On Mon, Sep 07, 2026 at 04:13:26PM +0800, Ye Liu wrote:
> From: Ye Liu <liuye@kylinos.cn>
>
> Introduce for_each_process_rculock(), for_each_thread_rculock() and
> for_each_process_thread_rculock() macros that combine the existing
> iteration macros with scoped_guard(rcu), so that the RCU read lock
> is automatically acquired before iteration and released when the
> loop exits — including via break, goto, or return.
>
> The rest of the series converts manual rcu_read_lock()/
> rcu_read_unlock() and guard(rcu)() pairs across mm/, kernel/, fs/,
> lib/ and security/ to use the new macros.
>
Andrew - just a note (assuming Ye Liu is in agreement) I think all of the
below should be excluded from the cover letter that goes into the commit
message, including the checkpatch thing.
> Changes since v1 [1]:
> - Rename macros from *_rcu to *_rculock, as suggested by Steven
> Rostedt and acked by Thomas Gleixner, to avoid confusion with
> existing *_rcu() list iterators that expect the caller to hold
> the RCU read lock.
> - Improve the comment on for_each_process_thread_rculock() to
> document that 'break' only exits the inner loop and 'goto' is
> needed to exit both loops (Thomas Gleixner).
> - Rename the stale 'unlock:' label to 'out:' in hung_task.c, as
> noted by Günther Noack.
> - Clarify in patch 4 that page_pgoff() is safe outside the RCU
> read-side critical section (SJ Park).
> - CC all relevant maintainers on every patch (Lorenzo Stoakes).
> - Drop the mm: prefix from patch 1, as the macros are in
> include/linux/sched/signal.h (Michal Hocko).
>
> Patch 1 may trigger checkpatch "Macros with complex values should be
> enclosed in parentheses" errors. These are false positives — the
> scoped_guard() pattern is a control-flow construct, not a multi-
> statement macro, and the same idiom is used elsewhere in the kernel.
While it's useful as a note to reviewers, in general checkpatch is taken
with a pinch of salt - it's a master of false positives so usually no need
to say this :)
>
> Suggested by Michal Hocko for the oom_kill path [2].
>
> [1] https://lore.kernel.org/all/20260904083001.553587-1-ye.liu@linux.dev/
> [2] https://lore.kernel.org/all/20260813092933.562028-1-ye.liu@linux.dev/
>
> Ye Liu (8):
> sched: introduce for_each_process_rculock and for_each_thread_rculock
> mm/oom_kill: convert process/thread iterators to for_each_*_rculock
> mm/ksm: convert process iterator to for_each_process_rculock
> mm/memory-failure: convert process iterator to for_each_process_rculock
> kernel: convert process/thread iterators to for_each_*_rculock
> fs: convert process/thread iterators to for_each_*_rculock
> lib: convert process iterator to for_each_process_rculock
> security/landlock: convert thread iterator to for_each_thread_rculock
>
> fs/proc/base.c | 4 +---
> fs/resctrl/rdtgroup.c | 8 ++------
> include/linux/sched/signal.h | 25 +++++++++++++++++++++++++
> kernel/cpu.c | 4 +---
> kernel/freezer.c | 4 +---
> kernel/hung_task.c | 11 ++++-------
> kernel/locking/lockdep.c | 4 +---
> kernel/rcu/update.c | 4 +---
> kernel/sched/core.c | 3 +--
> kernel/sched/debug.c | 4 +---
> kernel/trace/fgraph.c | 8 ++------
> kernel/unwind/deferred.c | 3 +--
> lib/is_single_threaded.c | 5 +----
> mm/ksm.c | 4 +---
> mm/memory-failure.c | 16 ++++------------
> mm/oom_kill.c | 20 +++++---------------
> security/landlock/tsync.c | 8 ++------
> 17 files changed, 54 insertions(+), 81 deletions(-)
>
> Signed-off-by: Ye Liu <liuye@kylinos.cn>
>
> --
> 2.25.1
--
Cheers, Lorenzo