kernel/linux.git/lib/ref_tracker.c, branch v6.19.11

ref_tracker: remove redundant __GFP_NOWARN

2025-09-14T00:32:43+00:00

Commit 16f5dfbc851b ("gfp: include __GFP_NOWARN in GFP_NOWAIT") made GFP_NOWAIT implicitly include __GFP_NOWARN. Therefore, explicit __GFP_NOWARN combined with GFP_NOWAIT (e.g., `GFP_NOWAIT | __GFP_NOWARN`) is now redundant. Let's clean up these redundant flags across subsystems. No functional changes. Link: https://lkml.kernel.org/r/20250805023031.331718-1-rongqianfeng@vivo.com Signed-off-by: Qianfeng Rong Cc: Matthew Wilcox (Oracle) Signed-off-by: Andrew Morton

ref_tracker: use %p instead of %px in debugfs dentry name

2025-08-12T03:07:44+00:00

As Kees points out, this is a kernel address leak, and debugging is not a sufficiently good reason to expose the real kernel address. Fixes: 65b584f53611 ("ref_tracker: automatically register a file in debugfs for a ref_tracker_dir") Reported-by: Kees Cook Closes: https://lore.kernel.org/netdev/202507301603.62E553F93@keescook/ Signed-off-by: Jeff Layton Reviewed-by: Eric Dumazet Signed-off-by: Jakub Kicinski

ref_tracker: do xarray and workqueue job initializations earlier

2025-06-27T20:20:29+00:00

The kernel test robot reported an oops that occurred when attempting to deregister a dentry from the xarray during subsys_initcall(). The ref_tracker xarrays and workqueue job are being initialized in late_initcall() which is too late. Move those to postcore_initcall() instead. Fixes: 65b584f53611 ("ref_tracker: automatically register a file in debugfs for a ref_tracker_dir") Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-lkp/202506251406.c28f2adb-lkp@intel.com Signed-off-by: Jeff Layton Signed-off-by: Jakub Kicinski Link: https://patch.msgid.link/20250626-reftrack-dbgfs-v1-1-812102e2a394@kernel.org

ref_tracker: eliminate the ref_tracker_dir name field

2025-06-20T00:02:04+00:00

Now that we have dentries and the ability to create meaningful symlinks to them, don't keep a name string in each tracker. Switch the output format to print "class@address", and drop the name field. Also, add a kerneldoc header for ref_tracker_dir_init(). Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-9-24fc37ead144@kernel.org Signed-off-by: Jakub Kicinski

ref_tracker: add a way to create a symlink to the ref_tracker_dir debugfs file

2025-06-20T00:02:04+00:00

Add the ability for a subsystem to add a user-friendly symlink that points to a ref_tracker_dir's debugfs file. Add a separate debugfs_symlinks xarray and use that to track symlinks. The reaper workqueue job will remove symlinks before their corresponding dentries. Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-7-24fc37ead144@kernel.org Signed-off-by: Jakub Kicinski

ref_tracker: automatically register a file in debugfs for a ref_tracker_dir

2025-06-20T00:02:04+00:00

Currently, there is no convenient way to see the info that the ref_tracking infrastructure collects. Attempt to create a file in debugfs when called from ref_tracker_dir_init(). The file is given the name "class@%px", as having the unmodified address is helpful for debugging. This should be safe since this directory is only accessible by root While ref_tracker_dir_init() is generally called from a context where sleeping is OK, ref_tracker_dir_exit() can be called from anywhere. Thus, dentry cleanup must be handled asynchronously. Add a new global xarray that has entries with the ref_tracker_dir pointer as the index and the corresponding debugfs dentry pointer as the value. Instead of removing the debugfs dentry, have ref_tracker_dir_exit() set a mark on the xarray entry and schedule a workqueue job. The workqueue job then walks the xarray looking for marked entries, and removes their xarray entries and the debugfs dentries. Because of this, the debugfs dentry can outlive the corresponding ref_tracker_dir. Have ref_tracker_debugfs_show() take extra care to ensure that it's safe to dereference the dir pointer before using it. Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-6-24fc37ead144@kernel.org Signed-off-by: Jakub Kicinski

ref_tracker: allow pr_ostream() to print directly to a seq_file

2025-06-20T00:02:04+00:00

Allow pr_ostream to also output directly to a seq_file without an intermediate buffer. The first caller of +ref_tracker_dir_seq_print() will come in a later patch, so mark that __maybe_unused for now. That designation will be removed once it is used. Reviewed-by: Andrew Lunn Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-5-24fc37ead144@kernel.org Signed-off-by: Jakub Kicinski

ref_tracker: have callers pass output function to pr_ostream()

2025-06-20T00:02:03+00:00

In a later patch, we'll be adding a 3rd mechanism for outputting ref_tracker info via seq_file. Instead of a conditional, have the caller set a pointer to an output function in struct ostream. As part of this, the log prefix must be explicitly passed in, as it's too late for the pr_fmt macro. Reviewed-by: Andrew Lunn Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-3-24fc37ead144@kernel.org Signed-off-by: Jakub Kicinski

ref_tracker: add a top level debugfs directory for ref_tracker

2025-06-20T00:02:03+00:00

Add a new "ref_tracker" directory in debugfs. Each individual refcount tracker can register files under there to display info about currently-held references. Reviewed-by: Andrew Lunn Reviewed-by: Krzysztof Karas Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-2-24fc37ead144@kernel.org Signed-off-by: Jakub Kicinski

ref_tracker: don't use %pK in pr_ostream() output

2025-06-20T00:02:03+00:00

As Thomas Weißschuh points out [1], it is now preferable to use %p instead of hashed pointers with printk(), since raw pointers should no longer be leaked into the kernel log. Change the ref_tracker infrastructure to use %p instead of %pK in its formats. [1]: https://lore.kernel.org/netdev/20250414-restricted-pointers-net-v1-0-12af0ce46cdd@linutronix.de/ Reviewed-by: Thomas Weißschuh Reviewed-by: Krzysztof Karas Signed-off-by: Jeff Layton Link: https://patch.msgid.link/20250618-reftrack-dbgfs-v15-1-24fc37ead144@kernel.org Signed-off-by: Jakub Kicinski