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

1 files changed, 177 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-bus-dax b/Documentation/ABI/testing/sysfs-bus-dax
new file mode 100644
index 000000000..60703fffa
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-dax
@@ -0,0 +1,177 @@
+What:		/sys/bus/dax/devices/daxX.Y/align
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RW) Provides a way to specify an alignment for a dax device.
+		Values allowed are constrained by the physical address ranges
+		that back the dax device, and also by arch requirements.
+
+What:		/sys/bus/dax/devices/daxX.Y/mapping
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(WO) Provides a way to allocate a mapping range under a dax
+		device. Specified in the format <start>-<end>.
+
+What:		/sys/bus/dax/devices/daxX.Y/mapping[0..N]/start
+What:		/sys/bus/dax/devices/daxX.Y/mapping[0..N]/end
+What:		/sys/bus/dax/devices/daxX.Y/mapping[0..N]/page_offset
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) A dax device may have multiple constituent discontiguous
+		address ranges. These are represented by the different
+		'mappingX' subdirectories. The 'start' attribute indicates the
+		start physical address for the given range. The 'end' attribute
+		indicates the end physical address for the given range. The
+		'page_offset' attribute indicates the offset of the current
+		range in the dax device.
+
+What:		/sys/bus/dax/devices/daxX.Y/resource
+Date:		June, 2019
+KernelVersion:	v5.3
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) The resource attribute indicates the starting physical
+		address of a dax device. In case of a device with multiple
+		constituent ranges, it indicates the starting address of the
+		first range.
+
+What:		/sys/bus/dax/devices/daxX.Y/size
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RW) The size attribute indicates the total size of a dax
+		device. For creating subdivided dax devices, or for resizing
+		an existing device, the new size can be written to this as
+		part of the reconfiguration process.
+
+What:		/sys/bus/dax/devices/daxX.Y/numa_node
+Date:		November, 2019
+KernelVersion:	v5.5
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) If NUMA is enabled and the platform has affinitized the
+		backing device for this dax device, emit the CPU node
+		affinity for this device.
+
+What:		/sys/bus/dax/devices/daxX.Y/target_node
+Date:		February, 2019
+KernelVersion:	v5.1
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) The target-node attribute is the Linux numa-node that a
+		device-dax instance may create when it is online. Prior to
+		being online the device's 'numa_node' property reflects the
+		closest online cpu node which is the typical expectation of a
+		device 'numa_node'. Once it is online it becomes its own
+		distinct numa node.
+
+What:		$(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/available_size
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) The available_size attribute tracks available dax region
+		capacity. This only applies to volatile hmem devices, not pmem
+		devices, since pmem devices are defined by nvdimm namespace
+		boundaries.
+
+What:		$(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/size
+Date:		July, 2017
+KernelVersion:	v5.1
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) The size attribute indicates the size of a given dax region
+		in bytes.
+
+What:		$(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/align
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) The align attribute indicates alignment of the dax region.
+		Changes on align may not always be valid, when say certain
+		mappings were created with 2M and then we switch to 1G. This
+		validates all ranges against the new value being attempted, post
+		resizing.
+
+What:		$(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/seed
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) The seed device is a concept for dynamic dax regions to be
+		able to split the region amongst multiple sub-instances.  The
+		seed device, similar to libnvdimm seed devices, is a device
+		that starts with zero capacity allocated and unbound to a
+		driver.
+
+What:		$(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/create
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RW) The create interface to the dax region provides a way to
+		create a new unconfigured dax device under the given region, which
+		can then be configured (with a size etc.) and then probed.
+
+What:		$(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/delete
+Date:		October, 2020
+KernelVersion:	v5.10
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(WO) The delete interface for a dax region provides for deletion
+		of any 0-sized and idle dax devices.
+
+What:		$(readlink -f /sys/bus/dax/devices/daxX.Y)/../dax_region/id
+Date:		July, 2017
+KernelVersion:	v5.1
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RO) The id attribute indicates the region id of a dax region.
+
+What:		/sys/bus/dax/devices/daxX.Y/memmap_on_memory
+Date:		January, 2024
+KernelVersion:	v6.8
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RW) Control the memmap_on_memory setting if the dax device
+		were to be hotplugged as system memory. This determines whether
+		the 'altmap' for the hotplugged memory will be placed on the
+		device being hotplugged (memmap_on_memory=1) or if it will be
+		placed on regular memory (memmap_on_memory=0). This attribute
+		must be set before the device is handed over to the 'kmem'
+		driver (i.e.  hotplugged into system-ram). Additionally, this
+		depends on CONFIG_MHP_MEMMAP_ON_MEMORY, and a globally enabled
+		memmap_on_memory parameter for memory_hotplug. This is
+		typically set on the kernel command line -
+		memory_hotplug.memmap_on_memory set to 'true' or 'force'."
+
+What:		/sys/bus/dax/devices/daxX.Y/state
+Contact:	nvdimm@lists.linux.dev
+Description:
+		(RW) Controls the state of the memory region.
+		Applies to all memory blocks associated with the device.
+		Only applies to dax_kmem devices.
+
+		Reading returns the current state; the writable states mirror
+		the per-block /sys/devices/system/memory/memoryX/state ABI::
+
+		  "unplugged": memory blocks are not present
+		  "online": memory is online, zone chosen by the kernel
+		  "online_kernel": memory is online in ZONE_NORMAL
+		  "online_movable": memory is online in ZONE_MOVABLE
+
+		"offline" (memory blocks are present but offline) may also be
+		reported - this happens when the device is bound while the
+		auto_online_blocks policy is "offline".  It cannot be written,
+		as it's not useful and creates device destruction races.
+
+		A device can only be onlined from the "unplugged" state, so a
+		device must be returned to "unplugged" before it can be onlined
+		into a different state.