There's a relatively rare race where we look at the per-cpu preallocated
IDA bitmap, see it's NULL, allocate a new one, and atomically update it.
If the kmalloc() happened to sleep and we were rescheduled to a different
CPU, or an interrupt came in at the exact right time, another task
might have successfully allocated a bitmap and already deposited it.
I forgot what the semantics of cmpxchg() were and ended up freeing the
wrong bitmap leading to KASAN reporting a use-after-free.
Dmitry found the bug with syzkaller & wrote the patch. I wrote the test
case that will reproduce the bug without his patch being applied.
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
If the -l flag is set, run the tests for 100 seconds each instead of
the normal 10 seconds.
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Rehas Sachdeva <aquannie@gmail.com>
Make the output of radix tree test suite less verbose by default and add
-v and -vv command line options for increasing level of verbosity.
Signed-off-by: Rehas Sachdeva <aquannie@gmail.com>
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
The IDR is very similar to the radix tree. It has some functionality that
the radix tree did not have (alloc next free, cyclic allocation, a
callback-based for_each, destroy tree), which is readily implementable on
top of the radix tree. A few small changes were needed in order to use a
tag to represent nodes with free space below them. More extensive
changes were needed to support storing NULL as a valid entry in an IDR.
Plain radix trees still interpret NULL as a not-present entry.
The IDA is reimplemented as a client of the newly enhanced radix tree. As
in the current implementation, it uses a bitmap at the last level of the
tree.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Matthew Wilcox <mawilcox@microsoft.com>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This is an exceptionally complicated function with just one caller
(tag_pages_for_writeback). We devote a large portion of the runtime of
the test suite to testing this one function which has one caller. By
introducing the new function radix_tree_iter_tag_set(), we can eliminate
all of the complexity while keeping the performance. The caller can now
use a fairly standard radix_tree_for_each() loop, and it doesn't need to
worry about tricksy things like 'start' wrapping.
The test suite continues to spend a large amount of time investigating
this function, but now it's testing the underlying primitives such as
radix_tree_iter_resume() and the radix_tree_for_each_tagged() iterator
which are also used by other parts of the kernel.
Link: http://lkml.kernel.org/r/1480369871-5271-57-git-send-email-mawilcox@linuxonhyperv.com
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Matthew Wilcox <mawilcox@microsoft.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There are four cases I can see where we could end up with a NULL 'slot' in
radix_tree_next_slot(). This unit test exercises all four of them, making
sure that if in the future we have an unsafe path through
radix_tree_next_slot(), we'll catch it.
Here are details on the four cases:
1) radix_tree_iter_retry() via a non-tagged iteration like
radix_tree_for_each_slot(). In this case we currently aren't seeing a bug
because radix_tree_iter_retry() sets
iter->next_index = iter->index;
which means that in in the else case in radix_tree_next_slot(), 'count' is
zero, so we skip over the while() loop and effectively just return NULL
without ever dereferencing 'slot'.
2) radix_tree_iter_retry() via tagged iteration like
radix_tree_for_each_tagged(). This case was giving us NULL pointer
dereferences in testing, and was fixed with this commit:
commit 3cb9185c67 ("radix-tree: fix radix_tree_iter_retry() for tagged
iterators.")
This fix doesn't explicitly check for 'slot' being NULL, though, it works
around the NULL pointer dereference by instead zeroing iter->tags in
radix_tree_iter_retry(), which makes us bail out of the if() case in
radix_tree_next_slot() before we dereference 'slot'.
3) radix_tree_iter_next() via via a non-tagged iteration like
radix_tree_for_each_slot(). This currently happens in shmem_tag_pins()
and shmem_partial_swap_usage().
As with non-tagged iteration, 'count' in the else case of
radix_tree_next_slot() is zero, so we skip over the while() loop and
effectively just return NULL without ever dereferencing 'slot'.
4) radix_tree_iter_next() via tagged iteration like
radix_tree_for_each_tagged(). This happens in shmem_wait_for_pins().
radix_tree_iter_next() zeros out iter->tags, so we end up exiting
radix_tree_next_slot() here:
if (flags & RADIX_TREE_ITER_TAGGED) {
void *canon = slot;
iter->tags >>= 1;
if (unlikely(!iter->tags))
return NULL;
Link: http://lkml.kernel.org/r/20160815194237.25967-3-ross.zwisler@linux.intel.com
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Test suite infrastructure for working with multiorder entries.
The test itself is pretty basic: Add an entry, check that all expected
indices return that entry and that indices around that entry don't
return an entry. Then delete the entry and check no index returns that
entry. Tests a few edge conditions including the multiorder entry at
index 0 and at a higher index. Also tests deleting through an alias as
well as through the canonical index.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Reviewed-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently the full suite of regression tests take upwards of 30 minutes
to run on my development machine. The vast majority of this time is
taken by the big_gang_check() and copy_tag_check() tests, which each run
their tests through thousands of iterations...does this have value?
Without big_gang_check() and copy_tag_check(), the test suite runs in
around 15 seconds on my box.
Honestly the first time I ever ran through the entire test suite was to
gather the timings for this email - it simply takes too long to be
useful on a normal basis.
Instead, hide the excessive iterations through big_gang_check() and
copy_tag_check() tests behind an '-l' flag (for "long run") in case they
are still useful, but allow the regression test suite to complete in a
reasonable amount of time. We still run each of these tests a few times
(3 at present) to try and keep the test coverage.
Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Kirill Shutemov <kirill.shutemov@linux.intel.com>
Cc: Jan Kara <jack@suse.com>
Cc: Neil Brown <neilb@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After calling radix_tree_iter_retry(), 'slot' will be set to NULL. This
can cause radix_tree_next_slot() to dereference the NULL pointer. Add
Konstantin Khlebnikov's test to the regression framework.
Signed-off-by: Matthew Wilcox <matthew.r.wilcox@intel.com>
Reported-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This code is mostly from Andrew Morton and Nick Piggin; tarball downloaded
from http://ozlabs.org/~akpm/rtth.tar.gz with sha1sum
0ce679db9ec047296b5d1ff7a1dfaa03a7bef1bd
Some small modifications were necessary to the test harness to fix the
build with the current Linux source code.
I also made minor modifications to automatically test the radix-tree.c
and radix-tree.h files that are in the current source tree, as opposed
to a copied and slightly modified version. I am sure more could be done
to tidy up the harness, as well as adding more tests.
[koct9i@gmail.com: fix compilation]
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
Cc: Shuah Khan <shuahkh@osg.samsung.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@linux.intel.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
