KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/Documentation/admin-guide/sysctl/sunrpc.rst b/Documentation/admin-guide/sysctl/sunrpc.rst
new file mode 100644
index 000000000..09780a682
--- /dev/null
+++ b/Documentation/admin-guide/sysctl/sunrpc.rst
@@ -0,0 +1,25 @@
+===================================
+Documentation for /proc/sys/sunrpc/
+===================================
+
+kernel version 2.2.10
+
+Copyright (c) 1998, 1999,  Rik van Riel <riel@nl.linux.org>
+
+For general info and legal blurb, please look in index.rst.
+
+------------------------------------------------------------------------------
+
+This file contains the documentation for the sysctl files in
+/proc/sys/sunrpc and is valid for Linux kernel version 2.2.
+
+The files in this directory can be used to (re)set the debug
+flags of the SUN Remote Procedure Call (RPC) subsystem in
+the Linux kernel. This stuff is used for NFS, KNFSD and
+maybe a few other things as well.
+
+The files in there are used to control the debugging flags:
+rpc_debug, nfs_debug, nfsd_debug and nlm_debug.
+
+These flags are for kernel hackers only. You should read the
+source code in net/sunrpc/ for more information.