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Clean up zswap output leaks and missing-file reads #20

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Merged
modem7 merged 1 commit into from
Jul 31, 2026
Merged

Clean up zswap output leaks and missing-file reads #20

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24 changes: 16 additions & 8 deletions Bash/Server scripts/zram-to-zswap.sh
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Original file line number Diff line number Diff line change
Expand Up @@ -332,11 +332,15 @@ if [[ -e /sys/module/zswap/parameters/enabled ]]; then
# the kernel request_module() it on demand, which kernel lockdown (common
# with Secure Boot enabled) blocks via sysfs even for root.
modprobe zsmalloc 2>/dev/null || true
# Each write is grouped in braces so the 2>/dev/null takes effect before
# the redirection into the sysfs file is attempted — bash prints its own
# "Permission denied" diagnostic for a failed target-file open *before*
# a same-line 2>/dev/null on the command would otherwise suppress it.
RUNTIME_OK=true
echo "${ZSWAP_COMPRESSOR}" > /sys/module/zswap/parameters/compressor 2>/dev/null || RUNTIME_OK=false
echo zsmalloc > /sys/module/zswap/parameters/zpool 2>/dev/null || RUNTIME_OK=false
echo "${ZSWAP_POOL_PERCENT}" > /sys/module/zswap/parameters/max_pool_percent 2>/dev/null || RUNTIME_OK=false
echo 1 > /sys/module/zswap/parameters/enabled 2>/dev/null || RUNTIME_OK=false
{ echo "${ZSWAP_COMPRESSOR}" > /sys/module/zswap/parameters/compressor; } 2>/dev/null || RUNTIME_OK=false
{ echo zsmalloc > /sys/module/zswap/parameters/zpool; } 2>/dev/null || RUNTIME_OK=false
{ echo "${ZSWAP_POOL_PERCENT}" > /sys/module/zswap/parameters/max_pool_percent; } 2>/dev/null || RUNTIME_OK=false
{ echo 1 > /sys/module/zswap/parameters/enabled; } 2>/dev/null || RUNTIME_OK=false
if ! $RUNTIME_OK; then
echo " WARNING: one or more zswap sysfs writes were denied (kernel lockdown /"
echo " Secure Boot commonly blocks dynamic module loading via sysfs, even as root)."
Expand Down Expand Up @@ -390,10 +394,14 @@ hr "Result"
swapon --show
free -h
if [[ -e /sys/module/zswap/parameters/enabled ]]; then
ZSWAP_ENABLED_NOW=$(cat /sys/module/zswap/parameters/enabled)
ZSWAP_COMPRESSOR_NOW=$(cat /sys/module/zswap/parameters/compressor)
ZSWAP_ZPOOL_NOW=$(cat /sys/module/zswap/parameters/zpool)
ZSWAP_POOL_PERCENT_NOW=$(cat /sys/module/zswap/parameters/max_pool_percent)
# Individual parameter files can go missing even when .../enabled exists —
# seen in the wild where a denied zpool write left that one file gone by
# the time we get here. Check each before reading rather than assuming.
read_zswap_param() { [[ -e "/sys/module/zswap/parameters/$1" ]] && cat "/sys/module/zswap/parameters/$1" || echo "(not present)"; }
ZSWAP_ENABLED_NOW=$(read_zswap_param enabled)
ZSWAP_COMPRESSOR_NOW=$(read_zswap_param compressor)
ZSWAP_ZPOOL_NOW=$(read_zswap_param zpool)
ZSWAP_POOL_PERCENT_NOW=$(read_zswap_param max_pool_percent)
echo "zswap enabled: ${ZSWAP_ENABLED_NOW}"
echo "zswap compressor: ${ZSWAP_COMPRESSOR_NOW}"
echo "zswap zpool: ${ZSWAP_ZPOOL_NOW}"
Expand Down