diff --git a/include/asm-generic/qspinlock.h b/include/asm-generic/qspinlock.h
index d74b13825501..995513fa2690 100644
--- a/include/asm-generic/qspinlock.h
+++ b/include/asm-generic/qspinlock.h
@@ -2,6 +2,35 @@
 /*
  * Queued spinlock
  *
+ * A 'generic' spinlock implementation that is based on MCS locks. For an
+ * architecture that's looking for a 'generic' spinlock, please first consider
+ * ticket-lock.h and only come looking here when you've considered all the
+ * constraints below and can show your hardware does actually perform better
+ * with qspinlock.
+ *
+ * qspinlock relies on atomic_*_release()/atomic_*_acquire() to be RCsc (or no
+ * weaker than RCtso if you're power), where regular code only expects atomic_t
+ * to be RCpc.
+ *
+ * qspinlock relies on a far greater (compared to asm-generic/spinlock.h) set
+ * of atomic operations to behave well together, please audit them carefully to
+ * ensure they all have forward progress. Many atomic operations may default to
+ * cmpxchg() loops which will not have good forward progress properties on
+ * LL/SC architectures.
+ *
+ * One notable example is atomic_fetch_or_acquire(), which x86 cannot (cheaply)
+ * do. Carefully read the patches that introduced
+ * queued_fetch_set_pending_acquire().
+ *
+ * qspinlock also heavily relies on mixed size atomic operations, in specific
+ * it requires architectures to have xchg16; something which many LL/SC
+ * architectures need to implement as a 32bit and+or in order to satisfy the
+ * forward progress guarantees mentioned above.
+ *
+ * Further reading on mixed size atomics that might be relevant:
+ *
+ *   http://www.cl.cam.ac.uk/~pes20/popl17/mixed-size.pdf
+ *
  * (C) Copyright 2013-2015 Hewlett-Packard Development Company, L.P.
  * (C) Copyright 2015 Hewlett-Packard Enterprise Development LP
  *