mm/slab: use call_rcu() in unknown context if irqs are enabled

Browse source

call_rcu() disables IRQs with local_irq_save() to protect its per-cpu
data structures. Therefore, if IRQs are not disabled, they cannot be
corrupted by reentrance into call_rcu(). So fall back to the deferred
path only when !allow_spin && irqs_disabled().

The RCU subsystem does not guarantee this contractually, and this
optimization relies on RCU's implementation details. Ideally, it should
be removed once call_rcu_nolock() is supported by the RCU subsystem.

Link: https://lore.kernel.org/linux-mm/CAADnVQKRVD5ZSnEKbZZU7w86gHbGHUug2pvzpgZTngNS+fg4rw@mail.gmail.com
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Harry Yoo (Oracle) <harry@kernel.org>
Link: https://patch.msgid.link/20260729-kfree_rcu_nolock-v5-3-a28cdcda9673@kernel.org
Reviewed-by: Shengming Hu <hu.shengming@zte.com.cn>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

...

This commit is contained in:

Harry Yoo (Oracle) 2026-07-29 17:20:11 +09:00 • committed by Vlastimil Babka (SUSE)

parent f3521fbec2

commit f8e0c30599

1 changed files with 6 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

8

mm/slub.c

View file