diff options
| author | Maxim Levitsky <mlevitsk@redhat.com> | 2025-05-12 14:04:03 -0400 |
|---|---|---|
| committer | Paolo Bonzini <pbonzini@redhat.com> | 2025-05-27 12:16:41 -0400 |
| commit | fb49f07ba1d9d8c9bd8854878ae6b5b21ff9ac45 (patch) | |
| tree | 62d4f79d9b829d884245ee9187a1c905201866e9 /kernel/locking/mutex.c | |
| parent | c5b6ababd21ab6bb251e5a2b4db110e76fb00a26 (diff) | |
locking/mutex: implement mutex_lock_killable_nest_lock
KVM's SEV intra-host migration code needs to lock all vCPUs
of the source and the target VM, before it proceeds with the migration.
The number of vCPUs that belong to each VM is not bounded by anything
except a self-imposed KVM limit of CONFIG_KVM_MAX_NR_VCPUS vCPUs which is
significantly larger than the depth of lockdep's lock stack.
Luckily, the locks in both of the cases mentioned above, are held under
the 'kvm->lock' of each VM, which means that we can use the little
known lockdep feature called a "nest_lock" to support this use case in
a cleaner way, compared to the way it's currently done.
Implement and expose 'mutex_lock_killable_nest_lock' for this
purpose.
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Message-ID: <20250512180407.659015-3-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'kernel/locking/mutex.c')
| -rw-r--r-- | kernel/locking/mutex.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c index c75a838d3bae..234923121ff0 100644 --- a/kernel/locking/mutex.c +++ b/kernel/locking/mutex.c @@ -808,11 +808,12 @@ _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest) EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock); int __sched -mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass) +_mutex_lock_killable(struct mutex *lock, unsigned int subclass, + struct lockdep_map *nest) { - return __mutex_lock(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_); + return __mutex_lock(lock, TASK_KILLABLE, subclass, nest, _RET_IP_); } -EXPORT_SYMBOL_GPL(mutex_lock_killable_nested); +EXPORT_SYMBOL_GPL(_mutex_lock_killable); int __sched mutex_lock_interruptible_nested(struct mutex *lock, unsigned int subclass) |