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Avoid pointer type value compared with 0 to make code clear.
./tools/testing/radix-tree/maple.c:34142:15-16: WARNING comparing pointer to 0.
Link: https://lkml.kernel.org/r/[email protected]
Reported-by: Abaci Robot <[email protected]>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7696
Signed-off-by: Jiapeng Chong <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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mas_preallocate() defaults to requesting 1 node for preallocation and then
,depending on the type of store, will update the request variable. There
isn't a check for a slot store type, so slot stores are preallocating the
default 1 node. Slot stores do not require any additional nodes, so add a
check for the slot store case that will bypass node_count_gfp(). Update
the tests to reflect that slot stores do not require allocations.
User visible effects of this bug include increased memory usage from the
unneeded node that was allocated.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 0b8bb544b1a7 ("maple_tree: update mas_preallocate() testing")
Signed-off-by: Sidhartha Kumar <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: Peng Zhang <[email protected]>
Cc: <[email protected]> [6.6+]
Signed-off-by: Andrew Morton <[email protected]>
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Now that the status of the maple state is outside of the node, the
mas_searchable() function can be dropped for easier open-coding of what is
going on.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Peng Zhang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The maple tree node is overloaded to keep status as well as the active
node. This, unfortunately, results in a re-walk on underflow or overflow.
Since the maple state has room, the status can be placed in its own enum
in the structure. Once an underflow/overflow is detected, certain modes
can restore the status to active and others may need to re-walk just that
one node to see the entry.
The status being an enum has the benefit of detecting unhandled status in
switch statements.
[[email protected]: fix comments about MAS_*]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: update forking to separate maple state and node]
Link: https://lkml.kernel.org/r/[email protected]
[[email protected]: fix mas_prev() state separation code]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Peng Zhang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Analysis of the mas_for_each() iteration showed that there is a
significant time spent finding the end of a node. This time can be
greatly reduced if the end of the node is cached in the maple state. Care
must be taken to update & invalidate as necessary.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Peng Zhang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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__mas_set_range() was created to shortcut resetting the maple state and a
debug check was added to the caller (the vma iterator) to ensure the
internal maple state remains safe to use. Move the debug check from the
vma iterator into the maple tree itself so other users do not incorrectly
use the advanced maple state modification.
Fallout from this change include a large amount of debug setup needed to
be moved to earlier in the header, and the maple_tree.h radix-tree test
code needed to move the inclusion of the header to after the atomic
define. None of those changes have functional changes.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Peng Zhang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Skip other tests when BENCH is enabled so that performance can be measured
in user space.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peng Zhang <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mateusz Guzik <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Mike Christie <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Add test for mtree_dup().
Test by duplicating different maple trees and then comparing the two
trees. Includes tests for duplicating full trees and memory allocation
failures on different nodes.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peng Zhang <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mateusz Guzik <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Mike Christie <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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When kmem_cache_alloc_bulk() fails to allocate, leave the freed pointers
in the array. This enables a more accurate simulation of the kernel's
behavior and allows for testing potential double-free scenarios.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peng Zhang <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Cc: Christian Brauner <[email protected]>
Cc: Jonathan Corbet <[email protected]>
Cc: Mateusz Guzik <[email protected]>
Cc: Mathieu Desnoyers <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Michael S. Tsirkin <[email protected]>
Cc: Mike Christie <[email protected]>
Cc: Nicholas Piggin <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The bulk allocation is iterating through an array and storing enough
memory for the entire bulk allocation instead of a single array entry.
Only allocate an array element of the size set in the kmem_cache.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: cc86e0c2f306 ("radix tree test suite: add support for slab bulk APIs")
Signed-off-by: Liam R. Howlett <[email protected]>
Reported-by: Christophe JAILLET <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Pull xarray fixes from Matthew Wilcox:
- Fix a bug encountered by people using bittorrent where they'd get
NULL pointer dereferences on page cache lookups when using XFS
- Two documentation fixes
* tag 'xarray-6.6' of git://git.infradead.org/users/willy/xarray:
idr: fix param name in idr_alloc_cyclic() doc
xarray: Document necessary flag in alloc functions
XArray: Do not return sibling entries from xa_load()
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Since the mas_preallocate() calculation has been updated to be more
precise, the testing must also be updated to check for what is expected.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Peng Zhang <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The current preallocation strategy is to preallocate the absolute
worst-case allocation for a tree modification. The entry (or NULL) is
needed to know how many nodes are needed to write to the tree. Start by
adding the argument to the mas_preallocate() definition.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Peng Zhang <[email protected]>
Cc: Suren Baghdasaryan <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Add test for expanding range in RCU mode. If we use the fast path of the
slot store to expand range in RCU mode, this test will fail.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peng Zhang <[email protected]>
Reviewed-by: Liam R. Howlett <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Currently the pthread allocation for each array item is based on the size
of a pthread_t pointer and should be the size of the pthread_t structure,
so the allocation is under-allocating the correct size. Fix this by using
the size of each element in the pthreads array.
Static analysis cppcheck reported:
tools/testing/radix-tree/regression1.c:180:2: warning: Size of pointer
'threads' used instead of size of its data. [pointerSize]
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 1366c37ed84b ("radix tree test harness")
Signed-off-by: Colin Ian King <[email protected]>
Cc: Konstantin Khlebnikov <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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It is possible for xa_load() to observe a sibling entry pointing to
another sibling entry. An example:
Thread A: Thread B:
xa_store_range(xa, entry, 188, 191, gfp);
xa_load(xa, 191);
entry = xa_entry(xa, node, 63);
[entry is a sibling of 188]
xa_store_range(xa, entry, 184, 191, gfp);
if (xa_is_sibling(entry))
offset = xa_to_sibling(entry);
entry = xa_entry(xas->xa, node, offset);
[entry is now a sibling of 184]
It is sufficient to go around this loop until we hit a non-sibling entry.
Sibling entries always point earlier in the node, so we are guaranteed
to terminate this search.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Fixes: 6b24ca4a1a8d ("mm: Use multi-index entries in the page cache")
Cc: [email protected]
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Internal node counting was altered and the 64 bit test was updated,
however the 32bit test was missed.
Restore the 32bit test to a functional state.
Link: https://lore.kernel.org/linux-mm/CAMuHMdV4T53fOw7VPoBgPR7fP6RYqf=CBhD_y_vOg53zZX_DnA@mail.gmail.com/
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 541e06b772c1 ("maple_tree: remove GFP_ZERO from kmem_cache_alloc() and kmem_cache_alloc_bulk()")
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The xarray.c file contains the only call to radix_tree_node_rcu_free(),
and it comes with its own extern declaration for it. This means the
function definition causes a missing-prototype warning:
lib/radix-tree.c:288:6: error: no previous prototype for 'radix_tree_node_rcu_free' [-Werror=missing-prototypes]
Instead, move the declaration for this function to a new header that can
be included by both, and do the same for the radix_tree_node_cachep
variable that has the same underlying problem but does not cause a warning
with gcc.
[[email protected]: fix building radix tree test suite]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Arnd Bergmann <[email protected]>
Signed-off-by: Peng Zhang <[email protected]>
Cc: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The test functions are not needed after the module is removed, so mark
them as such. Add __exit to the module removal function. Some other
variables have been marked as const static as well.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Suggested-by: Andrew Morton <[email protected]>
Cc: David Binderman <[email protected]>
Cc: Peng Zhang <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Vernon Yang <[email protected]>
Cc: Wei Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The test code is less useful without debug, but can still do general
validations. Define mt_dump(), mas_dump() and mas_wr_dump() as a noop if
debug is not enabled and document it in the test module information that
more information can be obtained with another kernel config option.
MT_BUG_ON() will report a failures without tree dumps, and the output will
be less useful.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: David Binderman <[email protected]>
Cc: Peng Zhang <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Vernon Yang <[email protected]>
Cc: Wei Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Allow different formatting strings to be used when dumping the tree.
Currently supports hex and decimal.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: David Binderman <[email protected]>
Cc: Peng Zhang <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Vernon Yang <[email protected]>
Cc: Wei Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The maple tree node limits are implied by the parent. When walking up the
tree, the limit may not be known until a slot that does not have implied
limits are encountered. However, if the node is the left-most or
right-most node, the walking up to find that limit can be skipped.
This commit also fixes the debug/testing code that was not setting the
limit on walking down the tree as that optimization is not compatible with
this change.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Reviewed-by: Peng Zhang <[email protected]>
Cc: David Binderman <[email protected]>
Cc: Sergey Senozhatsky <[email protected]>
Cc: Vernon Yang <[email protected]>
Cc: Wei Yang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Add a test case to check whether the number of maple_alloc structures is
actually equal to mas->alloc->total.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Peng Zhang <[email protected]>
Cc: Liam R. Howlett <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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During the development of the maple tree, the strategy of freeing multiple
nodes changed and, in the process, the pivots were reused to store
pointers to dead nodes. To ensure the readers see accurate pivots, the
writers need to mark the nodes as dead and call smp_wmb() to ensure any
readers can identify the node as dead before using the pivot values.
There were two places where the old method of marking the node as dead
without smp_wmb() were being used, which resulted in RCU readers seeing
the wrong pivot value before seeing the node was dead. Fix this race
condition by using mte_set_node_dead() which has the smp_wmb() call to
ensure the race is closed.
Add a WARN_ON() to the ma_free_rcu() call to ensure all nodes being freed
are marked as dead to ensure there are no other call paths besides the two
updated paths.
This is necessary for the RCU mode of the maple tree.
Link: https://lkml.kernel.org/r/[email protected]
Fixes: 54a611b60590 ("Maple Tree: add new data structure")
Signed-off-by: Liam R. Howlett <[email protected]>
Signed-off-by: Suren Baghdasaryan <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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The parameter entry of mas_preallocate is not used, so drop it.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Vernon Yang <[email protected]>
Cc: Liam Howlett <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Preallocations are common in the VMA code to avoid allocating under
certain locking conditions. The preallocations must also cover the
worst-case scenario. Removing the GFP_ZERO flag from the
kmem_cache_alloc() (and bulk variant) calls will reduce the amount of time
spent zeroing memory that may not be used. Only zero out the necessary
area to keep track of the allocations in the maple state. Zero the entire
node prior to using it in the tree.
This required internal changes to node counting on allocation, so the test
code is also updated.
This restores some micro-benchmark performance: up to +9% in mmtests mmap1
by my testing +10% to +20% in mmap, mmapaddr, mmapmany tests reported by
Red Hat
Link: https://bugzilla.redhat.com/show_bug.cgi?id=2149636
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam Howlett <[email protected]>
Reported-by: Jirka Hladky <[email protected]>
Suggested-by: Matthew Wilcox (Oracle) <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Add the span to the year of the development.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Cc: Matthew Wilcox <[email protected]>
Cc: Joe Perches <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Along the development cycle, the testing code support for module/in-kernel
compiles was removed. Restore this functionality by moving any internal
API tests to the userspace side, as well as threading tests. Fix the
lockdep issues and add a way to reduce memory usage so the tests can
complete with KASAN + memleak detection. Make the tests work on 32 bit
hosts where possible and detect 32 bit hosts in the radix test suite.
[[email protected]: fix module export]
[[email protected]: fix it some more]
[[email protected]: fix compile warnings on 32bit build in check_find()]
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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This is a test suite that uses the radix test infrastructure. It has been
split into its own commit to allow for easier review of the maple tree
code.
The testing includes:
- Allocation of nodes
- gfp flag allocation checks
- Expansion & contraction of tree
- preallocation checks
- tree navigation by next/prev
- tree navigation by iterators (mas_for_each, etc)
- Number of nodes for a given number of entries
- Generic tree construction tests
- Addition and removal of entries in forward and reverse numerical indexes
- gap searching both forward and reverse
- Combining gaps by overwriting entries in different ways
- splitting right-most node
- splitting left-most node
- overwriting multiple slots
- overwriting across different levels of the tree
- overwriting the middle of a tree
- causing a 3-way split up to the root by overwriting the last slot and
first slot of different nodes and spanning different levels
- RCU stress testing of the tree with threads
- Duplication of the tree by entry count
- Tests which were generated by fuzzers have been added.
- A large number of tests which come from recording crashing in a VM and
reconstructing the tree (see check_erase2_set())
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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maple tree uses lockdep_is_held, so define it as external in the header.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Add support for kmem_cache_free_bulk() and kmem_cache_alloc_bulk() to the
radix tree test suite.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Add functions to get the number of allocations, and total allocations from
a kmem_cache. Also add a function to get the allocated size and a way to
zero the total allocations.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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kmem_cache_set_non_kernel() is a mechanism to allow a certain number of
kmem_cache_alloc requests to succeed even when GFP_KERNEL is not set in
the flags. This functionality allows for testing different paths though
the code.
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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define pr_err to printk
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: David Howells <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: "Matthew Wilcox (Oracle)" <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Sven Schnelle <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Patch series "Introducing the Maple Tree"
The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.
The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.
The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.
The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.
Davidlor said
: Yes I like the maple tree, and at this stage I don't think we can ask for
: more from this series wrt the MM - albeit there seems to still be some
: folks reporting breakage. Fundamentally I see Liam's work to (re)move
: complexity out of the MM (not to say that the actual maple tree is not
: complex) by consolidating the three complimentary data structures very
: much worth it considering performance does not take a hit. This was very
: much a turn off with the range locking approach, which worst case scenario
: incurred in prohibitive overhead. Also as Liam and Matthew have
: mentioned, RCU opens up a lot of nice performance opportunities, and in
: addition academia[1] has shown outstanding scalability of address spaces
: with the foundation of replacing the locked rbtree with RCU aware trees.
A similar work has been discovered in the academic press
https://pdos.csail.mit.edu/papers/rcuvm:asplos12.pdf
Sheer coincidence. We designed our tree with the intention of solving the
hardest problem first. Upon settling on a b-tree variant and a rough
outline, we researched ranged based b-trees and RCU b-trees and did find
that article. So it was nice to find reassurances that we were on the
right path, but our design choice of using ranges made that paper unusable
for us.
This patch (of 70):
The maple tree is an RCU-safe range based B-tree designed to use modern
processor cache efficiently. There are a number of places in the kernel
that a non-overlapping range-based tree would be beneficial, especially
one with a simple interface. If you use an rbtree with other data
structures to improve performance or an interval tree to track
non-overlapping ranges, then this is for you.
The tree has a branching factor of 10 for non-leaf nodes and 16 for leaf
nodes. With the increased branching factor, it is significantly shorter
than the rbtree so it has fewer cache misses. The removal of the linked
list between subsequent entries also reduces the cache misses and the need
to pull in the previous and next VMA during many tree alterations.
The first user that is covered in this patch set is the vm_area_struct,
where three data structures are replaced by the maple tree: the augmented
rbtree, the vma cache, and the linked list of VMAs in the mm_struct. The
long term goal is to reduce or remove the mmap_lock contention.
The plan is to get to the point where we use the maple tree in RCU mode.
Readers will not block for writers. A single write operation will be
allowed at a time. A reader re-walks if stale data is encountered. VMAs
would be RCU enabled and this mode would be entered once multiple tasks
are using the mm_struct.
There is additional BUG_ON() calls added within the tree, most of which
are in debug code. These will be replaced with a WARN_ON() call in the
future. There is also additional BUG_ON() calls within the code which
will also be reduced in number at a later date. These exist to catch
things such as out-of-range accesses which would crash anyways.
Link: https://lkml.kernel.org/r/[email protected]
Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Liam R. Howlett <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Tested-by: David Howells <[email protected]>
Tested-by: Sven Schnelle <[email protected]>
Tested-by: Yu Zhao <[email protected]>
Cc: Vlastimil Babka <[email protected]>
Cc: David Hildenbrand <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Catalin Marinas <[email protected]>
Cc: SeongJae Park <[email protected]>
Cc: Will Deacon <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
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Turn kmem_cache_alloc() into a wrapper around kmem_cache_alloc_lru().
Fixes: 9bbdc0f32409 ("xarray: use kmem_cache_alloc_lru to allocate xa_node")
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Reported-by: Liam R. Howlett <[email protected]>
Reported-by: Li Wang <[email protected]>
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Merge radix-tree definitions from gfp.h and slab.h with these
in tools/lib, so they can be used in other test suites.
Fix style issues in slab.h. Update radix-tree test files.
Signed-off-by: Karolina Drobnik <[email protected]>
Signed-off-by: Mike Rapoport <[email protected]>
Link: https://lore.kernel.org/r/b76ddb8a12fdf9870b55c1401213e44f5e0d0da3.1643796665.git.karolinadrobnik@gmail.com
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Commit 98e1385ef24b ("include/linux/radix-tree.h: replace kernel.h with
the necessary inclusions") broke the radix tree test suite in two
different ways; first by including math.h which didn't exist in the
tools directory, and second by removing an implicit include of
spinlock.h before lockdep.h. Fix both issues.
Cc: Andy Shevchenko <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
Acked-by: Andy Shevchenko <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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Instead of just reporting an assertion failure, report enough information
that we can start diagnosing exactly went wrong.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
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The throbber could race with creation of the anchor entry and cause the
IDR to have zero entries in it, which would cause the test to fail.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
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When run on a single CPU, this test would frequently access already-freed
memory. Due to timing, this bug never showed up on multi-CPU tests.
Reported-by: Chris von Recklinghausen <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
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Several test runners register individual worker threads with the
RCU library, but neglect to register the main thread, which can lead
to objects being freed while the main thread is in what appears to be
an RCU critical section.
Reported-by: Chris von Recklinghausen <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
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Commit 4bba4c4bb09a added tools/include/linux/compiler_types.h which
includes linux/compiler-gcc.h. Unfortunately, we had our own (empty)
compiler_types.h which overrode the one added by that commit, and
so we lost the definition of __must_be_array(). Removing our empty
compiler_types.h fixes the problem and reduces our divergence from the
rest of the tools.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
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If a bitmap needs to be allocated, and then by the time the thread
is scheduled to be run again all the indices which would satisfy the
allocation have been allocated then we would leak the allocation. Almost
impossible to hit in practice, but a trivial fix. Found by Coverity.
Fixes: f32f004cddf8 ("ida: Convert to XArray")
Reported-by: coverity-bot <[email protected]>
Reviewed-by: Kees Cook <[email protected]>
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
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Introducing local_lock broke compilation; fix it all up.
Signed-off-by: Matthew Wilcox (Oracle) <[email protected]>
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git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx
Pull SPDX updates from Greg KH:
"Here are three SPDX patches for 5.7-rc1.
One fixes up the SPDX tag for a single driver, while the other two go
through the tree and add SPDX tags for all of the .gitignore files as
needed.
Nothing too complex, but you will get a merge conflict with your
current tree, that should be trivial to handle (one file modified by
two things, one file deleted.)
All three of these have been in linux-next for a while, with no
reported issues other than the merge conflict"
* tag 'spdx-5.7-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/spdx:
ASoC: MT6660: make spdxcheck.py happy
.gitignore: add SPDX License Identifier
.gitignore: remove too obvious comments
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Add SPDX License Identifier to all .gitignore files.
Signed-off-by: Masahiro Yamada <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
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