rcache: fix deadlock in multi-threaded environments #1673
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This commit fixes several bugs in the registration cache code: - Fix a programming error in the grdma invalidation function that can cause an infinite loop if more than 100 registrations are associated with a munmapped region. This happens because the mca_rcache_base_vma_find_all function returns the same 100 registrations on each call. This has been fixed by adding an iterate function to the vma tree interface. - Always obtain the vma lock when needed. This is required because there may be other threads in the system even if opal_using_threads() is false. Additionally, since it is safe to do so (the vma lock is recursive) the vma interface has been made thread safe. - Avoid calling free() while holding a lock. This avoids race conditions with locks held outside the Open MPI code. Fixes open-mpi#1654. Signed-off-by: Nathan Hjelm <hjelmn@lanl.gov>
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@bosilca Please test. |
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@gpaulsen Please also test. Thanks. |
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@hjelmn so far so good. Not a single deadlock over few tens of runs with large number of threads. I will switch everything to an optimized mode and start an overnight series of tests. I'll update the status tomorrow. |
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👍 |
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This commit fixes several bugs in the registration cache code:
cause an infinite loop if more than 100 registrations are
associated with a munmapped region. This happens because the
mca_rcache_base_vma_find_all function returns the same 100
registrations on each call. This has been fixed by adding an
iterate function to the vma tree interface.
there may be other threads in the system even if
opal_using_threads() is false. Additionally, since it is safe to do
so (the vma lock is recursive) the vma interface has been made
thread safe.
conditions with locks held outside the Open MPI code.
Fixes #1654.
Signed-off-by: Nathan Hjelm hjelmn@lanl.gov