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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:
|
||
|---|---|---|
| .. | ||
| hmat.c | ||
| Kconfig | ||
| Makefile | ||
| srat.c | ||