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>

8 files changed, 458 insertions, 0 deletions

diff --git a/tools/testing/selftests/zram/.gitignore b/tools/testing/selftests/zram/.gitignore
new file mode 100644
index 000000000..088cd9bad
--- /dev/null
+++ b/tools/testing/selftests/zram/.gitignore
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+err.log
diff --git a/tools/testing/selftests/zram/Makefile b/tools/testing/selftests/zram/Makefile
new file mode 100644
index 000000000..7f78eb1b5
--- /dev/null
+++ b/tools/testing/selftests/zram/Makefile
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-2.0
+all:
+
+TEST_PROGS := zram.sh
+TEST_FILES := zram01.sh zram02.sh zram_lib.sh
+EXTRA_CLEAN := err.log
+
+include ../lib.mk
+
diff --git a/tools/testing/selftests/zram/README b/tools/testing/selftests/zram/README
new file mode 100644
index 000000000..82921c756
--- /dev/null
+++ b/tools/testing/selftests/zram/README
@@ -0,0 +1,39 @@
+zram: Compressed RAM based block devices
+----------------------------------------
+* Introduction
+
+The zram module creates RAM based block devices named /dev/zram<id>
+(<id> = 0, 1, ...). Pages written to these disks are compressed and stored
+in memory itself. These disks allow very fast I/O and compression provides
+good amounts of memory savings. Some of the usecases include /tmp storage,
+use as swap disks, various caches under /var and maybe many more :)
+
+Statistics for individual zram devices are exported through sysfs nodes at
+/sys/block/zram<id>/
+
+Kconfig required:
+CONFIG_ZRAM=y
+CONFIG_CRYPTO_LZ4=y
+CONFIG_ZSMALLOC=y
+
+ZRAM Testcases
+--------------
+zram_lib.sh: create library with initialization/cleanup functions
+zram.sh: For sanity check of CONFIG_ZRAM and to run zram01 and zram02
+
+Two functional tests: zram01 and zram02:
+zram01.sh: creates general purpose ram disks with ext4 filesystems
+zram02.sh: creates block device for swap
+
+Commands required for testing:
+ - bc
+ - dd
+ - free
+ - awk
+ - mkswap
+ - swapon
+ - swapoff
+ - mkfs/ mkfs.ext4
+
+For more information please refer:
+kernel-source-tree/Documentation/admin-guide/blockdev/zram.rst
diff --git a/tools/testing/selftests/zram/config b/tools/testing/selftests/zram/config
new file mode 100644
index 000000000..e0cc47e2c
--- /dev/null
+++ b/tools/testing/selftests/zram/config
@@ -0,0 +1,2 @@
+CONFIG_ZSMALLOC=y
+CONFIG_ZRAM=m
diff --git a/tools/testing/selftests/zram/zram.sh b/tools/testing/selftests/zram/zram.sh
new file mode 100755
index 000000000..b0b91d9b0
--- /dev/null
+++ b/tools/testing/selftests/zram/zram.sh
@@ -0,0 +1,18 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0
+TCID="zram.sh"
+
+. ./zram_lib.sh
+
+run_zram () {
+echo "--------------------"
+echo "running zram tests"
+echo "--------------------"
+./zram01.sh
+echo ""
+./zram02.sh
+}
+
+check_prereqs
+
+run_zram
diff --git a/tools/testing/selftests/zram/zram01.sh b/tools/testing/selftests/zram/zram01.sh
new file mode 100755
index 000000000..8f4affe34
--- /dev/null
+++ b/tools/testing/selftests/zram/zram01.sh
@@ -0,0 +1,75 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2015 Oracle and/or its affiliates. All Rights Reserved.
+#
+# Test creates several zram devices with different filesystems on them.
+# It fills each device with zeros and checks that compression works.
+#
+# Author: Alexey Kodanev <alexey.kodanev@oracle.com>
+# Modified: Naresh Kamboju <naresh.kamboju@linaro.org>
+
+TCID="zram01"
+ERR_CODE=0
+
+. ./zram_lib.sh
+
+# Test will create the following number of zram devices:
+dev_num=1
+# This is a list of parameters for zram devices.
+# Number of items must be equal to 'dev_num' parameter.
+zram_max_streams="2"
+
+# The zram sysfs node 'disksize' value can be either in bytes,
+# or you can use mem suffixes. But in some old kernels, mem
+# suffixes are not supported, for example, in RHEL6.6GA's kernel
+# layer, it uses strict_strtoull() to parse disksize which does
+# not support mem suffixes, in some newer kernels, they use
+# memparse() which supports mem suffixes. So here we just use
+# bytes to make sure everything works correctly.
+zram_sizes="2097152" # 2MB
+zram_mem_limits="2M"
+zram_filesystems="ext4"
+zram_algs="lzo"
+
+zram_fill_fs()
+{
+	for i in $(seq $dev_start $dev_end); do
+		echo "fill zram$i..."
+		local b=0
+		while [ true ]; do
+			dd conv=notrunc if=/dev/zero of=zram${i}/file \
+				oflag=append count=1 bs=1024 status=none \
+				> /dev/null 2>&1 || break
+			b=$(($b + 1))
+		done
+		echo "zram$i can be filled with '$b' KB"
+
+		local mem_used_total=`awk '{print $3}' "/sys/block/zram$i/mm_stat"`
+		local v=$((100 * 1024 * $b / $mem_used_total))
+		if [ "$v" -lt 100 ]; then
+			 echo "FAIL compression ratio: 0.$v:1"
+			 ERR_CODE=-1
+			 return
+		fi
+
+		echo "zram compression ratio: $(echo "scale=2; $v / 100 " | bc):1: OK"
+	done
+}
+
+check_prereqs
+zram_load
+zram_max_streams
+zram_compress_alg
+zram_set_disksizes
+zram_set_memlimit
+zram_makefs
+zram_mount
+
+zram_fill_fs
+zram_cleanup
+
+if [ $ERR_CODE -ne 0 ]; then
+	echo "$TCID : [FAIL]"
+else
+	echo "$TCID : [PASS]"
+fi
diff --git a/tools/testing/selftests/zram/zram02.sh b/tools/testing/selftests/zram/zram02.sh
new file mode 100755
index 000000000..2418b0c4e
--- /dev/null
+++ b/tools/testing/selftests/zram/zram02.sh
@@ -0,0 +1,44 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2015 Oracle and/or its affiliates. All Rights Reserved.
+#
+# Test checks that we can create swap zram device.
+#
+# Author: Alexey Kodanev <alexey.kodanev@oracle.com>
+# Modified: Naresh Kamboju <naresh.kamboju@linaro.org>
+
+TCID="zram02"
+ERR_CODE=0
+
+. ./zram_lib.sh
+
+# Test will create the following number of zram devices:
+dev_num=1
+# This is a list of parameters for zram devices.
+# Number of items must be equal to 'dev_num' parameter.
+zram_max_streams="2"
+
+# The zram sysfs node 'disksize' value can be either in bytes,
+# or you can use mem suffixes. But in some old kernels, mem
+# suffixes are not supported, for example, in RHEL6.6GA's kernel
+# layer, it uses strict_strtoull() to parse disksize which does
+# not support mem suffixes, in some newer kernels, they use
+# memparse() which supports mem suffixes. So here we just use
+# bytes to make sure everything works correctly.
+zram_sizes="1048576" # 1M
+zram_mem_limits="1M"
+
+check_prereqs
+zram_load
+zram_max_streams
+zram_set_disksizes
+zram_set_memlimit
+zram_makeswap
+zram_swapoff
+zram_cleanup
+
+if [ $ERR_CODE -ne 0 ]; then
+	echo "$TCID : [FAIL]"
+else
+	echo "$TCID : [PASS]"
+fi
diff --git a/tools/testing/selftests/zram/zram_lib.sh b/tools/testing/selftests/zram/zram_lib.sh
new file mode 100755
index 000000000..0d44d8388
--- /dev/null
+++ b/tools/testing/selftests/zram/zram_lib.sh
@@ -0,0 +1,269 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0-or-later
+# Copyright (c) 2015 Oracle and/or its affiliates. All Rights Reserved.
+#
+# Author: Alexey Kodanev <alexey.kodanev@oracle.com>
+# Modified: Naresh Kamboju <naresh.kamboju@linaro.org>
+
+dev_makeswap=-1
+dev_mounted=-1
+dev_start=0
+dev_end=-1
+module_load=-1
+sys_control=-1
+# Kselftest framework requirement - SKIP code is 4.
+ksft_skip=4
+kernel_version=`uname -r | cut -d'.' -f1,2`
+kernel_major=${kernel_version%.*}
+kernel_minor=${kernel_version#*.}
+
+trap INT
+
+check_prereqs()
+{
+	local msg="skip all tests:"
+	local uid=$(id -u)
+
+	if [ $uid -ne 0 ]; then
+		echo $msg must be run as root >&2
+		exit $ksft_skip
+	fi
+}
+
+kernel_gte()
+{
+	major=${1%.*}
+	minor=${1#*.}
+
+	if [ $kernel_major -gt $major ]; then
+		return 0
+	elif [ $kernel_major -eq $major ] && [ $kernel_minor -ge $minor ]; then
+		return 0
+	fi
+
+	return 1
+}
+
+zram_cleanup()
+{
+	echo "zram cleanup"
+	local i=
+	for i in $(seq $dev_start $dev_makeswap); do
+		swapoff /dev/zram$i
+	done
+
+	for i in $(seq $dev_start $dev_mounted); do
+		umount /dev/zram$i
+	done
+
+	for i in $(seq $dev_start $dev_end); do
+		echo 1 > /sys/block/zram${i}/reset
+		rm -rf zram$i
+	done
+
+	if [ $sys_control -eq 1 ]; then
+		for i in $(seq $dev_start $dev_end); do
+			echo $i > /sys/class/zram-control/hot_remove
+		done
+	fi
+
+	if [ $module_load -eq 1 ]; then
+		rmmod zram > /dev/null 2>&1
+	fi
+}
+
+zram_load()
+{
+	echo "create '$dev_num' zram device(s)"
+
+	# zram module loaded, new kernel
+	if [ -d "/sys/class/zram-control" ]; then
+		echo "zram modules already loaded, kernel supports" \
+			"zram-control interface"
+		dev_start=$(ls /dev/zram* | wc -w)
+		dev_end=$(($dev_start + $dev_num - 1))
+		sys_control=1
+
+		for i in $(seq $dev_start $dev_end); do
+			cat /sys/class/zram-control/hot_add > /dev/null
+		done
+
+		echo "all zram devices (/dev/zram$dev_start~$dev_end" \
+			"successfully created"
+		return 0
+	fi
+
+	# detect old kernel or built-in
+	modprobe zram num_devices=$dev_num
+	if [ ! -d "/sys/class/zram-control" ]; then
+		if grep -q '^zram' /proc/modules; then
+			rmmod zram > /dev/null 2>&1
+			if [ $? -ne 0 ]; then
+				echo "zram module is being used on old kernel" \
+					"without zram-control interface"
+				exit $ksft_skip
+			fi
+		else
+			echo "test needs CONFIG_ZRAM=m on old kernel without" \
+				"zram-control interface"
+			exit $ksft_skip
+		fi
+		modprobe zram num_devices=$dev_num
+	fi
+
+	module_load=1
+	dev_end=$(($dev_num - 1))
+	echo "all zram devices (/dev/zram0~$dev_end) successfully created"
+}
+
+zram_max_streams()
+{
+	echo "set max_comp_streams to zram device(s)"
+
+	kernel_gte 4.7
+	if [ $? -eq 0 ]; then
+		echo "The device attribute max_comp_streams was"\
+		               "deprecated in 4.7"
+		return 0
+	fi
+
+	local i=$dev_start
+	for max_s in $zram_max_streams; do
+		local sys_path="/sys/block/zram${i}/max_comp_streams"
+		echo $max_s > $sys_path || \
+			echo "FAIL failed to set '$max_s' to $sys_path"
+		sleep 1
+		local max_streams=$(cat $sys_path)
+
+		[ "$max_s" -ne "$max_streams" ] && \
+			echo "FAIL can't set max_streams '$max_s', get $max_stream"
+
+		i=$(($i + 1))
+		echo "$sys_path = '$max_streams'"
+	done
+
+	echo "zram max streams: OK"
+}
+
+zram_compress_alg()
+{
+	echo "test that we can set compression algorithm"
+
+	local i=$dev_start
+	local algs=$(cat /sys/block/zram${i}/comp_algorithm)
+	echo "supported algs: $algs"
+
+	for alg in $zram_algs; do
+		local sys_path="/sys/block/zram${i}/comp_algorithm"
+		echo "$alg" >	$sys_path || \
+			echo "FAIL can't set '$alg' to $sys_path"
+		i=$(($i + 1))
+		echo "$sys_path = '$alg'"
+	done
+
+	echo "zram set compression algorithm: OK"
+}
+
+zram_set_disksizes()
+{
+	echo "set disk size to zram device(s)"
+	local i=$dev_start
+	for ds in $zram_sizes; do
+		local sys_path="/sys/block/zram${i}/disksize"
+		echo "$ds" >	$sys_path || \
+			echo "FAIL can't set '$ds' to $sys_path"
+
+		i=$(($i + 1))
+		echo "$sys_path = '$ds'"
+	done
+
+	echo "zram set disksizes: OK"
+}
+
+zram_set_memlimit()
+{
+	echo "set memory limit to zram device(s)"
+
+	local i=$dev_start
+	for ds in $zram_mem_limits; do
+		local sys_path="/sys/block/zram${i}/mem_limit"
+		echo "$ds" >	$sys_path || \
+			echo "FAIL can't set '$ds' to $sys_path"
+
+		i=$(($i + 1))
+		echo "$sys_path = '$ds'"
+	done
+
+	echo "zram set memory limit: OK"
+}
+
+zram_makeswap()
+{
+	echo "make swap with zram device(s)"
+	local i=$dev_start
+	for i in $(seq $dev_start $dev_end); do
+		mkswap /dev/zram$i > err.log 2>&1
+		if [ $? -ne 0 ]; then
+			cat err.log
+			echo "FAIL mkswap /dev/zram$1 failed"
+		fi
+
+		swapon /dev/zram$i > err.log 2>&1
+		if [ $? -ne 0 ]; then
+			cat err.log
+			echo "FAIL swapon /dev/zram$1 failed"
+		fi
+
+		echo "done with /dev/zram$i"
+		dev_makeswap=$i
+	done
+
+	echo "zram making zram mkswap and swapon: OK"
+}
+
+zram_swapoff()
+{
+	local i=
+	for i in $(seq $dev_start $dev_end); do
+		swapoff /dev/zram$i > err.log 2>&1
+		if [ $? -ne 0 ]; then
+			cat err.log
+			echo "FAIL swapoff /dev/zram$i failed"
+		fi
+	done
+	dev_makeswap=-1
+
+	echo "zram swapoff: OK"
+}
+
+zram_makefs()
+{
+	local i=$dev_start
+	for fs in $zram_filesystems; do
+		# if requested fs not supported default it to ext2
+		which mkfs.$fs > /dev/null 2>&1 || fs=ext2
+
+		echo "make $fs filesystem on /dev/zram$i"
+		mkfs.$fs /dev/zram$i > err.log 2>&1
+		if [ $? -ne 0 ]; then
+			cat err.log
+			echo "FAIL failed to make $fs on /dev/zram$i"
+		fi
+		i=$(($i + 1))
+		echo "zram mkfs.$fs: OK"
+	done
+}
+
+zram_mount()
+{
+	local i=0
+	for i in $(seq $dev_start $dev_end); do
+		echo "mount /dev/zram$i"
+		mkdir zram$i
+		mount /dev/zram$i zram$i > /dev/null || \
+			echo "FAIL mount /dev/zram$i failed"
+		dev_mounted=$i
+	done
+
+	echo "zram mount of zram device(s): OK"
+}