[RFC PATCH 0/3] alloc_tag: fix races and a leak around shutdown_mem_profiling()

Three fixes for races and a leak in how allocation profiling meets the
module loader, reported by sashiko.

  1. percpu counter leak on modules loaded after profiling is disabled.
  2. layout/move TOCTOU that can silently overwrite module memory when
     profiling disabled between layout_sections() and move_module().
     Additionally, the retry logic here depends on [1].
  3. AB-BA deadlock between module load and /proc/allocinfo readers.

Patch 1 adds CODETAG_MODULE_EXCLUDED so profiling-disabled modules are
dropped from the tag list instead of half-registered, and frees the
section reservation unconditionally on unload. Patch 2 makes
layout_sections() the sole authority for codetag placement. Patch 3
defers remove_proc_entry() to a workqueue.

Feedback and suggestions are warmly welcomed; I would greatly appreciate
any input.

Remaining sashiko-reported bugs will be fixed in follow-up patches.

[1]: https://lore.kernel.org/all/[email protected]/

Hao Ge (3):
  alloc_tag: skip percpu counter allocation when profiling is disabled
  module: move codetag section placement decision to layout_sections()
  alloc_tag: remove /proc/allocinfo outside of mod_lock

 include/linux/codetag.h |  4 ++++
 include/linux/module.h  | 11 +++++++++++
 kernel/module/main.c    | 17 ++++++-----------
 lib/codetag.c           |  8 +++++---
 mm/alloc_tag.c          | 25 ++++++++++++++++++++++---
 5 files changed, 48 insertions(+), 17 deletions(-)

-- 
2.25.1