kernel/linux.git/fs/tracefs, branch master

Merge tag 'tracefs-v7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-22T22:09:01+00:00

Pull tracefs fixes from Steven Rostedt: - Use list_add_tail_rcu() for walking eventfs children The linked list of children is protected by SRCU and list walkers can walk the list with only using SRCU. Using just list_add_tail() on weakly ordered architectures can cause issues. Instead use list_add_tail_rcu(). - Hold eventfs_mutex and SRCU for remount walk events The trace_apply_options() walks the tracefs_inodes where some are eventfs inodes and eventfs_remount() is called which in turn calls eventfs_set_attr(). This walk only holds normal RCU read locks, but the eventfs_mutex and SRCU should be held. Add a eventfs_remount_(un)lock() helpers to take the necessary locks before iterating the list. * tag 'tracefs-v7.1-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: eventfs: Hold eventfs_mutex and SRCU when remount walks events eventfs: Use list_add_tail_rcu() for SRCU-protected children list

eventfs: Hold eventfs_mutex and SRCU when remount walks events

2026-04-18T23:15:00+00:00

Commit 340f0c7067a9 ("eventfs: Update all the eventfs_inodes from the events descriptor") had eventfs_set_attrs() recurse through ei->children on remount. The walk only holds the rcu_read_lock() taken by tracefs_apply_options() over tracefs_inodes, which is wrong: - list_for_each_entry over ei->children races with the list_del_rcu() in eventfs_remove_rec() -- LIST_POISON1 deref, same shape as d2603279c7d6. - eventfs_inodes are freed via call_srcu(&eventfs_srcu, ...). rcu_read_lock() does not extend an SRCU grace period, so ti->private can be reclaimed under the walk. - The writes to ei->attr race with eventfs_set_attr(), which holds eventfs_mutex. Reproducer: while :; do mount -o remount,uid=$((RANDOM%1000)) /sys/kernel/tracing; done & while :; do echo "p:kp submit_bio" > /sys/kernel/tracing/kprobe_events echo > /sys/kernel/tracing/kprobe_events done Wrap the events portion of tracefs_apply_options() in eventfs_remount_lock()/_unlock() that take eventfs_mutex and srcu_read_lock(&eventfs_srcu). eventfs_set_attrs() doesn't sleep so the nested rcu_read_lock() is fine; lockdep_assert_held() pins the contract. Comment in tracefs_drop_inode() said "RCU cycle" -- it is SRCU. Fixes: 340f0c7067a9 ("eventfs: Update all the eventfs_inodes from the events descriptor") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260418191737.10289-1-devnexen@gmail.com Signed-off-by: David Carlier Signed-off-by: Steven Rostedt

eventfs: Use list_add_tail_rcu() for SRCU-protected children list

2026-04-18T23:14:37+00:00

Commit d2603279c7d6 ("eventfs: Use list_del_rcu() for SRCU protected list variable") converted the removal side to pair with the list_for_each_entry_srcu() walker in eventfs_iterate(). The insertion in eventfs_create_dir() was left as a plain list_add_tail(), which on weakly-ordered architectures can expose a new entry to the SRCU reader before its list pointers and fields are observable. Use list_add_tail_rcu() so the publication pairs with the existing list_del_rcu() and list_for_each_entry_srcu(). Fixes: 43aa6f97c2d0 ("eventfs: Get rid of dentry pointers without refcounts") Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260418152251.199343-1-devnexen@gmail.com Signed-off-by: David Carlier Signed-off-by: Steven Rostedt

Merge tag 'tracefs-v7.1-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace

2026-04-15T23:27:32+00:00

Pull tracefs updates from Steven Rostedt: - Simplify error handling with guards() Use guards() to simplify the handling of releasing locks in exit paths. - Use dentry name snapshots instead of allocation Instead of allocating a temp buffer to store the dentry name to use in mkdir() and rmdir() use take_dentry_name_snapshot(). - Fix default permissions not being applied at boot The default permissions for tracefs was 0700 to only allow root having access. But after a change to fix other mount options the update to permissions ignored the defined default and used the system default of 0755. This is a regression and is fixed. * tag 'tracefs-v7.1-v2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace: tracefs: Removed unused 'ret' variable in eventfs_iterate() tracefs: Fix default permissions not being applied on initial mount tracefs: Use dentry name snapshots instead of heap allocation eventfs: Simplify code using guard()s

tracefs: Removed unused 'ret' variable in eventfs_iterate()

2026-04-14T15:08:24+00:00

Moving to guard() usage removed the need of using the 'ret' variable but it wasn't removed. As it was set to zero, the compiler in use didn't warn (although some compilers do). Cc: Masami Hiramatsu Cc: Mathieu Desnoyers Link: https://patch.msgid.link/20260414110344.75c0663f@robin Fixes: 4d9b262031f ("eventfs: Simplify code using guard()s") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202604100111.AAlbQKmK-lkp@intel.com/ Signed-off-by: Steven Rostedt (Google)

tracefs: Fix default permissions not being applied on initial mount

2026-04-08T20:15:09+00:00

Commit e4d32142d1de ("tracing: Fix tracefs mount options") moved the option application from tracefs_fill_super() to tracefs_reconfigure() called from tracefs_get_tree(). This fixed mount options being ignored on user-space mounts when the superblock already exists, but introduced a regression for the initial kernel-internal mount. On the first mount (via simple_pin_fs during init), sget_fc() transfers fc->s_fs_info to sb->s_fs_info and sets fc->s_fs_info to NULL. When tracefs_get_tree() then calls tracefs_reconfigure(), it sees a NULL fc->s_fs_info and returns early without applying any options. The root inode keeps mode 0755 from simple_fill_super() instead of the intended TRACEFS_DEFAULT_MODE (0700). Furthermore, even on subsequent user-space mounts without an explicit mode= option, tracefs_apply_options(sb, true) gates the mode behind fsi->opts & BIT(Opt_mode), which is unset for the defaults. So the mode is never corrected unless the user explicitly passes mode=0700. Restore the tracefs_apply_options(sb, false) call in tracefs_fill_super() to apply default permissions on initial superblock creation, matching what debugfs does in debugfs_fill_super(). Cc: stable@vger.kernel.org Fixes: e4d32142d1de ("tracing: Fix tracefs mount options") Link: https://patch.msgid.link/20260404134747.98867-1-devnexen@gmail.com Signed-off-by: David Carlier Signed-off-by: Steven Rostedt (Google)

tracefs: Use dentry name snapshots instead of heap allocation

2026-03-24T21:04:58+00:00

In fs/tracefs/inode.c, tracefs_syscall_mkdir() and tracefs_syscall_rmdir() previously used a local helper, get_dname(), which allocated a temporary buffer on the heap via kmalloc() to hold the dentry name. This introduced unnecessary overhead, an ENOMEM failure path, and required manual memory cleanup via kfree(). As suggested by Al Viro, replace this heap allocation with the VFS dentry name snapshot API. By stack-allocating a `struct name_snapshot` and using take_dentry_name_snapshot() and release_dentry_name_snapshot(), we safely capture the dentry name locklessly, eliminate the heap allocation entirely, and remove the now-obsolete error handling paths. The get_dname() helper is completely removed. Testing: Booted a custom kernel natively in virtme-ng (ARM64). Triggered tracefs inode and dentry allocation by creating and removing a custom directory under a temporary tracefs mount. Verified that the instance is created successfully and that no memory errors or warnings are emitted in dmesg. Link: https://patch.msgid.link/20260306200458.2264-1-anishm7030@gmail.com Suggested-by: Al Viro Signed-off-by: AnishMulay Signed-off-by: Steven Rostedt (Google)

eventfs: Simplify code using guard()s

2026-03-24T21:03:38+00:00

Use guard(mutex), scoped_guard(mutex) and guard(src) to simplify the code and remove a lot of the jumps to "out:" labels. Cc: Mathieu Desnoyers Link: https://lore.kernel.org/20250604151625.250d13e1@gandalf.local.home Signed-off-by: Steven Rostedt (Google) Reviewed-by: Masami Hiramatsu (Google)

tracing: Add a trace remote module for testing

2026-03-09T16:33:55+00:00

Add a module to help testing the tracefs support for trace remotes. This module: * Use simple_ring_buffer to write into a ring-buffer. * Declare a single "selftest" event that can be triggered from user-space. * Register a "test" trace remote. This is intended to be used by trace remote selftests. Link: https://patch.msgid.link/20260309162516.2623589-15-vdonnefort@google.com Reviewed-by: Steven Rostedt (Google) Signed-off-by: Vincent Donnefort Signed-off-by: Steven Rostedt (Google)

Convert 'alloc_obj' family to use the new default GFP_KERNEL argument

2026-02-22T01:09:51+00:00

This was done entirely with mindless brute force, using git grep -l '\