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89b01913dc
In the case we trigger dlm_free_rsb() that does a call_rcu() and the
responding kfree() of res_lvbptr and a kmem_cache_free() of the rsb
pointer we need to wait until this pending operation is done before
calling kmem_cache_destroy(). We doing that by using rcu_barrier() that
waits until all pending call_rcu() are done. This avoids that
kmem_cache_destroy() complains about active objects around that are not
being freed yet by call_rcu().
There is currently more discussions about to make this behaviour better,
see:
https://lore.kernel.org/netdev/20240609082726.32742-1-Julia.Lawall@inria.fr/
However this is only for call_rcu() if the callback calls
kmem_cache_destroy() only to replace it by kfree_rcu() call which has
currently some issue. This isn't our case because we also free the
res_lvbptr if being set.
For our case, to avoid the above race rcu_barrier() should be used before
calling kmem_cache_destroy() to be sure that there are no active objects
around. This is exactly what net/batman-adv is also doing before calling their
kmem_cache_destroy() in module unloading.
Fixes: 01fdeca1cc ("dlm: use rcu to avoid an extra rsb struct lookup")
Signed-off-by: Alexander Aring <aahringo@redhat.com>
Signed-off-by: David Teigland <teigland@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
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Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.