Re: nfs compile error nfslocalio.o and localio.o since v6.14-rc1

["Pali Rohár" <pali@kernel.org>]

On Saturday 15 February 2025 11:41:25 Chuck Lever wrote:
> On 2/15/25 11:38 AM, Pali Rohár wrote:
> > On Saturday 15 February 2025 11:29:45 Chuck Lever wrote:
> >> Hi Pali -
> >>
> >> On 2/15/25 7:00 AM, Pali Rohár wrote:
> >>> Hello, since v6.14-rc1, file nfslocalio.c cannot be compiled with
> >>> gcc-8.3 and attached .config file. Same problem is with localio.c.
> >>
> >> If the interwebs are correct, gcc-8.3 was released in 2014. ISTR that
> >> recent releases of the Linux kernel no longer support gcc versions that
> >> old.
> > 
> > Hello, I know that this is old version, and I specially used it just to
> > check if everything compiles correctly. And it failed.
> > 
> > Per https://docs.kernel.org/process/changes.html the minimal version of
> > gcc is 5.1, so I think that compilation with gcc 8.3 should still be
> > supported.
> > 
> >> It appears to be snagging on kernel-wide utility helpers, not code
> >> specific to NFS.
> > 
> > It looks like that, but only those two nfs files cause compile errors.
> > Everything else compiles without problem. So it is quite suspicious and
> > maybe it could signal that those helper are used incorrectly in nfs
> > code? I'm not sure, I have not investigated it.
> 
> A bisect would be helpful.
> 
> Also, what is the CPU platform architecture? x86_64?

Yes, it is x86_64, I hope that all details/configuration is in the
.config file. I took generic gcc 8.3 version which was distributed by
some debian version. So nothing special.

> 
> >> If that's the case, it might not be possible for us to address this
> >> breakage.
> >>
> >> Adding Mike, who contributed this code.
> >>
> >>> Error is:
> >>>
> >>> $ make bzImage
> >>>   CALL    scripts/checksyscalls.sh
> >>>   DESCEND objtool
> >>>   INSTALL libsubcmd_headers
> >>>   CC      fs/nfs_common/nfslocalio.o
> >>> In file included from ./include/linux/rbtree.h:24,
> >>>                  from ./include/linux/mm_types.h:11,
> >>>                  from ./include/linux/mmzone.h:22,
> >>>                  from ./include/linux/gfp.h:7,
> >>>                  from ./include/linux/umh.h:4,
> >>>                  from ./include/linux/kmod.h:9,
> >>>                  from ./include/linux/module.h:17,
> >>>                  from fs/nfs_common/nfslocalio.c:7:
> >>> fs/nfs_common/nfslocalio.c: In function ‘nfs_close_local_fh’:
> >>> ./include/linux/rcupdate.h:531:9: error: dereferencing pointer to incomplete type ‘struct nfsd_file’
> >>>   typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
> >>>          ^
> >>> ./include/linux/rcupdate.h:650:31: note: in expansion of macro ‘__rcu_access_pointer’
> >>>  #define rcu_access_pointer(p) __rcu_access_pointer((p), __UNIQUE_ID(rcu), __rcu)
> >>>                                ^~~~~~~~~~~~~~~~~~~~
> >>> fs/nfs_common/nfslocalio.c:288:10: note: in expansion of macro ‘rcu_access_pointer’
> >>>   ro_nf = rcu_access_pointer(nfl->ro_file);
> >>>           ^~~~~~~~~~~~~~~~~~
> >>> make[4]: *** [scripts/Makefile.build:207: fs/nfs_common/nfslocalio.o] Error 1
> >>> make[3]: *** [scripts/Makefile.build:465: fs/nfs_common] Error 2
> >>> make[2]: *** [scripts/Makefile.build:465: fs] Error 2
> >>> make[1]: *** [/home/pali/develop/kernel.org/linux/Makefile:1994: .] Error 2
> >>> make: *** [Makefile:251: __sub-make] Error 2
> >>>
> >>>
> >>> $ make fs/nfs/localio.o
> >>>   CALL    scripts/checksyscalls.sh
> >>>   DESCEND objtool
> >>>   INSTALL libsubcmd_headers
> >>>   CC      fs/nfs/localio.o
> >>> In file included from ./include/linux/rbtree.h:24,
> >>>                  from ./include/linux/mm_types.h:11,
> >>>                  from ./include/linux/mmzone.h:22,
> >>>                  from ./include/linux/gfp.h:7,
> >>>                  from ./include/linux/umh.h:4,
> >>>                  from ./include/linux/kmod.h:9,
> >>>                  from ./include/linux/module.h:17,
> >>>                  from fs/nfs/localio.c:11:
> >>> fs/nfs/localio.c: In function ‘nfs_local_open_fh’:
> >>> ./include/linux/rcupdate.h:538:9: error: dereferencing pointer to incomplete type ‘struct nfsd_file’
> >>>   typeof(*p) *local = (typeof(*p) *__force)READ_ONCE(p); \
> >>>          ^
> >>> ./include/linux/rcupdate.h:686:2: note: in expansion of macro ‘__rcu_dereference_check’
> >>>   __rcu_dereference_check((p), __UNIQUE_ID(rcu), \
> >>>   ^~~~~~~~~~~~~~~~~~~~~~~
> >>> ./include/linux/rcupdate.h:758:28: note: in expansion of macro ‘rcu_dereference_check’
> >>>  #define rcu_dereference(p) rcu_dereference_check(p, 0)
> >>>                             ^~~~~~~~~~~~~~~~~~~~~
> >>> fs/nfs/localio.c:275:7: note: in expansion of macro ‘rcu_dereference’
> >>>   nf = rcu_dereference(*pnf);
> >>>        ^~~~~~~~~~~~~~~
> >>> make[4]: *** [scripts/Makefile.build:207: fs/nfs/localio.o] Error 1
> >>> make[3]: *** [scripts/Makefile.build:465: fs/nfs] Error 2
> >>> make[2]: *** [scripts/Makefile.build:465: fs] Error 2
> >>> make[1]: *** [/home/pali/develop/kernel.org/linux/Makefile:1994: .] Error 2
> >>> make: *** [Makefile:251: __sub-make] Error 2
> >>>
> >>>
> >>> Reproduced from commit 7ff71e6d9239 ("Merge tag 'alpha-fixes-v6.14-rc2'
> >>> of git://git.kernel.org/pub/scm/linux/kernel/git/mattst88/alpha").
> >>
> >>
> >> -- 
> >> Chuck Lever
> 
> 
> -- 
> Chuck Lever