| Message ID | 20160623023756.GA30438@js1304-P5Q-DELUXE (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, Jun 23, 2016 at 11:37:56AM +0900, Joonsoo Kim wrote: > On Wed, Jun 22, 2016 at 05:49:35PM -0700, Paul E. McKenney wrote: > > On Wed, Jun 22, 2016 at 12:08:59PM -0700, Paul E. McKenney wrote: > > > On Wed, Jun 22, 2016 at 05:01:35PM +0200, Geert Uytterhoeven wrote: > > > > On Wed, Jun 22, 2016 at 2:52 AM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote: > > > > > Could you try below patch to check who causes the hang? > > > > > > > > > > And, if sysalt-t works when hang, could you get sysalt-t output? I haven't > > > > > used it before but Paul could find some culprit on it. :) > > > > > > > > > > Thanks. > > > > > > > > > > > > > > > ----->8----- > > > > > diff --git a/mm/slab.c b/mm/slab.c > > > > > index 763096a..9652d38 100644 > > > > > --- a/mm/slab.c > > > > > +++ b/mm/slab.c > > > > > @@ -964,8 +964,13 @@ static int setup_kmem_cache_node(struct kmem_cache *cachep, > > > > > * guaranteed to be valid until irq is re-enabled, because it will be > > > > > * freed after synchronize_sched(). > > > > > */ > > > > > - if (force_change) > > > > > + if (force_change) { > > > > > + if (num_online_cpus() > 1) > > > > > + dump_stack(); > > > > > synchronize_sched(); > > > > > + if (num_online_cpus() > 1) > > > > > + dump_stack(); > > > > > + } > > > > > > > > I've only added the first one, as I would never see the second one. All of > > > > this happens before the serial console is activated, earlycon is not supported, > > > > and I only have remote access. > > > > > > > > Brought up 2 CPUs > > > > SMP: Total of 2 processors activated (2132.00 BogoMIPS). > > > > CPU: All CPU(s) started in SVC mode. > > > > CPU: 0 PID: 1 Comm: swapper/0 Not tainted > > > > 4.7.0-rc4-kzm9d-00404-g4a235e6dde4404dd-dirty #89 > > > > Hardware name: Generic Emma Mobile EV2 (Flattened Device Tree) > > > > [<c010de68>] (unwind_backtrace) from [<c010a658>] (show_stack+0x10/0x14) > > > > [<c010a658>] (show_stack) from [<c02b5cf8>] (dump_stack+0x7c/0x9c) > > > > [<c02b5cf8>] (dump_stack) from [<c01cfa4c>] (setup_kmem_cache_node+0x140/0x170) > > > > [<c01cfa4c>] (setup_kmem_cache_node) from [<c01cfe3c>] > > > > (__do_tune_cpucache+0xf4/0x114) > > > > [<c01cfe3c>] (__do_tune_cpucache) from [<c01cff54>] (enable_cpucache+0xf8/0x148) > > > > [<c01cff54>] (enable_cpucache) from [<c01d0190>] > > > > (__kmem_cache_create+0x1a8/0x1d0) > > > > [<c01d0190>] (__kmem_cache_create) from [<c01b32d0>] > > > > (kmem_cache_create+0xbc/0x190) > > > > [<c01b32d0>] (kmem_cache_create) from [<c070d968>] (shmem_init+0x34/0xb0) > > > > [<c070d968>] (shmem_init) from [<c0700cc8>] (kernel_init_freeable+0x98/0x1ec) > > > > [<c0700cc8>] (kernel_init_freeable) from [<c049fdbc>] (kernel_init+0x8/0x110) > > > > [<c049fdbc>] (kernel_init) from [<c0106cb8>] (ret_from_fork+0x14/0x3c) > > > > devtmpfs: initialized > > > > > > I don't see anything here that would prevent grace periods from completing. > > > > > > The CPUs are using the normal hotplug sequence to come online, correct? > > > > And either way, could you please apply the patch below and then > > invoke rcu_dump_rcu_sched_tree() just before the offending call to > > synchronize_sched()? That will tell me what CPUs RCU believes exist, > > and perhaps also which CPU is holding it up. > > I can't find rcu_dump_rcu_sched_tree(). Do you mean > rcu_dump_rcu_node_tree()? Anyway, there is no patch below so I attach > one which does what Paul want, maybe. One of those days, I guess! :-/ Your patch is exactly what I intended to send, thank you! Thanx, Paul > Thanks. > > ------->8--------- > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 88d3f95..6b650f0 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -4171,7 +4171,7 @@ static void __init rcu_init_geometry(void) > * Dump out the structure of the rcu_node combining tree associated > * with the rcu_state structure referenced by rsp. > */ > -static void __init rcu_dump_rcu_node_tree(struct rcu_state *rsp) > +static void rcu_dump_rcu_node_tree(struct rcu_state *rsp) > { > int level = 0; > struct rcu_node *rnp; > @@ -4189,6 +4189,11 @@ static void __init rcu_dump_rcu_node_tree(struct rcu_state *rsp) > pr_cont("\n"); > } > > +void rcu_dump_rcu_sched_tree(void) > +{ > + rcu_dump_rcu_node_tree(&rcu_sched_state); > +} > + > void __init rcu_init(void) > { > int cpu; > diff --git a/mm/slab.c b/mm/slab.c > index 763096a..d88976c 100644 > --- a/mm/slab.c > +++ b/mm/slab.c > @@ -909,6 +909,8 @@ static int init_cache_node_node(int node) > return 0; > } > > +extern void rcu_dump_rcu_sched_tree(void); > + > static int setup_kmem_cache_node(struct kmem_cache *cachep, > int node, gfp_t gfp, bool force_change) > { > @@ -964,8 +966,10 @@ static int setup_kmem_cache_node(struct kmem_cache *cachep, > * guaranteed to be valid until irq is re-enabled, because it will be > * freed after synchronize_sched(). > */ > - if (force_change) > + if (force_change) { > + rcu_dump_rcu_sched_tree(); > synchronize_sched(); > + } > > fail: > kfree(old_shared); >
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 88d3f95..6b650f0 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4171,7 +4171,7 @@ static void __init rcu_init_geometry(void) * Dump out the structure of the rcu_node combining tree associated * with the rcu_state structure referenced by rsp. */ -static void __init rcu_dump_rcu_node_tree(struct rcu_state *rsp) +static void rcu_dump_rcu_node_tree(struct rcu_state *rsp) { int level = 0; struct rcu_node *rnp; @@ -4189,6 +4189,11 @@ static void __init rcu_dump_rcu_node_tree(struct rcu_state *rsp) pr_cont("\n"); } +void rcu_dump_rcu_sched_tree(void) +{ + rcu_dump_rcu_node_tree(&rcu_sched_state); +} + void __init rcu_init(void) { int cpu; diff --git a/mm/slab.c b/mm/slab.c index 763096a..d88976c 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -909,6 +909,8 @@ static int init_cache_node_node(int node) return 0; } +extern void rcu_dump_rcu_sched_tree(void); + static int setup_kmem_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp, bool force_change) { @@ -964,8 +966,10 @@ static int setup_kmem_cache_node(struct kmem_cache *cachep, * guaranteed to be valid until irq is re-enabled, because it will be * freed after synchronize_sched(). */ - if (force_change) + if (force_change) { + rcu_dump_rcu_sched_tree(); synchronize_sched(); + } fail: kfree(old_shared);