diff options
| author | Dave Jiang <dave.jiang@intel.com> | 2025-11-05 16:51:15 -0700 |
|---|---|---|
| committer | Dave Jiang <dave.jiang@intel.com> | 2025-11-12 14:47:55 -0700 |
| commit | 214291cbaaceeb28debd773336642b1fca393ae0 (patch) | |
| tree | 529cf624adf7646d17cf0bc47d1d7623d0f58c70 /drivers | |
| parent | b6cfddd26ec55e865b4715f73e9bbb17a15091ed (diff) | |
| download | net-214291cbaaceeb28debd773336642b1fca393ae0.tar.gz | |
acpi/hmat: Fix lockdep warning for hmem_register_resource()
The following lockdep splat was observed while kernel auto-online a CXL
memory region:
======================================================
WARNING: possible circular locking dependency detected
6.17.0djtest+ #53 Tainted: G W
------------------------------------------------------
systemd-udevd/3334 is trying to acquire lock:
ffffffff90346188 (hmem_resource_lock){+.+.}-{4:4}, at: hmem_register_resource+0x31/0x50
but task is already holding lock:
ffffffff90338890 ((node_chain).rwsem){++++}-{4:4}, at: blocking_notifier_call_chain+0x2e/0x70
which lock already depends on the new lock.
[..]
Chain exists of:
hmem_resource_lock --> mem_hotplug_lock --> (node_chain).rwsem
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
rlock((node_chain).rwsem);
lock(mem_hotplug_lock);
lock((node_chain).rwsem);
lock(hmem_resource_lock);
The lock ordering can cause potential deadlock. There are instances
where hmem_resource_lock is taken after (node_chain).rwsem, and vice
versa.
Split out the target update section of hmat_register_target() so that
hmat_callback() only envokes that section instead of attempt to register
hmem devices that it does not need to.
[ dj: Fix up comment to be closer to 80cols. (Jonathan) ]
Fixes: cf8741ac57ed ("ACPI: NUMA: HMAT: Register "soft reserved" memory as an "hmem" device")
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Tested-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Reviewed-by: Smita Koralahalli <Smita.KoralahalliChannabasappa@amd.com>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20251105235115.85062-3-dave.jiang@intel.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/acpi/numa/hmat.c | 46 |
1 files changed, 25 insertions, 21 deletions
diff --git a/drivers/acpi/numa/hmat.c b/drivers/acpi/numa/hmat.c index 5a36d57289b43d..11e4483685c9cf 100644 --- a/drivers/acpi/numa/hmat.c +++ b/drivers/acpi/numa/hmat.c @@ -874,11 +874,33 @@ static void hmat_register_target_devices(struct memory_target *target) } } -static void hmat_register_target(struct memory_target *target) +static void hmat_hotplug_target(struct memory_target *target) { int nid = pxm_to_node(target->memory_pxm); /* + * Skip offline nodes. This can happen when memory marked EFI_MEMORY_SP, + * "specific purpose", is applied to all the memory in a proximity + * domain leading to * the node being marked offline / unplugged, or if + * memory-only "hotplug" node is offline. + */ + if (nid == NUMA_NO_NODE || !node_online(nid)) + return; + + guard(mutex)(&target_lock); + if (target->registered) + return; + + hmat_register_target_initiators(target); + hmat_register_target_cache(target); + hmat_register_target_perf(target, ACCESS_COORDINATE_LOCAL); + hmat_register_target_perf(target, ACCESS_COORDINATE_CPU); + target->registered = true; +} + +static void hmat_register_target(struct memory_target *target) +{ + /* * Devices may belong to either an offline or online * node, so unconditionally add them. */ @@ -895,25 +917,7 @@ static void hmat_register_target(struct memory_target *target) } mutex_unlock(&target_lock); - /* - * Skip offline nodes. This can happen when memory - * marked EFI_MEMORY_SP, "specific purpose", is applied - * to all the memory in a proximity domain leading to - * the node being marked offline / unplugged, or if - * memory-only "hotplug" node is offline. - */ - if (nid == NUMA_NO_NODE || !node_online(nid)) - return; - - mutex_lock(&target_lock); - if (!target->registered) { - hmat_register_target_initiators(target); - hmat_register_target_cache(target); - hmat_register_target_perf(target, ACCESS_COORDINATE_LOCAL); - hmat_register_target_perf(target, ACCESS_COORDINATE_CPU); - target->registered = true; - } - mutex_unlock(&target_lock); + hmat_hotplug_target(target); } static void hmat_register_targets(void) @@ -939,7 +943,7 @@ static int hmat_callback(struct notifier_block *self, if (!target) return NOTIFY_OK; - hmat_register_target(target); + hmat_hotplug_target(target); return NOTIFY_OK; } |