Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

4 files changed, 328 insertions, 0 deletions

diff --git a/tools/testing/selftests/dax/Makefile b/tools/testing/selftests/dax/Makefile
new file mode 100644
index 000000000..25a4f3d73
--- /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 000000000..4c9aaeb6c
--- /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 000000000..9299120ee
--- /dev/null
+++ b/tools/testing/selftests/dax/dax-kmem-hotplug.sh
@@ -0,0 +1,317 @@
+#!/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.
+#
+# This test mutates a device's memory: online/offline cycles migrate any
+# in-use pages, and the optional unbind subtest wedges the device until
+# reboot. The tester must identify the target device and opt into the
+# destructive unbind tests.
+#
+#   DAX_KMEM_TEST_DEV=daxX.Y   test this specific device
+#   DAX_KMEM_TEST_DEV=auto     auto-discover the first kmem-bound dax device
+#                              (best-effort: it may be a device in use!)
+#   DAX_KMEM_TEST_UNBIND=1     also run the destructive unbind-while-online test
+#
+# If DAX_KMEM_TEST_DEV is unset the whole test SKIPs.
+#
+# 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_TEST_DEV=auto ./dax-kmem-hotplug.sh
+
+# shellcheck disable=SC1091
+DIR="$(dirname "$(readlink -f "$0")")"
+. "$DIR"/../kselftest/ktap_helpers.sh
+
+DAX_BASE=/sys/bus/dax/devices
+MEM_BASE=/sys/devices/system/memory
+
+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; }
+
+is_kmem_dax() {
+	local drv
+	[ -e "$DAX_BASE/$1/state" ] || return 1
+	drv=$(readlink "$DAX_BASE/$1/driver" 2>/dev/null)
+	[ "$(basename "${drv:-}")" = kmem ]
+}
+
+find_kmem_dax() {
+	local d
+	for d in "$DAX_BASE"/dax*; do
+		is_kmem_dax "$(basename "$d")" || continue
+		basename "$d"
+		return 0
+	done
+	return 1
+}
+
+# find_device_blocks -- print every memoryN block backing this dax device.
+# The blocks are derived from the device's own range(s) in /proc/iomem (the
+# reserved resource is named after the device), so we act on *its* blocks
+# rather than guessing by NUMA node - the target node may also hold unrelated
+# (and non-offlineable) memory.
+find_device_blocks() {
+	local bs
+	bs=$(cat "$MEM_BASE/block_size_bytes" 2>/dev/null)	# hex, no leading 0x
+	[ -n "$bs" ] || return 1
+	grep -E " : ${DAX}\$" /proc/iomem | while read -r line; do
+		local range s e i
+		range=${line%% :*}; range=${range// /}
+		s=${range%-*}; e=${range#*-}
+		for (( i = 0x$s / 0x$bs; i <= 0x$e / 0x$bs; i++ )); do
+			echo "memory$i"
+		done
+	done
+}
+
+# find_device_block -- print the first online block backing this dax device.
+find_device_block() {
+	local b
+	for b in $(find_device_blocks); do
+		[ -f "$MEM_BASE/$b/state" ] || continue
+		[ "$(cat "$MEM_BASE/$b/state")" = online ] || continue
+		echo "$b"
+		return 0
+	done
+	return 1
+}
+
+ktap_print_header
+
+if [ "$UID" != 0 ]; then
+	ktap_skip_all "must be run as root"
+	exit "$KSFT_SKIP"
+fi
+
+# Device selection is opt-in - see the header for why.
+DEV_SEL=${DAX_KMEM_TEST_DEV:-}
+if [ -z "$DEV_SEL" ]; then
+	ktap_skip_all "set DAX_KMEM_TEST_DEV=<daxX.Y|auto> to opt in (mutates device memory)"
+	exit "$KSFT_SKIP"
+fi
+if [ "$DEV_SEL" = auto ]; then
+	DAX=$(find_kmem_dax)
+else
+	DAX=$DEV_SEL
+fi
+if [ -z "$DAX" ] || ! is_kmem_dax "$DAX"; then
+	ktap_skip_all "no kmem-bound dax device with a state attribute (${DEV_SEL})"
+	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=$MEM_BASE/auto_online_blocks
+
+ktap_print_msg "using $DAX (initial state was: $ORIG)"
+ktap_set_plan 10
+
+# A public (N_MEMORY) kmem node onlined into a kernel zone (online/online_kernel)
+# collects unmovable allocations and can then never be offlined, which would
+# wedge the device for the rest of this test.  So this test only ever
+# successfully onlines online_movable, the one mode that is reliably unpluggable.
+
+set_state online_movable; rc=$?
+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
+
+# An online_movable -> unplug cycle must re-acquire the per-range resources on
+# each online and release them on each unplug.  Assert every iteration grows
+# MemTotal past the baseline and returns exactly to it; memory left online after
+# unplug (off > baseline) is a partial-free failure.
+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)
+	# online must grow past baseline, and unplug must return to it - a
+	# partial free (memory left online) is a failure, not just off == on.
+	if [ "$on" -le "$mt_unplugged" ] || [ "$off" -gt "$mt_unplugged" ]; 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
+
+# Desync: toggle a block through the legacy per-block memoryN/state interface
+# behind the driver's back, then unplug the whole device via daxX.Y/state.
+#
+# The driver only updates daxX.Y/state on its own writes, so it still reports
+# online_movable while a block underneath is already offline.
+#
+# Whole-device unplug must still succeed (within reason, an actor changing a
+# device from online_movable to online_kernel can no longer guarantee unplug).
+# At the very least, an already-offline block should not produce an error.
+set_state unplugged
+set_state online_movable
+blk=$(find_device_block)
+if [ -n "$blk" ] && echo offline > "$MEM_BASE/$blk/state" 2>/dev/null; then
+	# daxX.Y/state is now stale (still online_movable); unplug the device.
+	set_state unplugged; rc=$?
+	mt=$(memtotal_kb)
+	if [ "$rc" = 0 ] && [ "$(get_state)" = unplugged ] && [ "$mt" -le "$mt_unplugged" ]; then
+		ktap_test_pass "unplug tolerates a block pre-offlined via memoryN/state ($blk)"
+	else
+		ktap_test_fail "desync unplug: rc=$rc state=$(get_state) MemTotal=$mt baseline=$mt_unplugged"
+	fi
+else
+	set_state unplugged 2>/dev/null
+	ktap_test_skip "could not locate a device block to offline for desync test"
+fi
+
+# change system default online policy while the device is unbound, and show
+# the new system default policy is utilized across bindings.
+set_state unplugged
+if [ -w "$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
+
+# Blocks offlined out-of-band (via memoryN/state) leave daxX.Y/state stale
+# (still online_movable) while every block is actually offline.  A driver unbind
+# must still hot-remove the offline memory and free its resources rather than
+# trust the stale state and leak until reboot.  Unbind uses remove_memory(),
+# which never offlines, so removing already-offline blocks is non-destructive and
+# the device rebinds cleanly afterwards.
+if [ -w "$DRV/unbind" ] && [ -w "$DRV/bind" ]; then
+	set_state unplugged
+	set_state online_movable
+	offl_ok=1
+	for b in $(find_device_blocks); do
+		[ -f "$MEM_BASE/$b/state" ] || continue
+		[ "$(cat "$MEM_BASE/$b/state")" = online ] || continue
+		echo offline > "$MEM_BASE/$b/state" 2>/dev/null || offl_ok=0
+	done
+	# daxX.Y/state is now stale (still online_movable) while all blocks are
+	# offline; the unbind must hot-remove them anyway.
+	if [ "$offl_ok" = 1 ] && [ "$(get_state)" = online_movable ]; then
+		echo "$DAX" > "$DRV/unbind" 2>/dev/null
+		mt_after=$(memtotal_kb)
+		leaked=$(grep -cE " : ${DAX}\$" /proc/iomem)	# before rebind
+		echo "$DAX" > "$DRV/bind" 2>/dev/null		# restore for later steps
+		sleep 1
+		if [ "$mt_after" -le "$mt_unplugged" ] && [ "$leaked" = 0 ]; then
+			ktap_test_pass "unbind with stale online state hot-removes offlined blocks (no leak)"
+		else
+			ktap_test_fail "desync unbind leaked: MemTotal=$mt_after baseline=$mt_unplugged iomem_left=$leaked"
+		fi
+		set_state unplugged 2>/dev/null
+	else
+		ktap_test_skip "could not offline all device blocks for desync-unbind test"
+	fi
+else
+	ktap_test_skip "driver bind/unbind not writable for desync-unbind test"
+fi
+
+[ -n "$ORIG" ] && set_state "$ORIG"
+
+# DESTRUCTIVE and opt-in only (DAX_KMEM_TEST_UNBIND=1):
+#
+# unbinding the driver while memory is online causes the resources to leak - but
+# the unbind should not deadlock.  Instead the driver leaks it with a warning.
+
+# This leaves the memory online and the device unbound until reboot, so it runs
+# last and only when explicitly requested.  online_movable only: this test
+# never onlines a public node into a kernel zone.
+
+if [ "${DAX_KMEM_TEST_UNBIND:-}" = 1 ] && [ -w "$DRV/unbind" ]; then
+	set_state unplugged; set_state online_movable
+fi
+if [ "${DAX_KMEM_TEST_UNBIND:-}" = 1 ] && [ "$(get_state)" = online_movable ] &&
+   [ -w "$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 "destructive unbind-while-online test (set DAX_KMEM_TEST_UNBIND=1)"
+fi
+
+ktap_finished
diff --git a/tools/testing/selftests/dax/settings b/tools/testing/selftests/dax/settings
new file mode 100644
index 000000000..ba4d85f74
--- /dev/null
+++ b/tools/testing/selftests/dax/settings
@@ -0,0 +1 @@
+timeout=90