Re: [PATCH v3 24/30] mm: memcontrol: prepare for reparenting LRU pages for lruvec lock

[Qi Zheng]

On 1/18/26 8:44 AM, Shakeel Butt wrote:
> On Fri, Jan 16, 2026 at 05:50:22PM +0800, Qi Zheng wrote:
> > On 1/16/26 5:43 PM, Muchun Song wrote:
> > > On 2026/1/14 19:32, Qi Zheng wrote:
> > > > From: Muchun Song <songmuchun@xxxxxxxxxxxxx>

[...]

> > > It seems that functions marked as `inline` cannot be decorated with
> > > `__acquires`? We’ve had to move these little helpers into `memcontrol.c`
> > > and declare them as extern, but they’re so short that it hardly feels
> >
> > Right, I received a compilation error reported LKP:
> >
> > All errors (new ones prefixed by >>):
> >
> >     In file included from crypto/ahash.c:26:
> >     In file included from include/net/netlink.h:6:
> >     In file included from include/linux/netlink.h:9:
> >     In file included from include/net/scm.h:9:
> >     In file included from include/linux/security.h:35:
> >     In file included from include/linux/bpf.h:32:
> > > > include/linux/memcontrol.h:772:14: error: use of undeclared identifier
> > 'lruvec'
> >       772 |         __acquires(&lruvec->lru_lock)
> >           |                     ^~~~~~
> >     include/linux/memcontrol.h:773:13: error: use of undeclared identifier
> > 'rcu'
> >       773 |         __acquires(rcu)
> >           |                    ^~~
> >     include/linux/memcontrol.h:775:14: error: use of undeclared identifier
> > 'lruvec'
> >       775 |         __acquires(&lruvec->lru_lock)
> >           |                     ^~~~~~
> >     include/linux/memcontrol.h:776:13: error: use of undeclared identifier
> > 'rcu'
> >       776 |         __acquires(rcu)
> >           |                    ^~~
> >     include/linux/memcontrol.h:779:14: error: use of undeclared identifier
> > 'lruvec'
> >       779 |         __acquires(&lruvec->lru_lock)
> >           |                     ^~~~~~
> >     include/linux/memcontrol.h:780:13: error: use of undeclared identifier
> > 'rcu'
> >       780 |         __acquires(rcu)
> >           |                    ^~~
> >     include/linux/memcontrol.h:1507:13: error: use of undeclared identifier
> > 'rcu'
> >      1507 |         __acquires(rcu)
> >           |                    ^~~
> >     include/linux/memcontrol.h:1515:13: error: use of undeclared identifier
> > 'rcu'
> >      1515 |         __releases(rcu)
> >           |                    ^~~
> >     include/linux/memcontrol.h:1523:13: error: use of undeclared identifier
> > 'rcu'
> >      1523 |         __releases(rcu)
> >           |                    ^~~
> >     include/linux/memcontrol.h:1532:13: error: use of undeclared identifier
> > 'rcu'
> >      1532 |         __releases(rcu)
> >
> > And I reproduced this error with the following configuration:
> >
> > 1. enable CONFIG_WARN_CONTEXT_ANALYSIS_ALL
> > 2. make CC=clang bzImage (clang version >= 22)
> >
> > > worth the trouble. My own inclination is to drop the `__acquires`
> > > annotations—mainly for performance reasons.
> >
> > If no one else objects, I will drop __acquires/__releases in the next
> > version.
>
> If you drop these annotations from header file and keep in the C file,
> do you still get the compilation error?

I did test it this way, and it does fix the compilation error, but
Muchun thinks these functions are very simple and there's no need to put
them in a C file.

>