Merge tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Don't destroy user event fields when removal fails

   User event fields are destroyed before the event is removed from
   visibility. But that can fail leaving the still visible event with no
   fields. Move the destroying of the fields to after the event is
   successfully removed from visibility.

 - Initialize function graph state is fork before calling
   copy_exec_state()

   For non-CLONE_VM forks, copy_exec_state() allocates a new
   task_exec_state. If that allocation fails, ftrace_graph_exit_task()
   will free the tasks ret_stack pointer. Since that pointer is still
   using the parent's ret_stack, it mistakenly frees the parent's
   pointer too.

   Call ftrace_graph_init() on the task first which will NULL out the
   new tasks's ret_stack and if the copy fails, it will not free
   anything.

 - Remove FGRAPH_MAX_INDEX

   The macro FGRAPH_MAX_INDEX was added but never used. Remove it.

 - Save ent_size in function graph printing of nested functions

   The function graph tracer needs to look at the next event to see if
   the next event is the return of the current function entry. If it is,
   it prints a single line:

	ktime_get();

   Otherwise it prints it like a nested function:

	tick_nohz_irq_exit() {
	    ktime_get();
	    kcpustat_irq_exit();
	}

   In order to look at the next event, it must save the current event so
   that it has the information to print from it. It saves the event in
   the iterator descriptor called "ent". What it doesn't save is the
   ent_size of the event which is now used to know if the function graph
   arguments are to be printed. The peek doesn't save the size so the
   size used happens to be that of the size of the last event that was
   seen.

   Save the entry event size in the iterator descriptor so that the
   correct size is used.

 - Fix several errors with freeing data in the histogram code

   The histogram code had a lot of leaked or or incorrect accounting
   when failures happen. Correct them.

 - Fix histogram regression of .percent and .graph modifiers

   Up until 6.3 histogram values could have "percent" or "graph"
   modifiers that changed how they were printed. But a change that added
   restricting histograms values from being strings, stack traces and
   other modifiers inadvertently prevented them from using the percent
   and graph modifiers, which were legal use cases for values.

   Put back the percent and graph modifiers.

 - Fix various typos in the comments

 - Set the trace_clock before initializing a histogram with clock
   argument

   The histogram API allows the user to specific which trace clock to
   use via a "clock=" string. The histogram is set up first before the
   clock is checked. If the passed in clock is not valid, it exits
   without fully fixing up the histogram leaving it on the list and a
   use-after-free can trigger.

   Update the clock argument first and if it fails then exit gracefully
   before the histogram trigger is placed on any lists.

 - Restore :mod: trailer after parsing in ftrace_set_clr_event

   The function ftrace_set_clr_event() modifies the parse string and
   needs to put it back to what was passed in. It searches for ":mod:"
   via a strsep() but fails to put back the first ':' in the string.

   Add back the ':' in the passed in string.

 - Take trace_array reference when opening a tracer options file

   The options files are dynamically created and some tracers add their
   own options. When a tracer adds their own list of options, the
   trace_array holding them has an array to hold the list of options for
   each tracer. This array increases in size via a krealloc(), and the
   new entry gets a newly allocated array to hold the options of the new
   tracer being added.

   The element in each entry of the tracer's option array holds a
   pointer back to the trace_array, a pointer to the tracer it is
   associated to, a pointer to the flags of the option.

   The issue is that these arrays are freed when the trace_array is
   freed when its instance it represents is removed from the instances
   directory. There's a race that an open of one of these options files
   can happen when the instance is being removed.

   Add a new helper function to be called by the open function of the
   options file to iterate all existing trace_arrays under a lock and
   find the one that has the given option element in one of it's tracer
   arrays. If found, then update the associated trace_array's reference
   counter to keep it from being freed. If not found, have the open call
   return -ENODEV.

 - Disable interrupts when acquiring the lock in rb_wake_up_waiters()

   The function rb_wake_up_waiters() assumes it will be called in
   interrupt context and does not disable irqs when taking
   cpu_buffer->reader_lock, which can be called in hard interrupt
   context. The issue is in PREEMPT_RT, this function is called in
   thread context leaving this lock open to a deadlock.

   Take the lock with interrupts disabled.

 - Use rcu_assign_pointer() for tmp_ops filter hash

   The tmp_ops used in update_ftrace_direct_mod() assigns its
   filter_hash field directly, but that field is annotated as __rcu and
   sparse complains. Assign it with rcu_assign_pointer()

 - Fix use-after-free in enable_trigger_private_data_free()

   The trace_event_call is accessed through the event_trigger_data's
   trace_event_file pointer to put the trace_event_call on freeing. The
   issue is that the trace_event_file data may have been freed already
   causing a use-after-free. Add a field to the event_trigger_data that
   points directly to the trace_event_call so that it can decrement its
   reference directly without needing to go through the
   trace_event_file.

 - Fix accounting of buffer data remote headers

   trace_buffer_desc_size() and trace_remote_alloc_buffer() undercount
   the number of pages is needed for the asked for size as it doesn't
   take into account the meta data on each page. Add a helper function
   to do the calculation properly and use that in these functions.

 - Catch nr_page_va overflow in ring_buffer_desc sizing

   The number of pages per remote ring buffer is capped by
   ring_buffer_desc::nr_page_va (32 bits). A buffer_size large enough to
   overflow that field would silently allocate a descriptor smaller than
   what was asked for.

 - Do not resize the subbuf order if any per_cpu buffer is disabled

   The mmapping of ring buffers disables resizing the subbuffers, but it
   is done per-cpu whereas the subbuf size change is done for all the
   per_cpu buffers under the buffer->mutex. It could change the size of
   some while the mapping is happening on others. Have the resize of the
   subbuf order check all the per_cpu buffers under the lock to see if
   any of them is disabled before starting and causing an inconsistency
   between buffers that are being mapped.

* tag 'trace-v7.3-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: (25 commits)
  ring-buffer: Check resize_disabled before publishing the new subbuf order
  tracing/remotes: Catch nr_page_va overflow in ring_buffer_desc sizing
  tracing/remotes: Account for ring buffer page header in size calculation
  tracing: Don't dereference trace_event_file in deferred trigger free
  ftrace: Use rcu_assign_pointer() for tmp_ops filter hash
  ring-buffer: Acquire the lock with irqsave in rb_wake_up_waiters()
  tracing: Take trace_array reference when opening a tracer options file
  tracing: Fix ring_buffer_read_page_size() kernel-doc
  tracing: Restore :mod: trailer after parsing in ftrace_set_clr_event()
  tracing: Fix memory corruption from a "STACKTRACE" histogram key
  tracing: Fix memory corruption from the histogram stacktrace modifier
  tracing: Undo the registration when enabling the histogram trigger fails
  tracing: Take the reference before publishing the named histogram trigger
  tracing: Set the trace clock before registering the histogram trigger
  tracing: Fix typo "preceeded" in comment
  tracing: Fix typo "availabe" in comment
  tracing: Let histogram values keep the percent and graph modifiers
  tracing: Keep the entry count when the histogram stats allocation fails
  tracing: Free histogram the field rejected for a bad modifier
  tracing: Free histogram the var ref when its initialization fails
  ...

1 files changed, 409 insertions, 0 deletions

diff --git a/drivers/dax/fsdev.c b/drivers/dax/fsdev.c
new file mode 100644
index 000000000..598604bf5
--- /dev/null
+++ b/drivers/dax/fsdev.c
@@ -0,0 +1,409 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright(c) 2026 Micron Technology, Inc. */
+#include <linux/memremap.h>
+#include <linux/pagemap.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/cdev.h>
+#include <linux/slab.h>
+#include <linux/dax.h>
+#include <linux/uio.h>
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include "dax-private.h"
+#include "bus.h"
+
+/*
+ * FS-DAX compatible devdax driver
+ *
+ * Unlike drivers/dax/device.c which pre-initializes compound folios based
+ * on device alignment (via vmemmap_shift), this driver leaves folios
+ * uninitialized similar to pmem. This allows fs-dax filesystems like famfs
+ * to work without needing special handling for pre-initialized folios.
+ *
+ * Key differences from device.c:
+ * - pgmap type is MEMORY_DEVICE_FS_DAX (not MEMORY_DEVICE_GENERIC)
+ * - vmemmap_shift is NOT set (folios remain order-0)
+ * - fs-dax can dynamically create compound folios as needed
+ * - No mmap support - all access is through fs-dax/iomap
+ */
+
+static void fsdev_write_dax(void *addr, struct page *page,
+		unsigned int off, unsigned int len)
+{
+	while (len) {
+		void *mem = kmap_local_page(page);
+		unsigned int chunk = min_t(unsigned int, len, PAGE_SIZE - off);
+
+		memcpy_flushcache(addr, mem + off, chunk);
+		kunmap_local(mem);
+		len -= chunk;
+		off = 0;
+		page++;
+		addr += chunk;
+	}
+}
+
+static long __fsdev_dax_direct_access(struct dax_device *dax_dev, pgoff_t pgoff,
+		long nr_pages, enum dax_access_mode mode, void **kaddr,
+		unsigned long *pfn)
+{
+	struct dev_dax *dev_dax = dax_get_private(dax_dev);
+	size_t size = nr_pages << PAGE_SHIFT;
+	size_t offset = pgoff << PAGE_SHIFT;
+	phys_addr_t phys;
+
+	phys = dax_pgoff_to_phys(dev_dax, pgoff, size);
+	if (phys == -1) {
+		dev_dbg(&dev_dax->dev,
+			"pgoff (%#lx) out of range\n", pgoff);
+		return -EFAULT;
+	}
+
+	if (kaddr)
+		*kaddr = __va(phys);
+
+	if (pfn)
+		*pfn = PHYS_PFN(phys);
+
+	/*
+	 * Use cached_size which was computed at probe time. The size cannot
+	 * change while the driver is bound (resize returns -EBUSY).
+	 */
+	return PHYS_PFN(min(size, dev_dax->cached_size - offset));
+}
+
+static int fsdev_dax_zero_page_range(struct dax_device *dax_dev,
+			pgoff_t pgoff, size_t nr_pages)
+{
+	void *kaddr;
+	long rc;
+
+	WARN_ONCE(nr_pages > 1, "%s: nr_pages > 1\n", __func__);
+	rc = __fsdev_dax_direct_access(dax_dev, pgoff, 1, DAX_ACCESS,
+				       &kaddr, NULL);
+	if (rc < 0)
+		return rc;
+	fsdev_write_dax(kaddr, ZERO_PAGE(0), 0, PAGE_SIZE);
+	return 0;
+}
+
+static long fsdev_dax_direct_access(struct dax_device *dax_dev,
+		pgoff_t pgoff, long nr_pages, enum dax_access_mode mode,
+		void **kaddr, unsigned long *pfn)
+{
+	return __fsdev_dax_direct_access(dax_dev, pgoff, nr_pages, mode,
+					 kaddr, pfn);
+}
+
+static size_t fsdev_dax_recovery_write(struct dax_device *dax_dev,
+		pgoff_t pgoff, void *addr, size_t bytes, struct iov_iter *i)
+{
+	return _copy_from_iter_flushcache(addr, bytes, i);
+}
+
+static const struct dax_operations dev_dax_ops = {
+	.direct_access = fsdev_dax_direct_access,
+	.zero_page_range = fsdev_dax_zero_page_range,
+	.recovery_write = fsdev_dax_recovery_write,
+};
+
+static void fsdev_cdev_del(void *cdev)
+{
+	cdev_del(cdev);
+}
+
+static void fsdev_kill(void *dev_dax)
+{
+	kill_dev_dax(dev_dax);
+}
+
+static void fsdev_clear_ops(void *data)
+{
+	struct dev_dax *dev_dax = data;
+
+	dax_set_ops(dev_dax->dax_dev, NULL);
+}
+
+static void fsdev_clear_pgmap_ops(void *data)
+{
+	struct dev_pagemap *pgmap = data;
+
+	/*
+	 * fsdev installs pgmap->ops and ->owner at probe. For a static device
+	 * the pgmap is shared and long-lived (owned by the dax bus), so
+	 * leaving fsdev's ops behind on unbind would let a later
+	 * memory_failure -- after rebind to another driver, or after this
+	 * module is unloaded -- dispatch through a stale or freed
+	 * ->memory_failure handler. Clear them so the pgmap carries no fsdev
+	 * state once we are unbound.
+	 */
+	pgmap->ops = NULL;
+	pgmap->owner = NULL;
+}
+
+/*
+ * Page map operations for FS-DAX mode
+ * Similar to fsdax_pagemap_ops in drivers/nvdimm/pmem.c
+ *
+ * Note: folio_free callback is not needed for MEMORY_DEVICE_FS_DAX.
+ * The core mm code in free_zone_device_folio() handles the wake_up_var()
+ * directly for this memory type.
+ */
+static u64 fsdev_pfn_to_offset(struct dev_dax *dev_dax, unsigned long pfn)
+{
+	phys_addr_t phys = PFN_PHYS(pfn);
+	u64 offset = 0;
+
+	for (int i = 0; i < dev_dax->nr_range; i++) {
+		struct range *range = &dev_dax->ranges[i].range;
+
+		if (phys >= range->start && phys <= range->end)
+			return offset + (phys - range->start);
+		offset += range_len(range);
+	}
+	return -1ULL;
+}
+
+static int fsdev_pagemap_memory_failure(struct dev_pagemap *pgmap,
+		unsigned long pfn, unsigned long nr_pages, int mf_flags)
+{
+	struct dev_dax *dev_dax = pgmap->owner;
+	u64 offset = fsdev_pfn_to_offset(dev_dax, pfn);
+	u64 len = nr_pages << PAGE_SHIFT;
+
+	return dax_holder_notify_failure(dev_dax->dax_dev, offset,
+					 len, mf_flags);
+}
+
+static const struct dev_pagemap_ops fsdev_pagemap_ops = {
+	.memory_failure		= fsdev_pagemap_memory_failure,
+};
+
+/*
+ * Clear any stale folio state from pages in the given range.
+ * This is necessary because device_dax pre-initializes compound folios
+ * based on vmemmap_shift, and that state may persist after driver unbind.
+ * Since fsdev_dax uses MEMORY_DEVICE_FS_DAX without vmemmap_shift, fs-dax
+ * expects to find clean order-0 folios that it can build into compound
+ * folios on demand.
+ *
+ * At probe time, no filesystem should be mounted yet, so all mappings
+ * are stale and must be cleared along with compound state.
+ */
+static void fsdev_clear_folio_state(struct dev_dax *dev_dax)
+{
+	for (int i = 0; i < dev_dax->nr_range; i++) {
+		struct range *range = &dev_dax->ranges[i].range;
+		unsigned long pfn = PHYS_PFN(range->start);
+		unsigned long end_pfn = PHYS_PFN(range->end) + 1;
+
+		while (pfn < end_pfn) {
+			struct folio *folio = pfn_folio(pfn);
+			int order = dax_folio_reset_order(folio);
+
+			pfn += 1UL << order;
+		}
+	}
+}
+
+static void fsdev_clear_folio_state_action(void *data)
+{
+	fsdev_clear_folio_state(data);
+}
+
+static int fsdev_open(struct inode *inode, struct file *filp)
+{
+	struct dax_device *dax_dev = inode_dax(inode);
+	struct dev_dax *dev_dax = dax_get_private(dax_dev);
+
+	filp->private_data = dev_dax;
+
+	return 0;
+}
+
+static int fsdev_release(struct inode *inode, struct file *filp)
+{
+	return 0;
+}
+
+static const struct file_operations fsdev_fops = {
+	.llseek = noop_llseek,
+	.owner = THIS_MODULE,
+	.open = fsdev_open,
+	.release = fsdev_release,
+};
+
+/*
+ * Acquire the dev_pagemap for probe: the static (pre-populated) one if
+ * present, or a devm-allocated one for the dynamic case. Note that
+ * dev_dax->pgmap is not set here; fsdev_dax_probe() sets it only once
+ * probe succeeds, so a failed probe never leaves a dangling pointer
+ * to a devres-freed pgmap.
+ */
+static struct dev_pagemap *fsdev_acquire_pgmap(struct dev_dax *dev_dax)
+{
+	struct device *dev = &dev_dax->dev;
+	struct dev_pagemap *pgmap;
+	size_t pgmap_size;
+
+	if (static_dev_dax(dev_dax)) {
+		if (dev_dax->nr_range > 1) {
+			dev_warn(dev,
+				 "static pgmap / multi-range device conflict\n");
+			return ERR_PTR(-EINVAL);
+		}
+
+		pgmap = dev_dax->pgmap;
+		pgmap->vmemmap_shift = 0;
+		return pgmap;
+	}
+
+	if (dev_dax->pgmap) {
+		dev_warn(dev, "dynamic-dax with pre-populated page map\n");
+		return ERR_PTR(-EINVAL);
+	}
+
+	pgmap_size = struct_size(pgmap, ranges, dev_dax->nr_range - 1);
+	pgmap = devm_kzalloc(dev, pgmap_size, GFP_KERNEL);
+	if (!pgmap)
+		return ERR_PTR(-ENOMEM);
+
+	pgmap->nr_range = dev_dax->nr_range;
+	for (int i = 0; i < dev_dax->nr_range; i++)
+		pgmap->ranges[i] = dev_dax->ranges[i].range;
+
+	return pgmap;
+}
+
+static int fsdev_dax_probe(struct dev_dax *dev_dax)
+{
+	struct dax_device *dax_dev = dev_dax->dax_dev;
+	struct device *dev = &dev_dax->dev;
+	struct dev_pagemap *pgmap;
+	struct inode *inode;
+	u64 data_offset = 0;
+	struct cdev *cdev;
+	void *addr;
+	int rc, i;
+
+	pgmap = fsdev_acquire_pgmap(dev_dax);
+	if (IS_ERR(pgmap))
+		return PTR_ERR(pgmap);
+
+	for (i = 0; i < dev_dax->nr_range; i++) {
+		struct range *range = &dev_dax->ranges[i].range;
+
+		if (!devm_request_mem_region(dev, range->start,
+					range_len(range), dev_name(dev))) {
+			dev_warn(dev, "mapping%d: %#llx-%#llx could not reserve range\n",
+				 i, range->start, range->end);
+			return -EBUSY;
+		}
+	}
+
+	/* Cache size now; it cannot change while driver is bound */
+	dev_dax->cached_size = 0;
+	for (i = 0; i < dev_dax->nr_range; i++)
+		dev_dax->cached_size += range_len(&dev_dax->ranges[i].range);
+
+	/*
+	 * Use MEMORY_DEVICE_FS_DAX without setting vmemmap_shift, leaving
+	 * folios at order-0. Unlike device.c (MEMORY_DEVICE_GENERIC), this
+	 * lets fs-dax dynamically build compound folios as needed, similar
+	 * to pmem behavior.
+	 */
+	pgmap->type = MEMORY_DEVICE_FS_DAX;
+	pgmap->ops = &fsdev_pagemap_ops;
+	pgmap->owner = dev_dax;
+
+	addr = devm_memremap_pages(dev, pgmap);
+	if (IS_ERR(addr))
+		return PTR_ERR(addr);
+
+	/* Drop fsdev's pgmap->ops/owner on unbind so no stale ops survive. */
+	rc = devm_add_action_or_reset(dev, fsdev_clear_pgmap_ops, pgmap);
+	if (rc)
+		return rc;
+
+	/*
+	 * Clear any stale compound folio state left over from a previous
+	 * driver (e.g., device_dax with vmemmap_shift). Also register this
+	 * as a devm action so folio state is cleared on unbind, ensuring
+	 * clean pages for subsequent drivers (e.g., kmem for system-ram).
+	 */
+	fsdev_clear_folio_state(dev_dax);
+	rc = devm_add_action_or_reset(dev, fsdev_clear_folio_state_action,
+				      dev_dax);
+	if (rc)
+		return rc;
+
+	/* Detect whether the data is at a non-zero offset into the memory */
+	if (pgmap->range.start != dev_dax->ranges[0].range.start) {
+		u64 phys = dev_dax->ranges[0].range.start;
+		u64 pgmap_phys = pgmap[0].range.start;
+
+		if (pgmap_phys > phys) {
+			dev_err(dev, "pgmap start %#llx exceeds data start %#llx\n",
+				pgmap_phys, phys);
+			return -EINVAL;
+		}
+		data_offset = phys - pgmap_phys;
+
+		pr_debug("%s: offset detected phys=%llx pgmap_phys=%llx offset=%llx\n",
+		       __func__, phys, pgmap_phys, data_offset);
+	}
+
+	inode = dax_inode(dax_dev);
+	cdev = inode->i_cdev;
+	cdev_init(cdev, &fsdev_fops);
+	cdev->owner = dev->driver->owner;
+	cdev_set_parent(cdev, &dev->kobj);
+	rc = cdev_add(cdev, dev->devt, 1);
+	if (rc)
+		return rc;
+
+	rc = devm_add_action_or_reset(dev, fsdev_cdev_del, cdev);
+	if (rc)
+		return rc;
+
+	/* Set the dax operations for fs-dax access path */
+	rc = dax_set_ops(dax_dev, &dev_dax_ops);
+	if (rc)
+		return rc;
+
+	rc = devm_add_action_or_reset(dev, fsdev_clear_ops, dev_dax);
+	if (rc)
+		return rc;
+
+	run_dax(dax_dev);
+	rc = devm_add_action_or_reset(dev, fsdev_kill, dev_dax);
+	if (rc)
+		return rc;
+
+	/* Probe can no longer fail; expose the pgmap via dev_dax */
+	dev_dax->pgmap = pgmap;
+	return 0;
+}
+
+static struct dax_device_driver fsdev_dax_driver = {
+	.probe = fsdev_dax_probe,
+	.type = DAXDRV_FSDEV_TYPE,
+};
+
+static int __init dax_init(void)
+{
+	return dax_driver_register(&fsdev_dax_driver);
+}
+
+static void __exit dax_exit(void)
+{
+	dax_driver_unregister(&fsdev_dax_driver);
+}
+
+MODULE_AUTHOR("John Groves");
+MODULE_DESCRIPTION("FS-DAX Device: fs-dax compatible devdax driver");
+MODULE_LICENSE("GPL");
+module_init(dax_init);
+module_exit(dax_exit);
+MODULE_ALIAS_DAX_DEVICE(0);