Downstream-only patch to disable rseq by default.  This is necessary
because CRIU does not yet support rseq:

  criu: Implement rseq support
  <https://bugzilla.redhat.com/show_bug.cgi?id=2033446>

diff --git a/manual/tunables.texi b/manual/tunables.texi
index 28ff502990c2a10f..f559c44dcec4624b 100644
--- a/manual/tunables.texi
+++ b/manual/tunables.texi
@@ -425,11 +425,13 @@ The value is measured in bytes.  The default is @samp{41943040}
 @end deftp
 
 @deftp Tunable glibc.pthread.rseq
-The @code{glibc.pthread.rseq} tunable can be set to @samp{0}, to disable
-restartable sequences support in @theglibc{}.  This enables applications
-to perform direct restartable sequence registration with the kernel.
-The default is @samp{1}, which means that @theglibc{} performs
-registration on behalf of the application.
+The @code{glibc.pthread.rseq} tunable can be set to @samp{1}, to enable
+restartable sequences support.  @Theglibc{} uses this to optimize the
+@code{sched_getcpu} function.
+
+The default is @samp{0}, which means that applications can perform
+restartable sequences registration, but @code{sched_getcpu} is not
+accelerated.
 
 Restartable sequences are a Linux-specific extension.
 @end deftp
diff --git a/sysdeps/nptl/dl-tunables.list b/sysdeps/nptl/dl-tunables.list
index d24f4be0d08ba407..df2a39ce01858d3b 100644
--- a/sysdeps/nptl/dl-tunables.list
+++ b/sysdeps/nptl/dl-tunables.list
@@ -31,7 +31,7 @@ glibc {
       type: INT_32
       minval: 0
       maxval: 1
-      default: 1
+      default: 0
     }
   }
 }