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| author | Zqiang <qiang.zhang1211@gmail.com> | 2024-01-10 16:11:28 +0800 |
|---|---|---|
| committer | Boqun Feng <boqun.feng@gmail.com> | 2024-02-14 07:50:45 -0800 |
| commit | dda98810b552fc6bf650f4270edeebdc2f28bd3f (patch) | |
| tree | 3acbb5b037a6dd14810e8f3c3a0abcc520b0cfe0 /kernel/rcu | |
| parent | afd4e6964745ed98b74cacdcce21d73280a0a253 (diff) | |
| download | linux-dda98810b552fc6bf650f4270edeebdc2f28bd3f.tar.gz linux-dda98810b552fc6bf650f4270edeebdc2f28bd3f.tar.bz2 linux-dda98810b552fc6bf650f4270edeebdc2f28bd3f.zip | |
rcu/nocb: Fix WARN_ON_ONCE() in the rcu_nocb_bypass_lock()
For the kernels built with CONFIG_RCU_NOCB_CPU_DEFAULT_ALL=y and
CONFIG_RCU_LAZY=y, the following scenarios will trigger WARN_ON_ONCE()
in the rcu_nocb_bypass_lock() and rcu_nocb_wait_contended() functions:
CPU2 CPU11
kthread
rcu_nocb_cb_kthread ksys_write
rcu_do_batch vfs_write
rcu_torture_timer_cb proc_sys_write
__kmem_cache_free proc_sys_call_handler
kmemleak_free drop_caches_sysctl_handler
delete_object_full drop_slab
__delete_object shrink_slab
put_object lazy_rcu_shrink_scan
call_rcu rcu_nocb_flush_bypass
__call_rcu_commn rcu_nocb_bypass_lock
raw_spin_trylock(&rdp->nocb_bypass_lock) fail
atomic_inc(&rdp->nocb_lock_contended);
rcu_nocb_wait_contended WARN_ON_ONCE(smp_processor_id() != rdp->cpu);
WARN_ON_ONCE(atomic_read(&rdp->nocb_lock_contended)) |
|_ _ _ _ _ _ _ _ _ _same rdp and rdp->cpu != 11_ _ _ _ _ _ _ _ _ __|
Reproduce this bug with "echo 3 > /proc/sys/vm/drop_caches".
This commit therefore uses rcu_nocb_try_flush_bypass() instead of
rcu_nocb_flush_bypass() in lazy_rcu_shrink_scan(). If the nocb_bypass
queue is being flushed, then rcu_nocb_try_flush_bypass will return
directly.
Signed-off-by: Zqiang <qiang.zhang1211@gmail.com>
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun.feng@gmail.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree_nocb.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index 9e8052ba14b9..ffa69a5e18f4 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1391,7 +1391,7 @@ lazy_rcu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) rcu_nocb_unlock_irqrestore(rdp, flags); continue; } - WARN_ON_ONCE(!rcu_nocb_flush_bypass(rdp, NULL, jiffies, false)); + rcu_nocb_try_flush_bypass(rdp, jiffies); rcu_nocb_unlock_irqrestore(rdp, flags); wake_nocb_gp(rdp, false); sc->nr_to_scan -= _count; |