diff --git a/doc/jemalloc.xml.in b/doc/jemalloc.xml.in
index 1e12fd3a..0dcfb98d 100644
--- a/doc/jemalloc.xml.in
+++ b/doc/jemalloc.xml.in
@@ -1055,7 +1055,9 @@ mallctl("arena." STRINGIFY(MALLCTL_ARENAS_ALL) ".decay",
linkend="arena.i.dirty_decay_ms">arena.<i>.dirty_decay_ms
for related dynamic control options. See opt.muzzy_decay_ms
- for a description of muzzy pages.
+ for a description of muzzy pages. Note that when the huge_threshold
+ feature is enabled, the special auto arenas may use its own decay
+ settings.
@@ -1763,10 +1765,11 @@ malloc_conf = "xmalloc:true";]]>
to control allocation for arenas explicitly created via arenas.create such
that all extents originate from an application-supplied extent allocator
- (by specifying the custom extent hook functions during arena creation),
- but the automatically created arenas will have already created extents
- prior to the application having an opportunity to take over extent
- allocation.
+ (by specifying the custom extent hook functions during arena creation).
+ However, the API guarantees for the automatically created arenas may be
+ relaxed -- hooks set there may be called in a "best effort" fashion; in
+ addition there may be extents created prior to the application having an
+ opportunity to take over extent allocation.