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, 157 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/debugfs-cxl b/Documentation/ABI/testing/debugfs-cxl
new file mode 100644
index 000000000..2989d4da9
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-cxl
@@ -0,0 +1,157 @@
+What:		/sys/kernel/debug/cxl/memX/inject_poison
+Date:		April, 2023
+KernelVersion:	v6.4
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(WO) When a Device Physical Address (DPA) is written to this
+		attribute, the memdev driver sends an inject poison command to
+		the device for the specified address. The DPA must be 64-byte
+		aligned and the length of the injected poison is 64-bytes. If
+		successful, the device returns poison when the address is
+		accessed through the CXL.mem bus. Injecting poison adds the
+		address to the device's Poison List and the error source is set
+		to Injected. In addition, the device adds a poison creation
+		event to its internal Informational Event log, updates the
+		Event Status register, and if configured, interrupts the host.
+		It is not an error to inject poison into an address that
+		already has poison present and no error is returned. If the
+		device returns 'Inject Poison Limit Reached' an -EBUSY error
+		is returned to the user. The inject_poison attribute is only
+		visible for devices supporting the capability.
+
+		TEST-ONLY INTERFACE: This interface is intended for testing
+		and validation purposes only. It is not a data repair mechanism
+		and should never be used on production systems or live data.
+
+		DATA LOSS RISK: For CXL persistent memory (PMEM) devices,
+		poison injection can result in permanent data loss. Injected
+		poison may render data permanently inaccessible even after
+		clearing, as the clear operation writes zeros and does not
+		recover original data.
+
+		SYSTEM STABILITY RISK: For volatile memory, poison injection
+		can cause kernel crashes, system instability, or unpredictable
+		behavior if the poisoned addresses are accessed by running code
+		or critical kernel structures.
+
+What:		/sys/kernel/debug/cxl/memX/clear_poison
+Date:		April, 2023
+KernelVersion:	v6.4
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(WO) When a Device Physical Address (DPA) is written to this
+		attribute, the memdev driver sends a clear poison command to
+		the device for the specified address. Clearing poison removes
+		the address from the device's Poison List and writes 0 (zero)
+		for 64 bytes starting at address. It is not an error to clear
+		poison from an address that does not have poison set. If the
+		device cannot clear poison from the address, -ENXIO is returned.
+		The clear_poison attribute is only visible for devices
+		supporting the capability.
+
+		TEST-ONLY INTERFACE: This interface is intended for testing
+		and validation purposes only. It is not a data repair mechanism
+		and should never be used on production systems or live data.
+
+		CLEAR IS NOT DATA RECOVERY: This operation writes zeros to the
+		specified address range and removes the address from the poison
+		list. It does NOT recover or restore original data that may have
+		been present before poison injection. Any original data at the
+		cleared address is permanently lost and replaced with zeros.
+
+		CLEAR IS NOT A REPAIR MECHANISM: This interface is for testing
+		purposes only and should not be used as a data repair tool.
+		Clearing poison is fundamentally different from data recovery
+		or error correction.
+
+What:		/sys/kernel/debug/cxl/regionX/inject_poison
+Date:		August, 2025
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(WO) When a Host Physical Address (HPA) is written to this
+		attribute, the region driver translates it to a Device
+		Physical Address (DPA) and identifies the corresponding
+		memdev. It then sends an inject poison command to that memdev
+		at the translated DPA. Refer to the memdev ABI entry at:
+		/sys/kernel/debug/cxl/memX/inject_poison for the detailed
+		behavior. This attribute is only visible if all memdevs
+		participating in the region support both inject and clear
+		poison commands.
+
+		TEST-ONLY INTERFACE: This interface is intended for testing
+		and validation purposes only. It is not a data repair mechanism
+		and should never be used on production systems or live data.
+
+		DATA LOSS RISK: For CXL persistent memory (PMEM) devices,
+		poison injection can result in permanent data loss. Injected
+		poison may render data permanently inaccessible even after
+		clearing, as the clear operation writes zeros and does not
+		recover original data.
+
+		SYSTEM STABILITY RISK: For volatile memory, poison injection
+		can cause kernel crashes, system instability, or unpredictable
+		behavior if the poisoned addresses are accessed by running code
+		or critical kernel structures.
+
+What:		/sys/kernel/debug/cxl/regionX/clear_poison
+Date:		August, 2025
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(WO) When a Host Physical Address (HPA) is written to this
+		attribute, the region driver translates it to a Device
+		Physical Address (DPA) and identifies the corresponding
+		memdev. It then sends a clear poison command to that memdev
+		at the translated DPA. Refer to the memdev ABI entry at:
+		/sys/kernel/debug/cxl/memX/clear_poison for the detailed
+		behavior. This attribute is only visible if all memdevs
+		participating in the region support both inject and clear
+		poison commands.
+
+		TEST-ONLY INTERFACE: This interface is intended for testing
+		and validation purposes only. It is not a data repair mechanism
+		and should never be used on production systems or live data.
+
+		CLEAR IS NOT DATA RECOVERY: This operation writes zeros to the
+		specified address range and removes the address from the poison
+		list. It does NOT recover or restore original data that may have
+		been present before poison injection. Any original data at the
+		cleared address is permanently lost and replaced with zeros.
+
+		CLEAR IS NOT A REPAIR MECHANISM: This interface is for testing
+		purposes only and should not be used as a data repair tool.
+		Clearing poison is fundamentally different from data recovery
+		or error correction.
+
+What:		/sys/kernel/debug/cxl/einj_types
+Date:		January, 2024
+KernelVersion:	v6.9
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(RO) Prints the CXL protocol error types made available by
+		the platform in the format:
+
+			0x<error number> <error type>
+
+		The possible error types are (as of ACPI v6.5):
+
+			0x1000	CXL.cache Protocol Correctable
+			0x2000	CXL.cache Protocol Uncorrectable non-fatal
+			0x4000	CXL.cache Protocol Uncorrectable fatal
+			0x8000	CXL.mem Protocol Correctable
+			0x10000	CXL.mem Protocol Uncorrectable non-fatal
+			0x20000	CXL.mem Protocol Uncorrectable fatal
+
+		The <error number> can be written to einj_inject to inject
+		<error type> into a chosen dport.
+
+What:		/sys/kernel/debug/cxl/$dport_dev/einj_inject
+Date:		January, 2024
+KernelVersion:	v6.9
+Contact:	linux-cxl@vger.kernel.org
+Description:
+		(WO) Writing an integer to this file injects the corresponding
+		CXL protocol error into $dport_dev ($dport_dev will be a device
+		name from /sys/bus/pci/devices). The integer to type mapping for
+		injection can be found by reading from einj_types. If the dport
+		was enumerated in RCH mode, a CXL 1.1 error is injected, otherwise
+		a CXL 2.0 error is injected.