diff options
| author | Uladzislau Rezki (Sony) <urezki@gmail.com> | 2023-04-04 16:13:00 +0200 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2023-05-09 17:26:21 -0700 |
| commit | f32276a37652a9ce05db27cdfb40ac3e3fc98f9f (patch) | |
| tree | a111e1d34cb2a7e9b7a2c63d10ae421712535992 /kernel/rcu | |
| parent | cdfa0f6fa6b7183c062046043b649b9a91e3ac52 (diff) | |
rcu/kvfree: Add debug check for GP complete for kfree_rcu_cpu list
Under low-memory conditions, kvfree_rcu() will use each object's
rcu_head structure to queue objects in a singly linked list headed by
the kfree_rcu_cpu structure's ->head field. This list is passed to
call_rcu() as a unit, but there is no indication of which grace period
this list needs to wait for. This in turn prevents adding debug checks
in the kfree_rcu_work() as was done for the two page-of-pointers channels
in the kfree_rcu_cpu structure.
This commit therefore adds a ->head_free_gp_snap field to the
kfree_rcu_cpu_work structure to record this grace-period number. It also
adds a WARN_ON_ONCE() to kfree_rcu_monitor() that checks to make sure
that the required grace period has in fact elapsed.
[ paulmck: Fix kerneldoc issue raised by Stephen Rothwell. ]
Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 91d75fd6c579..7452ba97ba34 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2773,6 +2773,7 @@ struct kvfree_rcu_bulk_data { * struct kfree_rcu_cpu_work - single batch of kfree_rcu() requests * @rcu_work: Let queue_rcu_work() invoke workqueue handler after grace period * @head_free: List of kfree_rcu() objects waiting for a grace period + * @head_free_gp_snap: Grace-period snapshot to check for attempted premature frees. * @bulk_head_free: Bulk-List of kvfree_rcu() objects waiting for a grace period * @krcp: Pointer to @kfree_rcu_cpu structure */ @@ -2780,6 +2781,7 @@ struct kvfree_rcu_bulk_data { struct kfree_rcu_cpu_work { struct rcu_work rcu_work; struct rcu_head *head_free; + struct rcu_gp_oldstate head_free_gp_snap; struct list_head bulk_head_free[FREE_N_CHANNELS]; struct kfree_rcu_cpu *krcp; }; @@ -2985,6 +2987,7 @@ static void kfree_rcu_work(struct work_struct *work) struct rcu_head *head; struct kfree_rcu_cpu *krcp; struct kfree_rcu_cpu_work *krwp; + struct rcu_gp_oldstate head_gp_snap; int i; krwp = container_of(to_rcu_work(work), @@ -2999,6 +3002,7 @@ static void kfree_rcu_work(struct work_struct *work) // Channel 3. head = krwp->head_free; krwp->head_free = NULL; + head_gp_snap = krwp->head_free_gp_snap; raw_spin_unlock_irqrestore(&krcp->lock, flags); // Handle the first two channels. @@ -3015,7 +3019,8 @@ static void kfree_rcu_work(struct work_struct *work) * queued on a linked list through their rcu_head structures. * This list is named "Channel 3". */ - kvfree_rcu_list(head); + if (head && !WARN_ON_ONCE(!poll_state_synchronize_rcu_full(&head_gp_snap))) + kvfree_rcu_list(head); } static bool @@ -3147,6 +3152,7 @@ static void kfree_rcu_monitor(struct work_struct *work) // objects queued on the linked list. if (!krwp->head_free) { krwp->head_free = krcp->head; + get_state_synchronize_rcu_full(&krwp->head_free_gp_snap); atomic_set(&krcp->head_count, 0); WRITE_ONCE(krcp->head, NULL); } |