08 May, 2007
40 commits
-
Address spaces contain an allocation flag that specifies restriction on the
zone for pages placed in the mapping. I.e. some device may require pages
to be allocated from a DMA zone. Block devices may not be able to use
pages from HIGHMEM.Memory policies and the common use of page migration works only on the
highest zone. If the address space does not allow allocation from the
highest zone then the pages in the address space are not migratable simply
because we can only allocate memory for a specified node if we allow
allocation for the highest zone on each node.Acked-by: Hugh Dickins
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
SLOB doesn't calculate correct page order when page size is not 4KB. This
patch fixes it with using get_order() instead of find_order() which is SLOB
version of get_order().Signed-off-by: Akinobu Mita
Acked-by: Matt Mackall
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
If hugetlbfs module_init() fails, hugetlbfs_vfsmount is not initialized and
shmget() with SHM_HUGETLB flag will cause NULL pointer dereference.Signed-off-by: Akinobu Mita
Acked-by: William Irwin
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There is no user remaining and I have never seen any use of that flag.
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
SLAB_CTOR atomic is never used which is no surprise since I cannot imagine
that one would want to do something serious in a constructor or destructor.
In particular given that the slab allocators run with interrupts disabled.
Actions in constructors and destructors are by their nature very limited
and usually do not go beyond initializing variables and list operations.(The i386 pgd ctor and dtors do take a spinlock in constructor and
destructor..... I think that is the furthest we go at this point.)There is no flag passed to the destructor so removing SLAB_CTOR_ATOMIC also
establishes a certain symmetry.Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Acked-by: William Irwin
Cc: Paul Mackerras
Cc: Richard Henderson
Cc: Ivan Kokshaysky
Cc: Russell King
Cc: David Howells
Cc: Andi Kleen
Cc: "Luck, Tony"
Cc: Kyle McMartin
Cc: Grant Grundler
Cc: Matthew Wilcox
Cc: "David S. Miller"
Cc: Adam Litke
Cc: David Gibson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Cc: Paul Mackerras
Cc: Richard Henderson
Cc: Ivan Kokshaysky
Cc: Russell King
Cc: David Howells
Cc: Andi Kleen
Cc: "Luck, Tony"
Cc: Kyle McMartin
Cc: Grant Grundler
Cc: Matthew Wilcox
Cc: "David S. Miller"
Cc: William Irwin
Cc: Adam Litke
Cc: David Gibson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Generic hugetlb_get_unmapped_area() now handles MAP_FIXED by just calling
prepare_hugepage_range()Signed-off-by: Benjamin Herrenschmidt
Acked-by: William Irwin
Cc: Paul Mackerras
Cc: Richard Henderson
Cc: Ivan Kokshaysky
Cc: Russell King
Cc: David Howells
Cc: Andi Kleen
Cc: "Luck, Tony"
Cc: Kyle McMartin
Cc: Grant Grundler
Cc: Matthew Wilcox
Cc: "David S. Miller"
Cc: Adam Litke
Cc: David Gibson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Handle MAP_FIXED in x86_64 arch_get_unmapped_area(), simple case, just return
the address as passed inSigned-off-by: Benjamin Herrenschmidt
Cc: Andi Kleen
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Handle MAP_FIXED in hugetlb_get_unmapped_area on sparc64 by just using
prepare_hugepage_range()Signed-off-by: Benjamin Herrenschmidt
Acked-by: William Irwin
Cc: "David S. Miller"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Handle MAP_FIXED in parisc arch_get_unmapped_area(), just return the address.
We might want to also check for possible cache aliasing issues now that we get
called in that case (like ARM or MIPS), leave a comment for the maintainers to
pick up.Signed-off-by: Benjamin Herrenschmidt
Cc: Kyle McMartin
Cc: Grant Grundler
Cc: Matthew Wilcox
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Handle MAP_FIXED in ia64 arch_get_unmapped_area and
hugetlb_get_unmapped_area(), just call prepare_hugepage_range in the later and
is_hugepage_only_range() in the former.Signed-off-by: Benjamin Herrenschmidt
Acked-by: William Irwin
Cc: "Luck, Tony"
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Handle MAP_FIXED in i386 hugetlb_get_unmapped_area(), just call
prepare_hugepage_range.Signed-off-by: Benjamin Herrenschmidt
Acked-by: William Irwin
Cc: Andi Kleen
Cc: Adam Litke
Cc: David Gibson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Handle MAP_FIXED in arch_get_unmapped_area on frv. Trivial case, just return
the address.Signed-off-by: Benjamin Herrenschmidt
Cc: David Howells
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
ARM already had a case for MAP_FIXED in arch_get_unmapped_area() though it was
not called before. Fix the comment to reflect that it will now be called.Signed-off-by: Benjamin Herrenschmidt
Acked-by: Russell King
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Handle MAP_FIXED in alpha's arch_get_unmapped_area(), simple case, just return
the address as passed inSigned-off-by: Benjamin Herrenschmidt
Cc: Richard Henderson
Cc: Ivan Kokshaysky
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The current get_unmapped_area code calls the f_ops->get_unmapped_area or the
arch one (via the mm) only when MAP_FIXED is not passed. That makes it
impossible for archs to impose proper constraints on regions of the virtual
address space. To work around that, get_unmapped_area() then calls some
hugetlbfs specific hacks.This cause several problems, among others:
- It makes it impossible for a driver or filesystem to do the same thing
that hugetlbfs does (for example, to allow a driver to use larger page sizes
to map external hardware) if that requires applying a constraint on the
addresses (constraining that mapping in certain regions and other mappings
out of those regions).- Some archs like arm, mips, sparc, sparc64, sh and sh64 already want
MAP_FIXED to be passed down in order to deal with aliasing issues. The code
is there to handle it... but is never called.This series of patches moves the logic to handle MAP_FIXED down to the various
arch/driver get_unmapped_area() implementations, and then changes the generic
code to always call them. The hugetlbfs hacks then disappear from the generic
code.Since I need to do some special 64K pages mappings for SPEs on cell, I need to
work around the first problem at least. I have further patches thus
implementing a "slices" layer that handles multiple page sizes through slices
of the address space for use by hugetlbfs, the SPE code, and possibly others,
but it requires that serie of patches first/There is still a potential (but not practical) issue due to the fact that
filesystems/drivers implemeting g_u_a will effectively bypass all arch checks.
This is not an issue in practice as the only filesystems/drivers using that
hook are doing so for arch specific purposes in the first place.There is also a problem with mremap that will completely bypass all arch
checks. I'll try to address that separately, I'm not 100% certain yet how,
possibly by making it not work when the vma has a file whose f_ops has a
get_unmapped_area callback, and by making it use is_hugepage_only_range()
before expanding into a new area.Also, I want to turn is_hugepage_only_range() into a more generic
is_normal_page_range() as that's really what it will end up meaning when used
in stack grow, brk grow and mremap.None of the above "issues" however are introduced by this patch, they are
already there, so I think the patch can go ini for 2.6.22.This patch:
Handle MAP_FIXED in powerpc's arch_get_unmapped_area() in all 3
implementations of it.Signed-off-by: Benjamin Herrenschmidt
Acked-by: William Irwin
Cc: Paul Mackerras
Cc: Richard Henderson
Cc: Ivan Kokshaysky
Cc: Russell King
Cc: David Howells
Cc: Andi Kleen
Cc: "Luck, Tony"
Cc: Kyle McMartin
Cc: Grant Grundler
Cc: Matthew Wilcox
Cc: "David S. Miller"
Cc: Adam Litke
Cc: David Gibson
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Cc: Nick Piggin
Cc: Christoph Lameter
Cc: Martin J. Bligh
Signed-off-by: David Rientjes
Cc:
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Benjamin LaHaise
Cc: Christoph Lameter
Cc: Paul Jackson
Cc: Ethan Solomita
Cc: David Rientjes
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Akinobu Mita
Cc: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
It is not necessary to tell the slab allocators to align to a cacheline
if an explicit alignment was already specified. It is rather confusing
to specify multiple alignments.Make sure that the call sites only use one form of alignment.
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This patch provides a new macro
KMEM_CACHE(, )
to simplify slab creation. KMEM_CACHE creates a slab with the name of the
struct, with the size of the struct and with the alignment of the struct.
Additional slab flags may be specified if necessary.Example
struct test_slab {
int a,b,c;
struct list_head;
} __cacheline_aligned_in_smp;test_slab_cache = KMEM_CACHE(test_slab, SLAB_PANIC)
will create a new slab named "test_slab" of the size sizeof(struct
test_slab) and aligned to the alignment of test slab. If it fails then we
panic.Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
invalidate_bdev() is superfluous when truncate_inode_pages() is also
called. do call invalidate_bh_lrus() though, to avoid stale pointers.Signed-off-by: Peter Zijlstra
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Remove duplicate work in kill_bdev().
It currently invalidates and then truncates the bdev's mapping.
invalidate_mapping_pages() will opportunistically remove pages from the
mapping. And truncate_inode_pages() will forcefully remove all pages.The only thing truncate doesn't do is flush the bh lrus. So do that
explicitly. This avoids (very unlikely) but possible invalid lookup
results if the same bdev is quickly re-issued.It also will prevent extreme kernel latencies which are observed when
blockdevs which have a large amount of pagecache are unmounted, by avoiding
invalidate_mapping_pages() on that path. invalidate_mapping_pages() has no
cond_resched (it can be called under spinlock), whereas truncate_inode_pages()
has one.[akpm@linux-foundation.org: restore nrpages==0 optimisation]
Signed-off-by: Peter Zijlstra
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Remove the destroy_dirty_buffers argument from invalidate_bdev(), it hasn't
been used in 6 years (so akpm says).find * -name \*.[ch] | xargs grep -l invalidate_bdev |
while read file; do
quilt add $file;
sed -ie 's/invalidate_bdev(\([^,]*\),[^)]*)/invalidate_bdev(\1)/g' $file;
doneSigned-off-by: Peter Zijlstra
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Avoid down_write of the mmap_sem in madvise when we can help it.
Acked-by: Hugh Dickins
Signed-off-by: Nick Piggin
Cc: Rik van Riel
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Matthias Kaehlcke
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
kmem_cache_create() for slob doesn't handle SLAB_PANIC.
Signed-off-by: Matt Mackall
Signed-off-by: Akinobu Mita
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
I ported this to sparc64 as per the patch below, tested on UP SunBlade1500 and
24 cpu Niagara T1000.Signed-off-by: David S. Miller
Signed-off-by: Christoph Lameter
Cc: "David S. Miller"
Cc: Andi Kleen
Cc: "Luck, Tony"
Cc: William Lee Irwin III
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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 hasconfig NR_QUICK
int
default 2If 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(, , )
Page table pages can be freed using:
quicklist_free(, , )
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
Cc: "David S. Miller"
Cc: Andi Kleen
Cc: "Luck, Tony"
Cc: William Lee Irwin III
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Add the tool which gets reports about slabs to the VM documentation directory.
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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_freeSigned-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Christoph Lameter
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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+0x70/0x2e0cat /sys/slab/kmalloc-128/free_calls
558
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+0x20/0x40SLAB_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
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
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
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
