Re: [rcu:rcu/next 34/34] include/linux/rcupdate.h:426:6: error: 'rcu_scheduler_active' undeclared

[Paul E. McKenney]

On Wed, Nov 30, 2016 at 03:23:50AM +0800, kbuild test robot wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git rcu/next
> head:   ccc0666e2049e5818c236e647cf20c552a7b053b
> commit: ccc0666e2049e5818c236e647cf20c552a7b053b [34/34] rcu: Allow boot-time use of cond_resched_rcu_qs()
> config: i386-randconfig-x008-201648 (attached as .config)
> compiler: gcc-6 (Debian 6.2.0-3) 6.2.0 20160901
> reproduce:
>         git checkout ccc0666e2049e5818c236e647cf20c552a7b053b
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> All error/warnings (new ones prefixed by >>):

Fixed (albeit crudely) by 033a28bac0a20de78426e6faf3414637e4775fbc,
which replaces the offending commit.

							Thanx, Paul

>    In file included from include/linux/srcu.h:33:0,
>                     from include/linux/notifier.h:15,
>                     from include/linux/memory_hotplug.h:6,
>                     from include/linux/mmzone.h:777,
>                     from include/linux/gfp.h:5,
>                     from include/linux/mm.h:9,
>                     from mm/page_alloc.c:18:
>    mm/page_alloc.c: In function '__alloc_pages_nodemask':
> >> include/linux/rcupdate.h:426:6: error: 'rcu_scheduler_active' undeclared (first use in this function)
>      if (rcu_scheduler_active && !cond_resched()) \
>          ^
> >> mm/page_alloc.c:3746:2: note: in expansion of macro 'cond_resched_rcu_qs'
>      cond_resched_rcu_qs();
>      ^~~~~~~~~~~~~~~~~~~
>    include/linux/rcupdate.h:426:6: note: each undeclared identifier is reported only once for each function it appears in
>      if (rcu_scheduler_active && !cond_resched()) \
>          ^
> >> mm/page_alloc.c:3746:2: note: in expansion of macro 'cond_resched_rcu_qs'
>      cond_resched_rcu_qs();
>      ^~~~~~~~~~~~~~~~~~~
> --
>    In file included from include/linux/srcu.h:33:0,
>                     from include/linux/notifier.h:15,
>                     from include/linux/memory_hotplug.h:6,
>                     from include/linux/mmzone.h:777,
>                     from include/linux/gfp.h:5,
>                     from include/linux/mm.h:9,
>                     from mm/vmscan.c:16:
>    mm/vmscan.c: In function 'shrink_node_memcg':
> >> include/linux/rcupdate.h:426:6: error: 'rcu_scheduler_active' undeclared (first use in this function)
>      if (rcu_scheduler_active && !cond_resched()) \
>          ^
> >> mm/vmscan.c:2355:4: note: in expansion of macro 'cond_resched_rcu_qs'
>        cond_resched_rcu_qs();
>        ^~~~~~~~~~~~~~~~~~~
>    include/linux/rcupdate.h:426:6: note: each undeclared identifier is reported only once for each function it appears in
>      if (rcu_scheduler_active && !cond_resched()) \
>          ^
> >> mm/vmscan.c:2355:4: note: in expansion of macro 'cond_resched_rcu_qs'
>        cond_resched_rcu_qs();
>        ^~~~~~~~~~~~~~~~~~~
>    mm/vmscan.c: In function 'shrink_node':
> >> include/linux/rcupdate.h:426:6: error: 'rcu_scheduler_active' undeclared (first use in this function)
>      if (rcu_scheduler_active && !cond_resched()) \
>          ^
>    mm/vmscan.c:2535:6: note: in expansion of macro 'cond_resched_rcu_qs'
>          cond_resched_rcu_qs();
>          ^~~~~~~~~~~~~~~~~~~
> --
>    In file included from include/linux/srcu.h:33:0,
>                     from include/linux/notifier.h:15,
>                     from include/linux/memory_hotplug.h:6,
>                     from include/linux/mmzone.h:777,
>                     from include/linux/gfp.h:5,
>                     from include/linux/mm.h:9,
>                     from include/linux/mman.h:4,
>                     from mm/mlock.c:9:
>    mm/mlock.c: In function 'apply_mlockall_flags':
> >> include/linux/rcupdate.h:426:6: error: 'rcu_scheduler_active' undeclared (first use in this function)
>      if (rcu_scheduler_active && !cond_resched()) \
>          ^
>    mm/mlock.c:782:3: note: in expansion of macro 'cond_resched_rcu_qs'
>       cond_resched_rcu_qs();
>       ^~~~~~~~~~~~~~~~~~~
>    include/linux/rcupdate.h:426:6: note: each undeclared identifier is reported only once for each function it appears in
>      if (rcu_scheduler_active && !cond_resched()) \
>          ^
>    mm/mlock.c:782:3: note: in expansion of macro 'cond_resched_rcu_qs'
>       cond_resched_rcu_qs();
>       ^~~~~~~~~~~~~~~~~~~
> 
> vim +/rcu_scheduler_active +426 include/linux/rcupdate.h
> 
>    420	 * This macro resembles cond_resched(), except that it is defined to
>    421	 * report potential quiescent states to RCU-tasks even if the cond_resched()
>    422	 * machinery were to be shut off, as some advocate for PREEMPT kernels.
>    423	 */
>    424	#define cond_resched_rcu_qs() \
>    425	do { \
>  > 426		if (rcu_scheduler_active && !cond_resched()) \
>    427			rcu_note_voluntary_context_switch(current); \
>    428	} while (0)
>    429	
> 
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