#!/bin/bash
# Copyright (c) 2015 Oracle and/or its affiliates. All Rights Reserved.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of
# the License, or (at your option) any later version.
#
# This program is distributed in the hope that it would be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.	See the
# GNU General Public License for more details.
#
# 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()
{
	local mem_free0=$(free -m | awk 'NR==2 {print $4}')

	for i in $(seq 0 $(($dev_num - 1))); 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"
	done

	local mem_free1=$(free -m | awk 'NR==2 {print $4}')
	local used_mem=$(($mem_free0 - $mem_free1))

	local total_size=0
	for sm in $zram_sizes; do
		local s=$(echo $sm | sed 's/M//')
		total_size=$(($total_size + $s))
	done

	echo "zram used ${used_mem}M, zram disk sizes ${total_size}M"

	local v=$((100 * $total_size / $used_mem))

	if [ "$v" -lt 100 ]; then
		echo "FAIL compression ratio: 0.$v:1"
		ERR_CODE=-1
		zram_cleanup
		return
	fi

	echo "zram compression ratio: $(echo "scale=2; $v / 100 " | bc):1: OK"
}

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
zram_unload

if [ $ERR_CODE -ne 0 ]; then
	echo "$TCID : [FAIL]"
else
	echo "$TCID : [PASS]"
fi
4dc3341'>root</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net?id=966d2b04e070bc040319aaebfec09e0144dc3341'>net</a>/<a href='/cgit.cgi/linux/net-next.git/commit/net/batman-adv?id=966d2b04e070bc040319aaebfec09e0144dc3341'>batman-adv</a></div><div class='content'><div class='cgit-panel'><b>diff options</b><form method='get'><input type='hidden' name='id' value='966d2b04e070bc040319aaebfec09e0144dc3341'/><table><tr><td colspan='2'/></tr><tr><td class='label'>context:</td><td class='ctrl'><select name='context' onchange='this.form.submit();'><option value='1'>1</option><option value='2'>2</option><option value='3' selected='selected'>3</option><option value='4'>4</option><option value='5'>5</option><option value='6'>6</option><option value='7'>7</option><option value='8'>8</option><option value='9'>9</option><option value='10'>10</option><option value='15'>15</option><option value='20'>20</option><option value='25'>25</option><option value='30'>30</option><option value='35'>35</option><option value='40'>40</option></select></td></tr><tr><td class='label'>space:</td><td class='ctrl'><select name='ignorews' onchange='this.form.submit();'><option value='0' selected='selected'>include</option><option value='1'>ignore</option></select></td></tr><tr><td class='label'>mode:</td><td class='ctrl'><select name='dt' onchange='this.form.submit();'><option value='0' selected='selected'>unified</option><option value='1'>ssdiff</option><option value='2'>stat only</option></select></td></tr><tr><td/><td class='ctrl'><noscript><input type='submit' value='reload'/></noscript></td></tr></table></form></div><table summary='commit info' class='commit-info'>
<tr><th>author</th><td>Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;</td><td class='right'>2017-01-28 06:42:20 -0600</td></tr>
<tr><th>committer</th><td>Tejun Heo &lt;tj@kernel.org&gt;</td><td class='right'>2017-01-28 07:49:42 -0500</td></tr>
<tr><th>commit</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/batman-adv?id=966d2b04e070bc040319aaebfec09e0144dc3341'>966d2b04e070bc040319aaebfec09e0144dc3341</a> (<a href='/cgit.cgi/linux/net-next.git/patch/net/batman-adv?id=966d2b04e070bc040319aaebfec09e0144dc3341'>patch</a>)</td></tr>
<tr><th>tree</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/tree/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>4b96156e3d1dd4dfd6039b7c219c9dc4616da52d</a> /<a href='/cgit.cgi/linux/net-next.git/tree/net/batman-adv?id=966d2b04e070bc040319aaebfec09e0144dc3341'>net/batman-adv</a></td></tr>
<tr><th>parent</th><td colspan='2' class='oid'><a href='/cgit.cgi/linux/net-next.git/commit/net/batman-adv?id=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>1b1bc42c1692e9b62756323c675a44cb1a1f9dbd</a> (<a href='/cgit.cgi/linux/net-next.git/diff/net/batman-adv?id=966d2b04e070bc040319aaebfec09e0144dc3341&amp;id2=1b1bc42c1692e9b62756323c675a44cb1a1f9dbd'>diff</a>)</td></tr></table>
<div class='commit-subject'>percpu-refcount: fix reference leak during percpu-atomic transition</div><div class='commit-msg'>percpu_ref_tryget() and percpu_ref_tryget_live() should return
"true" IFF they acquire a reference. But the return value from
atomic_long_inc_not_zero() is a long and may have high bits set,
e.g. PERCPU_COUNT_BIAS, and the return value of the tryget routines
is bool so the reference may actually be acquired but the routines
return "false" which results in a reference leak since the caller
assumes it does not need to do a corresponding percpu_ref_put().

This was seen when performing CPU hotplug during I/O, as hangs in
blk_mq_freeze_queue_wait where percpu_ref_kill (blk_mq_freeze_queue_start)
raced with percpu_ref_tryget (blk_mq_timeout_work).
Sample stack trace:

__switch_to+0x2c0/0x450
__schedule+0x2f8/0x970
schedule+0x48/0xc0
blk_mq_freeze_queue_wait+0x94/0x120
blk_mq_queue_reinit_work+0xb8/0x180
blk_mq_queue_reinit_prepare+0x84/0xa0
cpuhp_invoke_callback+0x17c/0x600
cpuhp_up_callbacks+0x58/0x150
_cpu_up+0xf0/0x1c0
do_cpu_up+0x120/0x150
cpu_subsys_online+0x64/0xe0
device_online+0xb4/0x120
online_store+0xb4/0xc0
dev_attr_store+0x68/0xa0
sysfs_kf_write+0x80/0xb0
kernfs_fop_write+0x17c/0x250
__vfs_write+0x6c/0x1e0
vfs_write+0xd0/0x270
SyS_write+0x6c/0x110
system_call+0x38/0xe0

Examination of the queue showed a single reference (no PERCPU_COUNT_BIAS,
and __PERCPU_REF_DEAD, __PERCPU_REF_ATOMIC set) and no requests.
However, conditions at the time of the race are count of PERCPU_COUNT_BIAS + 0
and __PERCPU_REF_DEAD and __PERCPU_REF_ATOMIC set.

The fix is to make the tryget routines use an actual boolean internally instead
of the atomic long result truncated to a int.

Fixes: e625305b3907 percpu-refcount: make percpu_ref based on longs instead of ints
Link: https://bugzilla.kernel.org/show_bug.cgi?id=190751
Signed-off-by: Douglas Miller &lt;dougmill@linux.vnet.ibm.com&gt;
Reviewed-by: Jens Axboe &lt;axboe@fb.com&gt;
Signed-off-by: Tejun Heo &lt;tj@kernel.org&gt;
Fixes: e625305b3907 ("percpu-refcount: make percpu_ref based on longs instead of ints")
Cc: stable@vger.kernel.org # v3.18+
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=966d2b04e070bc040319aaebfec09e0144dc3341'>Diffstat</a> (limited to 'net/batman-adv')</div><table summary='diffstat' class='diffstat'>