X-Git-Url: http://git.liburcu.org/?p=userspace-rcu.git;a=blobdiff_plain;f=README;h=97fba69462cc6e862578b942715316d40dfedecb;hp=ce25e3a3dabc8977f7a4dc5d4e391e5238e455fc;hb=073b42da0335223bc1b83105e4b169181f792097;hpb=483c853e4227f9d0b3ad03f7a4bd8038fe26da89

diff --git a/README b/README
index ce25e3a..97fba69 100644
--- a/README
+++ b/README
@@ -253,3 +253,17 @@ Interaction with fork()
 	call_rcu_after_fork_parent() after the fork().  The child
 	process must invoke call_rcu_after_fork_child().
 	These three APIs are suitable for passing to pthread_atfork().
+	Even though these three APIs are suitable for passing to
+	pthread_atfork(), use of pthread_atfork() is *STRONGLY
+	DISCOURAGED* for programs calling the glibc memory allocator
+	(malloc(), calloc(), free(), ...) within call_rcu callbacks.
+	This is due to limitations in the way glibc memory allocator
+	handles calls to the memory allocator from concurrent threads
+	while the pthread_atfork() handlers are executing.
+	Combining e.g.:
+	* call to free() from callbacks executed within call_rcu worker
+	  threads,
+	* executing call_rcu atfork handlers within the glibc pthread
+	  atfork mechanism,
+	will sometimes trigger interesting process hangs. This usually
+	hangs on a memory allocator lock within glibc.