Add a kselftest for the dax/kmem whole-device "state" sysfs attribute (/sys/bus/dax/devices/daxX.Y/state), which transitions a kmem-backed dax device between "unplugged", "online" and "online_movable". The kselftest also includes a test to demonstrate the force-unbind does not deadlock - but this is a destructive test. The dax device can never be rebound after doing this. Provisioning a devdax device and binding it to kmem needs daxctl/ndctl out of scope for an in-tree selftest, so the test discovers an already kmem-bound dax device and SKIPs when none are present or the memory cannot be freed to reach a known baseline. When a device is available it validates the interface contract: - online / online_movable actually add memory (MemTotal grows), - online is idempotent, - switching between online types without unplug is rejected, - unplug removes memory and the reported state is "unplugged" - invalid input is rejected. One specific regression test: online -> unplug -> online_movable -> unplug Re-online must re-reserve per-range resources so subsequent unplug actually offlines and removes instead of silently reporting success while the memory stays online. Signed-off-by: Gregory Price --- tools/testing/selftests/Makefile | 1 + tools/testing/selftests/dax/Makefile | 6 + tools/testing/selftests/dax/config | 4 + .../testing/selftests/dax/dax-kmem-hotplug.sh | 190 ++++++++++++++++++ tools/testing/selftests/dax/settings | 1 + 5 files changed, 202 insertions(+) create mode 100644 tools/testing/selftests/dax/Makefile create mode 100644 tools/testing/selftests/dax/config create mode 100755 tools/testing/selftests/dax/dax-kmem-hotplug.sh create mode 100644 tools/testing/selftests/dax/settings diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile index 6e59b8f63e41..8c2b4f97619c 100644 --- a/tools/testing/selftests/Makefile +++ b/tools/testing/selftests/Makefile @@ -14,6 +14,7 @@ TARGETS += core TARGETS += cpufreq TARGETS += cpu-hotplug TARGETS += damon +TARGETS += dax TARGETS += devices/error_logs TARGETS += devices/probe TARGETS += dmabuf-heaps diff --git a/tools/testing/selftests/dax/Makefile b/tools/testing/selftests/dax/Makefile new file mode 100644 index 000000000000..25a4f3d73a5b --- /dev/null +++ b/tools/testing/selftests/dax/Makefile @@ -0,0 +1,6 @@ +# SPDX-License-Identifier: GPL-2.0 +all: + +TEST_PROGS := dax-kmem-hotplug.sh + +include ../lib.mk diff --git a/tools/testing/selftests/dax/config b/tools/testing/selftests/dax/config new file mode 100644 index 000000000000..4c9aaeb6ceb4 --- /dev/null +++ b/tools/testing/selftests/dax/config @@ -0,0 +1,4 @@ +CONFIG_DEV_DAX=m +CONFIG_DEV_DAX_KMEM=m +CONFIG_MEMORY_HOTPLUG=y +CONFIG_MEMORY_HOTREMOVE=y diff --git a/tools/testing/selftests/dax/dax-kmem-hotplug.sh b/tools/testing/selftests/dax/dax-kmem-hotplug.sh new file mode 100755 index 000000000000..c8bbaf6178ed --- /dev/null +++ b/tools/testing/selftests/dax/dax-kmem-hotplug.sh @@ -0,0 +1,190 @@ +#!/bin/bash +# SPDX-License-Identifier: GPL-2.0 +# +# Exercise the dax/kmem "state" sysfs attribute: +# /sys/bus/dax/devices/daxX.Y/state -> unplugged | online | online_kernel | online_movable +# +# The test needs a dax device already bound to the kmem driver. +# If no suitable device is found the tests SKIP. +# +# A dax device can be provisioned with the memmap= boot param, e.g.: +# memmap=2G!4G +# +# then, in the booted system: +# +# ndctl create-namespace -m devdax -e namespace0.0 -f +# daxctl reconfigure-device -N -m system-ram dax0.0 # bind kmem +# ./dax-kmem-hotplug.sh + +# shellcheck disable=SC1091 +DIR="$(dirname "$(readlink -f "$0")")" +. "$DIR"/../kselftest/ktap_helpers.sh + +DAX_BASE=/sys/bus/dax/devices + +memtotal_kb() { awk '/^MemTotal:/ {print $2}' /proc/meminfo; } +get_state() { cat "$HP" 2>/dev/null; } +# set_state STATE -- write a state to the state attribute; returns the +# write's exit status (0 = accepted by the kernel) +set_state() { echo "$1" > "$HP" 2>/dev/null; } + +find_kmem_dax() { + local d drv + for d in "$DAX_BASE"/dax*; do + [ -e "$d/state" ] || continue + drv=$(readlink "$d/driver" 2>/dev/null) + [ "$(basename "${drv:-}")" = kmem ] || continue + basename "$d" + return 0 + done + return 1 +} + +ktap_print_header + +if [ "$UID" != 0 ]; then + ktap_skip_all "must be run as root" + exit "$KSFT_SKIP" +fi + +DAX=$(find_kmem_dax) +if [ -z "$DAX" ]; then + ktap_skip_all "no kmem-bound dax device with a state attribute" + exit "$KSFT_SKIP" +fi +HP=$DAX_BASE/$DAX/state +ORIG=$(get_state) + +# A failure to reach the baseline is environmental (memory in use), not an +# interface failure, so skip rather than fail. +set_state unplugged; rc=$? +if [ "$rc" != 0 ] || [ "$(get_state)" != unplugged ]; then + ktap_skip_all "$DAX: cannot reach 'unplugged' baseline (memory in use?)" + [ -n "$ORIG" ] && set_state "$ORIG" + exit "$KSFT_SKIP" +fi +mt_unplugged=$(memtotal_kb) + +DRV=/sys/bus/dax/drivers/kmem +AOB=/sys/devices/system/memory/auto_online_blocks + +ktap_print_msg "using $DAX (initial state was: $ORIG)" +ktap_set_plan 8 + +# A public (N_MEMORY) kmem node onlined into a kernel zone (online/online_kernel) +# collects unmovable allocations and can then never be offlined, which would +# wedge the device for the rest of this test. So this test only ever +# successfully onlines online_movable, the one mode that is reliably unpluggable. + +set_state online_movable; rc=$? +mt_online=$(memtotal_kb) +if [ "$rc" = 0 ] && [ "$(get_state)" = online_movable ] && [ "$mt_online" -gt "$mt_unplugged" ]; then + ktap_test_pass "online_movable: state=online_movable, MemTotal $mt_unplugged -> $mt_online kB" +else + ktap_test_fail "online_movable: rc=$rc state=$(get_state) MemTotal $mt_unplugged -> $mt_online" +fi + +set_state online_movable; rc=$? +if [ "$rc" = 0 ] && [ "$(get_state)" = online_movable ]; then + ktap_test_pass "online_movable idempotent" +else + ktap_test_fail "online_movable idempotent: rc=$rc state=$(get_state)" +fi + +# A different online type is rejected without an intervening unplug. The write +# is refused before any hotplug, so this never actually onlines a kernel zone. +set_state online_kernel; rc=$? +if [ "$rc" != 0 ] && [ "$(get_state)" = online_movable ]; then + ktap_test_pass "reject online_kernel without intervening unplug (no kernel-zone online)" +else + ktap_test_fail "online_movable->online_kernel not rejected: rc=$rc state=$(get_state)" +fi + +set_state unplugged; rc=$? +mt=$(memtotal_kb) +if [ "$rc" = 0 ] && [ "$(get_state)" = unplugged ] && [ "$mt" -lt "$mt_online" ]; then + ktap_test_pass "unplug from online_movable: MemTotal $mt_online -> $mt kB" +else + ktap_test_fail "unplug from online_movable: rc=$rc state=$(get_state) MemTotal $mt_online -> $mt" +fi + +before=$(get_state) +set_state bogus_state; rc=$? +if [ "$rc" != 0 ] && [ "$(get_state)" = "$before" ]; then + ktap_test_pass "reject invalid state string" +else + ktap_test_fail "invalid state not rejected: rc=$rc state=$(get_state)" +fi + +# The online_movable -> unplug cycle once regressed: a re-online failed to +# re-reserve the per-range resources, so a later unplug reported success while +# leaving the memory online. Assert each iteration really adds and frees memory. +set_state unplugged +cycle_ok=1; fail_i=0; on=0; off=0 +for i in 1 2 3; do + if ! set_state online_movable; then cycle_ok=0; fail_i=$i; break; fi + on=$(memtotal_kb) + if ! set_state unplugged; then cycle_ok=0; fail_i=$i; break; fi + off=$(memtotal_kb) + if [ "$on" -le "$mt_unplugged" ] || [ "$off" -ge "$on" ]; then + cycle_ok=0; fail_i=$i; break + fi +done +if [ "$cycle_ok" = 1 ]; then + ktap_test_pass "online_movable/unplug cycle re-acquires resources (3x: added and freed each time)" +else + ktap_test_fail "online_movable/unplug cycle regressed at iteration $fail_i (on=$on off=$off baseline=$mt_unplugged)" +fi + +# change system default online policy while the device is unbound, and show +# the new system default policy is utilized across bindings. +set_state unplugged +if [ -w "$AOB" ] && [ -w "$DRV/unbind" ] && [ -w "$DRV/bind" ]; then + orig_aob=$(cat "$AOB") + echo "$DAX" > "$DRV/unbind" 2>/dev/null + echo offline > "$AOB" 2>/dev/null + echo "$DAX" > "$DRV/bind" 2>/dev/null + sleep 1 + st=$(get_state) + echo "$orig_aob" > "$AOB" 2>/dev/null # restore system policy + if [ "$st" = offline ]; then + ktap_test_pass "online policy resolved at bind: auto_online_blocks=offline -> state=offline" + else + ktap_test_fail "bind-time policy not honored: state=$st (expected offline)" + fi + set_state unplugged 2>/dev/null +else + ktap_test_skip "auto_online_blocks or driver bind/unbind not writable" +fi + +[ -n "$ORIG" ] && set_state "$ORIG" + +# DESTRUCTIVE: unbinding the driver while memory is online causes the resources +# to leak - but the unbind should not deadlock. Instead the driver leaks it +# with a single "stuck online" warning. This leaves the memory online and the +# device unbound until reboot, so it runs last - and only if we can run it, +# leaving the restored state above untouched otherwise. online_movable only: +# this test never onlines a public node into a kernel zone. +if [ -w "$DRV/unbind" ]; then + set_state unplugged; set_state online_movable +fi +if [ "$(get_state)" = online_movable ] && [ -w "$DRV/unbind" ]; then + mt_on=$(memtotal_kb) + dmesg -C 2>/dev/null + echo "$DAX" > "$DRV/unbind" 2>/dev/null + mt_after=$(memtotal_kb) + # The leaked "System RAM (kmem)" regions stay in the iomem tree; reading + # their names dereferences res_name, which a buggy unbind already freed. + # Walk /proc/iomem to provoke that use-after-free (caught by KASAN). + cat /proc/iomem > /dev/null 2>&1 + splat=$(dmesg 2>/dev/null | grep -ciE "KASAN|BUG:|use-after-free|general protection|Oops|refcount_t") + if [ "$splat" = 0 ] && [ "$mt_after" -ge "$mt_on" ]; then + ktap_test_pass "unbind while online: memory left online, no UAF/oops (MemTotal $mt_on -> $mt_after kB)" + else + ktap_test_fail "unbind while online regressed: splat=$splat MemTotal $mt_on -> $mt_after kB" + fi +else + ktap_test_skip "could not online device for unbind-while-online test" +fi + +ktap_finished diff --git a/tools/testing/selftests/dax/settings b/tools/testing/selftests/dax/settings new file mode 100644 index 000000000000..ba4d85f74cd6 --- /dev/null +++ b/tools/testing/selftests/dax/settings @@ -0,0 +1 @@ +timeout=90 -- 2.53.0-Meta