault in mmap()ed
pages which intersect the written range with get_user_pages() if the user
provided them for the source buffer. This is a crazy thing to do, but we
can make it mostly work in most cases by trying the invalidation again.
The compromise is that we won't return an error if this second invalidation
fails if it's an AIO write and we have -EIOCBQUEUED.
This was tested by having two processes race performing large O_DIRECT and
buffered ordered writes. Within minutes ext3 would see a race between
ext3_releasepage() and jbd holding a reference on ordered data buffers and
would cause invalidation to fail, panicing the box. The test can be found
in the 'aio_dio_bugs' test group in test.kernel.org/autotest. After this
patch the test passes.
Signed-off-by: Zach Brown <zach.brown@oracle.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>
Cc: Leonid Ananiev <leonid.i.ananiev@linux.intel.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
madvise(MADV_REMOVE) can go into an infinite loop or cause an oops if the
call covers a region from the start of a vma, and extending past that vma.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently we do not check for vma flags if sys_move_pages is called to move
individual pages. If sys_migrate_pages is called to move pages then we
check for vm_flags that indicate a non migratable vma but that still
includes VM_LOCKED and we can migrate mlocked pages.
Extract the vma_migratable check from mm/mempolicy.c, fix it and put it
into migrate.h so that is can be used from both locations.
Problem was spotted by Lee Schermerhorn
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
shmem's super_operations were missed from the recent const-ification;
and simple_fill_super()'s, which can share with get_sb_pseudo()'s.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Josef 'Jeff' Sipek <jsipek@cs.sunysb.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix invalidate_inode_pages2_range() so that it does not immediately exit
just because a single page in the specified range could not be removed.
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page_lock_anon_vma() uses spin_lock() to block RCU. This doesn't work with
PREEMPT_RCU, we have to do rcu_read_lock() explicitely. Otherwise, it is
theoretically possible that slab returns anon_vma's memory to the system
before we do spin_unlock(&anon_vma->lock).
[ Hugh points out that this only matters for PREEMPT_RCU, which isn't merged
yet, and may never be. Regardless, this patch is conceptually the
right thing to do, even if it doesn't matter at this point. - Linus ]
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
throttle_vm_writeout() is designed to wait for the dirty levels to subside.
But if the caller holds IO or FS locks, we might be holding up that writeout.
So change it to take a single nap to give other devices a chance to clean some
memory, then return.
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Pete Zaitcev <zaitcev@redhat.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The code is seemingly trying to make sure that rb_next() brings us to
successive increasing vma entries.
But the two variables, prev and pend, used to perform these checks, are
never advanced.
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Andrea Arcangeli <andrea@novell.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Rename PG_checked to PG_owner_priv_1 to reflect its availablilty as a
private flag for use by the owner/allocator of the page. In the case of
pagecache pages (which might be considered to be owned by the mm),
filesystems may use the flag.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
shmem_{nopage,mmap} are no longer used in ipc/shm.c
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The alien cache is a per cpu per node array allocated for every slab on the
system. Currently we size this array for all nodes that the kernel does
support. For IA64 this is 1024 nodes. So we allocate an array with 1024
objects even if we only boot a system with 4 nodes.
This patch uses "nr_node_ids" to determine the number of possible nodes
supported by a hardware configuration and only allocates an alien cache
sized for possible nodes.
The initialization of nr_node_ids occurred too late relative to the bootstrap
of the slab allocator and so I moved the setup_nr_node_ids() into
free_area_init_nodes().
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
highest_possible_node_id() is currently used to calculate the last possible
node idso that the network subsystem can figure out how to size per node
arrays.
I think having the ability to determine the maximum amount of nodes in a
system at runtime is useful but then we should name this entry
correspondingly, it should return the number of node_ids, and the the value
needs to be setup only once on bootup. The node_possible_map does not
change after bootup.
This patch introduces nr_node_ids and replaces the use of
highest_possible_node_id(). nr_node_ids is calculated on bootup when the
page allocators pagesets are initialized.
[deweerdt@free.fr: fix oops]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Frederik Deweerdt <frederik.deweerdt@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
bind_zonelist() can create zero-length zonelist if there is a
memory-less-node. This patch checks the length of zonelist. If length is
0, returns -EINVAL.
tested on ia64/NUMA with memory-less-node.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When NFSD receives a write request, the data is typically in a number of
1448 byte segments and writev is used to collect them together.
Unfortunately, generic_file_buffered_write passes these to the filesystem
one at a time, so an e.g. 32K over-write becomes a series of partial-page
writes to each page, causing the filesystem to have to pre-read those pages
- wasted effort.
generic_file_buffered_write handles one segment of the vector at a time as
it has to pre-fault in each segment to avoid deadlocks. When writing from
kernel-space (and nfsd does) this is not an issue, so
generic_file_buffered_write does not need to break and iovec from nfsd into
little pieces.
This patch avoids the splitting when get_fs is KERNEL_DS as it is
from NFSd.
This issue was introduced by commit 6527c2bdf1
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Norman Weathers <norman.r.weathers@conocophillips.com>
Cc: Vladimir V. Saveliev <vs@namesys.com>
Signed-off-by: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Paper bag time. Thanks to Randy for noticing that I didn't actually assign
'present' to anything.
Unfortunately my original patch passed the few simple test cases I gave it,
purely by coincidence.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Fix mincore-anon patch to compile with CONFIG_SWAP=n
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Many struct inode_operations in the kernel can be "const". Marking them const
moves these to the .rodata section, which avoids false sharing with potential
dirty data. In addition it'll catch accidental writes at compile time to
these shared resources.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make mincore work for anon mappings, nonlinear, and migration entries.
Based on patch from Linus Torvalds <torvalds@linux-foundation.org>.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a NOPFN_REFAULT return code for vm_ops->nopfn() equivalent to
NOPAGE_REFAULT for vmops->nopage() indicating that the handler requests a
re-execution of the faulting instruction
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a vm_insert_pfn helper, so that ->fault handlers can have nopfn
functionality by installing their own pte and returning NULL.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change a hard-coded constant 0 to the symbolic equivalent NOTIFY_DONE in
the ratelimit_handler() CPU notifier handler function.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
A variety of (mostly) innocuous fixes to the embedded kernel-doc content in
source files, including:
* make multi-line initial descriptions single line
* denote some function names, constants and structs as such
* change erroneous opening '/*' to '/**' in a few places
* reword some text for clarity
Signed-off-by: Robert P. J. Day <rpjday@mindspring.com>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Convert all calls to invalidate_inode_pages() into open-coded calls to
invalidate_mapping_pages().
Leave the invalidate_inode_pages() wrapper in place for now, marked as
deprecated.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It makes no sense to me to export invalidate_inode_pages() and not
invalidate_mapping_pages() and I actually need invalidate_mapping_pages()
because of its range specification ability...
akpm: also remove the export of invalidate_inode_pages() by making it an
inlined wrapper.
Signed-off-by: Anton Altaparmakov <aia21@cantab.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kmem_cache_free() was missing the check for freeing held locks.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When kernel unmaps an address range, it needs to transfer PTE state into
page struct. Currently, kernel transfer access bit via
mark_page_accessed(). The call to mark_page_accessed in the unmap path
doesn't look logically correct.
At unmap time, calling mark_page_accessed will causes page LRU state to be
bumped up one step closer to more recently used state. It is causing quite
a bit headache in a scenario when a process creates a shmem segment, touch
a whole bunch of pages, then unmaps it. The unmapping takes a long time
because mark_page_accessed() will start moving pages from inactive to
active list.
I'm not too much concerned with moving the page from one list to another in
LRU. Sooner or later it might be moved because of multiple mappings from
various processes. But it just doesn't look logical that when user asks a
range to be unmapped, it's his intention that the process is no longer
interested in these pages. Moving those pages to active list (or bumping
up a state towards more active) seems to be an over reaction. It also
prolongs unmapping latency which is the core issue I'm trying to solve.
As suggested by Peter, we should still preserve the info on pte young
pages, but not more.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ken Chen <kenchen@google.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
shmem backed file does not have page writeback, nor it participates in
backing device's dirty or writeback accounting. So using generic
__set_page_dirty_nobuffers() for its .set_page_dirty aops method is a bit
overkill. It unnecessarily prolongs shm unmap latency.
For example, on a densely populated large shm segment (sevearl GBs), the
unmapping operation becomes painfully long. Because at unmap, kernel
transfers dirty bit in PTE into page struct and to the radix tree tag. The
operation of tagging the radix tree is particularly expensive because it
has to traverse the tree from the root to the leaf node on every dirty
page. What's bothering is that radix tree tag is used for page write back.
However, shmem is memory backed and there is no page write back for such
file system. And in the end, we spend all that time tagging radix tree and
none of that fancy tagging will be used. So let's simplify it by introduce
a new aops __set_page_dirty_no_writeback and this will speed up shm unmap.
Signed-off-by: Ken Chen <kenchen@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
As Andi pointed out: CONFIG_GENERIC_ISA_DMA only disables the ISA DMA
channel management. Other functionality may still expect GFP_DMA to
provide memory below 16M. So we need to make sure that CONFIG_ZONE_DMA is
set independent of CONFIG_GENERIC_ISA_DMA. Undo the modifications to
mm/Kconfig where we made ZONE_DMA dependent on GENERIC_ISA_DMA and set
theses explicitly in each arches Kconfig.
Reviews must occur for each arch in order to determine if ZONE_DMA can be
switched off. It can only be switched off if we know that all devices
supported by a platform are capable of performing DMA transfers to all of
memory (Some arches already support this: uml, avr32, sh sh64, parisc and
IA64/Altix).
In order to switch ZONE_DMA off conditionally, one would have to establish
a scheme by which one can assure that no drivers are enabled that are only
capable of doing I/O to a part of memory, or one needs to provide an
alternate means of performing an allocation from a specific range of memory
(like provided by alloc_pages_range()) and insure that all drivers use that
call. In that case the arches alloc_dma_coherent() may need to be modified
to call alloc_pages_range() instead of relying on GFP_DMA.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Make ZONE_DMA optional in core code.
- ifdef all code for ZONE_DMA and related definitions following the example
for ZONE_DMA32 and ZONE_HIGHMEM.
- Without ZONE_DMA, ZONE_HIGHMEM and ZONE_DMA32 we get to a ZONES_SHIFT of
0.
- Modify the VM statistics to work correctly without a DMA zone.
- Modify slab to not create DMA slabs if there is no ZONE_DMA.
[akpm@osdl.org: cleanup]
[jdike@addtoit.com: build fix]
[apw@shadowen.org: Simplify calculation of the number of bits we need for ZONES_SHIFT]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <willy@debian.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch simply defines CONFIG_ZONE_DMA for all arches. We later do special
things with CONFIG_ZONE_DMA after the VM and an arch are prepared to work
without ZONE_DMA.
CONFIG_ZONE_DMA can be defined in two ways depending on how an architecture
handles ISA DMA.
First if CONFIG_GENERIC_ISA_DMA is set by the arch then we know that the arch
needs ZONE_DMA because ISA DMA devices are supported. We can catch this in
mm/Kconfig and do not need to modify arch code.
Second, arches may use ZONE_DMA in an unknown way. We set CONFIG_ZONE_DMA for
all arches that do not set CONFIG_GENERIC_ISA_DMA in order to insure backwards
compatibility. The arches may later undefine ZONE_DMA if their arch code has
been verified to not depend on ZONE_DMA.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <willy@debian.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patchset follows up on the earlier work in Andrew's tree to reduce the
number of zones. The patches allow to go to a minimum of 2 zones. This one
allows also to make ZONE_DMA optional and therefore the number of zones can be
reduced to one.
ZONE_DMA is usually used for ISA DMA devices. There are a number of reasons
why we would not want to have ZONE_DMA
1. Some arches do not need ZONE_DMA at all.
2. With the advent of IOMMUs DMA zones are no longer needed.
The necessity of DMA zones may drastically be reduced
in the future. This patchset allows a compilation of
a kernel without that overhead.
3. Devices that require ISA DMA get rare these days. All
my systems do not have any need for ISA DMA.
4. The presence of an additional zone unecessarily complicates
VM operations because it must be scanned and balancing
logic must operate on its.
5. With only ZONE_NORMAL one can reach the situation where
we have only one zone. This will allow the unrolling of many
loops in the VM and allows the optimization of varous
code paths in the VM.
6. Having only a single zone in a NUMA system results in a
1-1 correspondence between nodes and zones. Various additional
optimizations to critical VM paths become possible.
Many systems today can operate just fine with a single zone. If you look at
what is in ZONE_DMA then one usually sees that nothing uses it. The DMA slabs
are empty (Some arches use ZONE_DMA instead of ZONE_NORMAL, then ZONE_NORMAL
will be empty instead).
On all of my systems (i386, x86_64, ia64) ZONE_DMA is completely empty. Why
constantly look at an empty zone in /proc/zoneinfo and empty slab in
/proc/slabinfo? Non i386 also frequently have no need for ZONE_DMA and zones
stay empty.
The patchset was tested on i386 (UP / SMP), x86_64 (UP, NUMA) and ia64 (NUMA).
The RFC posted earlier (see
http://marc.theaimsgroup.com/?l=linux-kernel&m=115231723513008&w=2) had lots
of #ifdefs in them. An effort has been made to minize the number of #ifdefs
and make this as compact as possible. The job was made much easier by the
ongoing efforts of others to extract common arch specific functionality.
I have been running this for awhile now on my desktop and finally Linux is
using all my available RAM instead of leaving the 16MB in ZONE_DMA untouched:
christoph@pentium940:~$ cat /proc/zoneinfo
Node 0, zone Normal
pages free 4435
min 1448
low 1810
high 2172
active 241786
inactive 210170
scanned 0 (a: 0 i: 0)
spanned 524224
present 524224
nr_anon_pages 61680
nr_mapped 14271
nr_file_pages 390264
nr_slab_reclaimable 27564
nr_slab_unreclaimable 1793
nr_page_table_pages 449
nr_dirty 39
nr_writeback 0
nr_unstable 0
nr_bounce 0
cpu: 0 pcp: 0
count: 156
high: 186
batch: 31
cpu: 0 pcp: 1
count: 9
high: 62
batch: 15
vm stats threshold: 20
cpu: 1 pcp: 0
count: 177
high: 186
batch: 31
cpu: 1 pcp: 1
count: 12
high: 62
batch: 15
vm stats threshold: 20
all_unreclaimable: 0
prev_priority: 12
temp_priority: 12
start_pfn: 0
This patch:
In two places in the VM we use ZONE_DMA to refer to the first zone. If
ZONE_DMA is optional then other zones may be first. So simply replace
ZONE_DMA with zone 0.
This also fixes ZONETABLE_PGSHIFT. If we have only a single zone then
ZONES_PGSHIFT may become 0 because there is no need anymore to encode the zone
number related to a pgdat. However, we still need a zonetable to index all
the zones for each node if this is a NUMA system. Therefore define
ZONETABLE_SHIFT unconditionally as the offset of the ZONE field in page flags.
[apw@shadowen.org: fix mismerge]
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Matthew Wilcox <willy@debian.org>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
