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, 134 insertions, 0 deletions

diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi
new file mode 100644
index 000000000..0d2abd88a
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-class-bdi
@@ -0,0 +1,134 @@
+What:		/sys/class/bdi/<bdi>/
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+
+Provide a place in sysfs for the backing_dev_info object.  This allows
+setting and retrieving various BDI specific variables.
+
+The <bdi> identifier can be either of the following:
+
+MAJOR:MINOR
+
+	Device number for block devices, or value of st_dev on
+	non-block filesystems which provide their own BDI, such as NFS
+	and FUSE.
+
+MAJOR:MINOR-fuseblk
+
+	Value of st_dev on fuseblk filesystems.
+
+default
+
+	The default backing dev, used for non-block device backed
+	filesystems which do not provide their own BDI.
+
+What:		/sys/class/bdi/<bdi>/read_ahead_kb
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+	Size of the read-ahead window in kilobytes
+
+	(read-write)
+What:		/sys/class/bdi/<bdi>/min_ratio
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+	Under normal circumstances each device is given a part of the
+	total write-back cache that relates to its current average
+	writeout speed in relation to the other devices.
+
+	The 'min_ratio' parameter allows assigning a minimum
+	percentage of the write-back cache to a particular device.
+	For example, this is useful for providing a minimum QoS.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/min_ratio_fine
+Date:		November 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Under normal circumstances each device is given a part of the
+	total write-back cache that relates to its current average
+	writeout speed in relation to the other devices.
+
+	The 'min_ratio_fine' parameter allows assigning a minimum reserve
+	of the write-back cache to a particular device. The value is
+	expressed as part of 1 million. For example, this is useful for
+	providing a minimum QoS.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/max_ratio
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+	Allows limiting a particular device to use not more than the
+	given percentage of the write-back cache.  This is useful in
+	situations where we want to avoid one device taking all or
+	most of the write-back cache.  For example in case of an NFS
+	mount that is prone to get stuck, or a FUSE mount which cannot
+	be trusted to play fair.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/max_ratio_fine
+Date:		November 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Allows limiting a particular device to use not more than the
+	given value of the write-back cache.  The value is given as part
+	of 1 million. This is useful in situations where we want to avoid
+	one device taking all or most of the write-back cache.  For example
+	in case of an NFS mount that is prone to get stuck, or a FUSE mount
+	which cannot be trusted to play fair.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/min_bytes
+Date:		October 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Under normal circumstances each device is given a part of the
+	total write-back cache that relates to its current average
+	writeout speed in relation to the other devices.
+
+	The 'min_bytes' parameter allows assigning a minimum
+	percentage of the write-back cache to a particular device
+	expressed in bytes.
+	For example, this is useful for providing a minimum QoS.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/max_bytes
+Date:		October 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Allows limiting a particular device to use not more than the
+	given 'max_bytes' of the write-back cache.  This is useful in
+	situations where we want to avoid one device taking all or
+	most of the write-back cache.  For example in case of an NFS
+	mount that is prone to get stuck, a FUSE mount which cannot be
+	trusted to play fair, or a nbd device.
+
+	(read-write)
+
+What:		/sys/class/bdi/<bdi>/strict_limit
+Date:		October 2022
+Contact:	Stefan Roesch <shr@devkernel.io>
+Description:
+	Forces per-BDI checks for the share of given device in the write-back
+	cache even before the global background dirty limit is reached. This
+	is useful in situations where the global limit is much higher than
+	affordable for given relatively slow (or untrusted) device. Turning
+	strictlimit on has no visible effect if max_ratio is equal to 100%.
+
+	(read-write)
+What:		/sys/class/bdi/<bdi>/stable_pages_required
+Date:		January 2008
+Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
+Description:
+	If set, the backing device requires that all pages comprising a write
+	request must not be changed until writeout is complete.
+
+	(read-only)