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| author | Paul E. McKenney <paulmck@kernel.org> | 2023-03-24 19:05:50 +0300 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2023-04-04 18:36:43 +0300 |
| commit | a7bf4d7c16c1cf9753873879630a5d5169eb3206 (patch) | |
| tree | af06eeafeb3848e5b55fcb641187121c90d387f3 /kernel/rcu | |
| parent | fd1b3f8e097b7fbbab8ac4a802b24fc23c703dcf (diff) | |
| download | linux-a7bf4d7c16c1cf9753873879630a5d5169eb3206.tar.xz | |
srcu: Check for readers at module-exit time
If a given statically allocated in-module srcu_struct structure was ever
used for updates, srcu_module_going() will invoke cleanup_srcu_struct()
at module-exit time. This will check for the error case of SRCU readers
persisting past module-exit time. On the other hand, if this srcu_struct
structure never went through a grace period, srcu_module_going() only
invokes free_percpu(), which would result in strange failures if SRCU
readers persisted past module-exit time.
This commit therefore adds a srcu_readers_active() check to
srcu_module_going(), splatting if readers have persisted and refraining
from invoking free_percpu() in that case. Better to leak memory than
to suffer silent memory corruption!
[ paulmck: Apply Zhang, Qiang1 feedback on memory leak. ]
Tested-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/srcutree.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 169a6513b739..f9dd6ed5503e 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -1911,7 +1911,8 @@ static void srcu_module_going(struct module *mod) if (!rcu_seq_state(smp_load_acquire(&ssp->srcu_sup->srcu_gp_seq_needed)) && !WARN_ON_ONCE(!ssp->srcu_sup->sda_is_static)) cleanup_srcu_struct(ssp); - free_percpu(ssp->sda); + if (!WARN_ON(srcu_readers_active(ssp))) + free_percpu(ssp->sda); } } |