Messages in this thread | | | Subject | Re: next: Commit 'mm: Prevent __alloc_pages_nodemask() RCU CPU stall ...' causing hang on sparc32 qemu | From | Guenter Roeck <> | Date | Wed, 30 Nov 2016 02:52:11 -0800 |
| |
On 11/29/2016 11:02 PM, Paul E. McKenney wrote: > On Tue, Nov 29, 2016 at 08:32:51PM -0800, Guenter Roeck wrote: >> On 11/29/2016 05:28 PM, Paul E. McKenney wrote: >>> On Tue, Nov 29, 2016 at 01:23:08PM -0800, Guenter Roeck wrote: >>>> Hi Paul, >>>> >>>> most of my qemu tests for sparc32 targets started to fail in next-20161129. >>>> The problem is only seen in SMP builds; non-SMP builds are fine. >>>> Bisect points to commit 2d66cccd73436 ("mm: Prevent __alloc_pages_nodemask() >>>> RCU CPU stall warnings"); reverting that commit fixes the problem. >>>> >>>> Test scripts are available at: >>>> https://github.com/groeck/linux-build-test/tree/master/rootfs/sparc >>>> Test results are at: >>>> https://github.com/groeck/linux-build-test/tree/master/rootfs/sparc >>>> >>>> Bisect log is attached. >>>> >>>> Please let me know if there is anything I can do to help tracking down the >>>> problem. >>> >>> Apologies!!! Does the patch below help? >>> >> No, sorry, it doesn't make a difference. > > Interesting... Could you please send me the build failure messages? >
There is no failure message; it just hangs until I abort the qemu session.
http://kerneltests.org/builders/qemu-sparc-next/builds/532/steps/qemubuildcommand/logs/stdio
Guenter
> Thanx, Paul > >> Guenter >> >>> Thanx, Paul >>> >>> ------------------------------------------------------------------------ >>> >>> commit 97708e737e2a55fed4bdbc005bf05ea909df6b73 >>> Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com> >>> Date: Tue Nov 29 11:06:05 2016 -0800 >>> >>> rcu: Allow boot-time use of cond_resched_rcu_qs() >>> >>> The cond_resched_rcu_qs() macro is used to force RCU quiescent states into >>> long-running in-kernel loops. However, some of these loops can execute >>> during early boot when interrupts are disabled, and during which time >>> it is therefore illegal to enter the scheduler. This commit therefore >>> makes cond_resched_rcu_qs() be a no-op during early boot. >>> >>> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> >>> >>> diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h >>> index 525ca34603b7..b6944cc19a07 100644 >>> --- a/include/linux/rcupdate.h >>> +++ b/include/linux/rcupdate.h >>> @@ -423,7 +423,7 @@ extern struct srcu_struct tasks_rcu_exit_srcu; >>> */ >>> #define cond_resched_rcu_qs() \ >>> do { \ >>> - if (!cond_resched()) \ >>> + if (!is_idle_task(current) && !cond_resched()) \ >>> rcu_note_voluntary_context_switch(current); \ >>> } while (0) >>> >>> diff --git a/include/linux/rcutiny.h b/include/linux/rcutiny.h >>> index 7232d199a81c..20f5990deeee 100644 >>> --- a/include/linux/rcutiny.h >>> +++ b/include/linux/rcutiny.h >>> @@ -228,6 +228,7 @@ static inline void exit_rcu(void) >>> extern int rcu_scheduler_active __read_mostly; >>> void rcu_scheduler_starting(void); >>> #else /* #ifdef CONFIG_DEBUG_LOCK_ALLOC */ >>> +#define rcu_scheduler_active false >>> static inline void rcu_scheduler_starting(void) >>> { >>> } >>> >>> >> > >
| |