srcu: Push srcu_node allocation to GP when non-preemptible

Browse source

When the srcutree.convert_to_big and srcutree.big_cpu_lim kernel boot
parameters specify initialization-time allocation of the srcu_node
tree for statically allocated srcu_struct structures (for example, in
DEFINE_SRCU() at build time instead of init_srcu_struct() at runtime),
init_srcu_struct_nodes() will attempt to dynamically allocate this tree
at the first run-time update-side use of this srcu_struct structure,
but while holding a raw spinlock.  Because the memory allocator can
acquire non-raw spinlocks, this can result in lockdep splats.

This commit therefore uses the same SRCU_SIZE_ALLOC trick that is used
when the first run-time update-side use of this srcu_struct structure
happens before srcu_init() is called.  The actual allocation then takes
place from workqueue context at the ends of upcoming SRCU grace periods.

[boqun: Adjust the sha1 of the Fixes tag]

Fixes: 175b45ed34 ("srcu: Use raw spinlocks so call_srcu() can be used under preempt_disable()")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Boqun Feng <boqun@kernel.org>

...

This commit is contained in:

Paul E. McKenney 2026-03-20 20:29:20 -07:00 • committed by Boqun Feng

parent 175b45ed34

commit 61bbcfb505

1 changed files with 5 additions and 2 deletions

Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL

Download patch file Download diff file Expand all files Collapse all files

7

kernel/rcu/srcutree.c

View file