Re: [PATCH v2 1/7] memcg: memcg_rstat_updated re-entrant safe against irqs

[Lorenzo Stoakes <lorenzo.stoakes@oracle.com>]

On Thu, May 15, 2025 at 07:31:09AM -0700, Shakeel Butt wrote:
> On Thu, May 15, 2025 at 5:47 AM Lorenzo Stoakes
> <lorenzo.stoakes@oracle.com> wrote:
> >
> > Shakeel - This breaks the build in mm-new for me:
> >
> >   CC      mm/pt_reclaim.o
> > In file included from ./arch/x86/include/asm/rmwcc.h:5,
> >                  from ./arch/x86/include/asm/bitops.h:18,
> >                  from ./include/linux/bitops.h:68,
> >                  from ./include/linux/radix-tree.h:11,
> >                  from ./include/linux/idr.h:15,
> >                  from ./include/linux/cgroup-defs.h:13,
> >                  from mm/memcontrol.c:28:
> > mm/memcontrol.c: In function ‘mem_cgroup_alloc’:
> > ./arch/x86/include/asm/percpu.h:39:45: error: expected identifier or ‘(’ before ‘__seg_gs’
> >    39 | #define __percpu_seg_override   CONCATENATE(__seg_, __percpu_seg)
> >       |                                             ^~~~~~
> > ./include/linux/args.h:25:24: note: in definition of macro ‘__CONCAT’
> >    25 | #define __CONCAT(a, b) a ## b
> >       |                        ^
> > ./arch/x86/include/asm/percpu.h:39:33: note: in expansion of macro ‘CONCATENATE’
> >    39 | #define __percpu_seg_override   CONCATENATE(__seg_, __percpu_seg)
> >       |                                 ^~~~~~~~~~~
> > ./arch/x86/include/asm/percpu.h:93:33: note: in expansion of macro ‘__percpu_seg_override’
> >    93 | # define __percpu_qual          __percpu_seg_override
> >       |                                 ^~~~~~~~~~~~~~~~~~~~~
> > ././include/linux/compiler_types.h:60:25: note: in expansion of macro ‘__percpu_qual’
> >    60 | # define __percpu       __percpu_qual BTF_TYPE_TAG(percpu)
> >       |                         ^~~~~~~~~~~~~
> > mm/memcontrol.c:3700:45: note: in expansion of macro ‘__percpu’
> >  3700 |         struct memcg_vmstats_percpu *statc, __percpu *pstatc_pcpu;
> >       |                                             ^~~~~~~~
> > mm/memcontrol.c:3731:25: error: ‘pstatc_pcpu’ undeclared (first use in this function); did you mean ‘kstat_cpu’?
> >  3731 |                         pstatc_pcpu = parent->vmstats_percpu;
> >       |                         ^~~~~~~~~~~
> >       |                         kstat_cpu
> > mm/memcontrol.c:3731:25: note: each undeclared identifier is reported only once for each function it appears in
> >
> > The __percpu macro seems to be a bit screwy with comma-delimited decls, as it
> > seems that putting this on its own line fixes this problem:
> >
>
> Which compiler (and version) is this? Thanks for the fix.

gcc 15, but apparently 13, 14 also fail. It seems independent of config.