On 11 September 2026 08:21:25 BST, Kunwu Chan <[email protected]> wrote:
Better late than never. >Atomic SRCU must remain in the small size state. Warn if this >invariant is violated and avoid transitioning to big in that case. Fair enough. Reviewed-by: Bradley Morgan <[email protected]> > >Signed-off-by: Kunwu Chan <[email protected]> >--- >Changes since v2: >- Also prevent the transition when the atomic SRCU size-state > invariant is violated, per Paul McKenney's suggestion. >-v2: https://lore.kernel.org/rcu/[email protected]/ > >Changes since v1: >- Drop the !is_atomic guard from v1 and add WARN_ON_ONCE() instead, > per Paul McKenney's suggestion. >- v1: >https://lore.kernel.org/rcu/[email protected]/ >--- > kernel/rcu/srcutree.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > >diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c >index 84c022ec8e09..07db4e459b30 100644 >--- a/kernel/rcu/srcutree.c >+++ b/kernel/rcu/srcutree.c >@@ -1073,8 +1073,11 @@ static void srcu_gp_end(struct srcu_struct *ssp, bool >is_atomic) > raw_spin_unlock_irq_rcu_node(sup); > } > >- /* Transition to big if needed. */ >- if (ss_state != SRCU_SIZE_SMALL && ss_state != SRCU_SIZE_BIG) { >+ /* Transition to big if needed, but never for atomic SRCU. */ >+ if (ssp->srcu_reader_flavor == SRCU_READ_FLAVOR_ATOMIC && >+ ss_state != SRCU_SIZE_SMALL) { >+ WARN_ON_ONCE(1); >+ } else if (ss_state != SRCU_SIZE_SMALL && ss_state != SRCU_SIZE_BIG) { I like this fix. > if (ss_state == SRCU_SIZE_ALLOC) > init_srcu_struct_nodes(ssp, GFP_KERNEL); > else > --- Thanks! https://lore.kernel.org/all/[email protected]/
