* [PATCH 0/2] srcu: Fix early boot hang v3
@ 2021-04-14 13:24 Frederic Weisbecker
2021-04-14 13:24 ` [PATCH 1/2] srcu: Fix broken node geometry after early ssp init Frederic Weisbecker
2021-04-14 13:24 ` [PATCH 2/2] srcu: Early test SRCU polling start Frederic Weisbecker
0 siblings, 2 replies; 10+ messages in thread
From: Frederic Weisbecker @ 2021-04-14 13:24 UTC (permalink / raw)
To: Paul E . McKenney
Cc: LKML, Frederic Weisbecker, Uladzislau Rezki, Boqun Feng,
Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes
Hi,
Another approach, suggested offlist by Paul. Much more
simple and maintainable. Enjoy!
git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks.git
rcu/dev-v3
HEAD: bd6cef5d990e47a523027aea95f80537644af55e
Thanks,
Frederic
---
Frederic Weisbecker (2):
srcu: Fix broken node geometry after early ssp init
srcu: Early test SRCU polling start
kernel/rcu/rcu.h | 3 +++
kernel/rcu/srcutree.c | 2 ++
kernel/rcu/tree.c | 18 +++++++++++++++++-
kernel/rcu/update.c | 6 +++++-
4 files changed, 27 insertions(+), 2 deletions(-)
^ permalink raw reply [flat|nested] 10+ messages in thread* [PATCH 1/2] srcu: Fix broken node geometry after early ssp init 2021-04-14 13:24 [PATCH 0/2] srcu: Fix early boot hang v3 Frederic Weisbecker @ 2021-04-14 13:24 ` Frederic Weisbecker 2021-04-14 15:55 ` Paul E. McKenney 2021-04-14 13:24 ` [PATCH 2/2] srcu: Early test SRCU polling start Frederic Weisbecker 1 sibling, 1 reply; 10+ messages in thread From: Frederic Weisbecker @ 2021-04-14 13:24 UTC (permalink / raw) To: Paul E . McKenney Cc: LKML, Frederic Weisbecker, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes An ssp initialized before rcu_init_geometry() will have its snp hierarchy based on CONFIG_NR_CPUS. Once rcu_init_geometry() is called, the nodes distribution is shrinked and optimized toward meeting the actual possible number of CPUs detected on boot. Later on, the ssp that was initialized before rcu_init_geometry() is confused and sometimes refers to its initial CONFIG_NR_CPUS based node hierarchy, sometimes to the new num_possible_cpus() based one instead. For example each of its sdp->mynode remain backward and refer to the early node leaves that may not exist anymore. On the other hand the srcu_for_each_node_breadth_first() refers to the new node hierarchy. There are at least two bad possible outcomes to this: 1) a) A callback enqueued early on an sdp is recorded pending on sdp->mynode->srcu_data_have_cbs in srcu_funnel_gp_start() with sdp->mynode pointing to a deep leaf (say 3 levels). b) The grace period ends after rcu_init_geometry() which shrinks the nodes level to a single one. srcu_gp_end() walks through the new snp hierarchy without ever reaching the old leaves so the callback is never executed. This is easily reproduced on an 8 CPUs machine with CONFIG_NR_CPUS >= 32 and "rcupdate.rcu_self_test=1". The srcu_barrier() after early tests verification never completes and the boot hangs: [ 5413.141029] INFO: task swapper/0:1 blocked for more than 4915 seconds. [ 5413.147564] Not tainted 5.12.0-rc4+ #28 [ 5413.151927] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5413.159753] task:swapper/0 state:D stack: 0 pid: 1 ppid: 0 flags:0x00004000 [ 5413.168099] Call Trace: [ 5413.170555] __schedule+0x36c/0x930 [ 5413.174057] ? wait_for_completion+0x88/0x110 [ 5413.178423] schedule+0x46/0xf0 [ 5413.181575] schedule_timeout+0x284/0x380 [ 5413.185591] ? wait_for_completion+0x88/0x110 [ 5413.189957] ? mark_held_locks+0x61/0x80 [ 5413.193882] ? mark_held_locks+0x61/0x80 [ 5413.197809] ? _raw_spin_unlock_irq+0x24/0x50 [ 5413.202173] ? wait_for_completion+0x88/0x110 [ 5413.206535] wait_for_completion+0xb4/0x110 [ 5413.210724] ? srcu_torture_stats_print+0x110/0x110 [ 5413.215610] srcu_barrier+0x187/0x200 [ 5413.219277] ? rcu_tasks_verify_self_tests+0x50/0x50 [ 5413.224244] ? rdinit_setup+0x2b/0x2b [ 5413.227907] rcu_verify_early_boot_tests+0x2d/0x40 [ 5413.232700] do_one_initcall+0x63/0x310 [ 5413.236541] ? rdinit_setup+0x2b/0x2b [ 5413.240207] ? rcu_read_lock_sched_held+0x52/0x80 [ 5413.244912] kernel_init_freeable+0x253/0x28f [ 5413.249273] ? rest_init+0x250/0x250 [ 5413.252846] kernel_init+0xa/0x110 [ 5413.256257] ret_from_fork+0x22/0x30 2) An ssp that gets initialized before rcu_init_geometry() and used afterward will always have stale rdp->mynode references, resulting in callbacks to be missed in srcu_gp_end(), just like in the previous scenario. Solve this with calling rcu_init_geometry() whenever an struct srcu_state happens to be initialized before rcu_init(). This way we make sure the RCU nodes hierarchy is properly built and distributed before the nodes of a struct srcu_state are allocated. Suggested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Uladzislau Rezki <urezki@gmail.com> --- kernel/rcu/rcu.h | 3 +++ kernel/rcu/srcutree.c | 2 ++ kernel/rcu/tree.c | 18 +++++++++++++++++- 3 files changed, 22 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 75ed367d5b60..24db97cbf76b 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -278,6 +278,7 @@ extern void resched_cpu(int cpu); extern int rcu_num_lvls; extern int num_rcu_lvl[]; extern int rcu_num_nodes; +extern bool rcu_geometry_initialized; static bool rcu_fanout_exact; static int rcu_fanout_leaf; @@ -308,6 +309,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) } } +extern void rcu_init_geometry(void); + /* Returns a pointer to the first leaf rcu_node structure. */ #define rcu_first_leaf_node() (rcu_state.level[rcu_num_lvls - 1]) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 108f9ca06047..05ca3c275af1 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -171,6 +171,8 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) ssp->sda = alloc_percpu(struct srcu_data); if (!ssp->sda) return -ENOMEM; + if (!rcu_geometry_initialized) + rcu_init_geometry(); init_srcu_struct_nodes(ssp); ssp->srcu_gp_seq_needed_exp = 0; ssp->srcu_last_gp_end = ktime_get_mono_fast_ns(); diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 740f5cd34459..b1d6e60e08d1 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4556,17 +4556,33 @@ static void __init rcu_init_one(void) } } +bool rcu_geometry_initialized __read_mostly; + /* * Compute the rcu_node tree geometry from kernel parameters. This cannot * replace the definitions in tree.h because those are needed to size * the ->node array in the rcu_state structure. */ -static void __init rcu_init_geometry(void) +void rcu_init_geometry(void) { ulong d; int i; + static unsigned long old_nr_cpu_ids; int rcu_capacity[RCU_NUM_LVLS]; + if (rcu_geometry_initialized) { + /* + * Arrange for warning if rcu_init_geometry() was called before + * setup_nr_cpu_ids(). We may miss cases when + * nr_cpus_ids == NR_CPUS but that shouldn't matter too much. + */ + WARN_ON_ONCE(old_nr_cpu_ids != nr_cpu_ids); + return; + } + + old_nr_cpu_ids = nr_cpu_ids; + rcu_geometry_initialized = true; + /* * Initialize any unspecified boot parameters. * The default values of jiffies_till_first_fqs and -- 2.25.1 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] srcu: Fix broken node geometry after early ssp init 2021-04-14 13:24 ` [PATCH 1/2] srcu: Fix broken node geometry after early ssp init Frederic Weisbecker @ 2021-04-14 15:55 ` Paul E. McKenney 2021-04-16 23:38 ` Frederic Weisbecker 2021-04-17 13:16 ` Frederic Weisbecker 0 siblings, 2 replies; 10+ messages in thread From: Paul E. McKenney @ 2021-04-14 15:55 UTC (permalink / raw) To: Frederic Weisbecker Cc: LKML, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes On Wed, Apr 14, 2021 at 03:24:12PM +0200, Frederic Weisbecker wrote: > An ssp initialized before rcu_init_geometry() will have its snp hierarchy > based on CONFIG_NR_CPUS. > > Once rcu_init_geometry() is called, the nodes distribution is shrinked > and optimized toward meeting the actual possible number of CPUs detected > on boot. > > Later on, the ssp that was initialized before rcu_init_geometry() is > confused and sometimes refers to its initial CONFIG_NR_CPUS based node > hierarchy, sometimes to the new num_possible_cpus() based one instead. > For example each of its sdp->mynode remain backward and refer to the > early node leaves that may not exist anymore. On the other hand the > srcu_for_each_node_breadth_first() refers to the new node hierarchy. > > There are at least two bad possible outcomes to this: > > 1) a) A callback enqueued early on an sdp is recorded pending on > sdp->mynode->srcu_data_have_cbs in srcu_funnel_gp_start() with > sdp->mynode pointing to a deep leaf (say 3 levels). > > b) The grace period ends after rcu_init_geometry() which shrinks the > nodes level to a single one. srcu_gp_end() walks through the new > snp hierarchy without ever reaching the old leaves so the callback > is never executed. > > This is easily reproduced on an 8 CPUs machine with > CONFIG_NR_CPUS >= 32 and "rcupdate.rcu_self_test=1". The > srcu_barrier() after early tests verification never completes and > the boot hangs: > > [ 5413.141029] INFO: task swapper/0:1 blocked for more than 4915 seconds. > [ 5413.147564] Not tainted 5.12.0-rc4+ #28 > [ 5413.151927] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 5413.159753] task:swapper/0 state:D stack: 0 pid: 1 ppid: 0 flags:0x00004000 > [ 5413.168099] Call Trace: > [ 5413.170555] __schedule+0x36c/0x930 > [ 5413.174057] ? wait_for_completion+0x88/0x110 > [ 5413.178423] schedule+0x46/0xf0 > [ 5413.181575] schedule_timeout+0x284/0x380 > [ 5413.185591] ? wait_for_completion+0x88/0x110 > [ 5413.189957] ? mark_held_locks+0x61/0x80 > [ 5413.193882] ? mark_held_locks+0x61/0x80 > [ 5413.197809] ? _raw_spin_unlock_irq+0x24/0x50 > [ 5413.202173] ? wait_for_completion+0x88/0x110 > [ 5413.206535] wait_for_completion+0xb4/0x110 > [ 5413.210724] ? srcu_torture_stats_print+0x110/0x110 > [ 5413.215610] srcu_barrier+0x187/0x200 > [ 5413.219277] ? rcu_tasks_verify_self_tests+0x50/0x50 > [ 5413.224244] ? rdinit_setup+0x2b/0x2b > [ 5413.227907] rcu_verify_early_boot_tests+0x2d/0x40 > [ 5413.232700] do_one_initcall+0x63/0x310 > [ 5413.236541] ? rdinit_setup+0x2b/0x2b > [ 5413.240207] ? rcu_read_lock_sched_held+0x52/0x80 > [ 5413.244912] kernel_init_freeable+0x253/0x28f > [ 5413.249273] ? rest_init+0x250/0x250 > [ 5413.252846] kernel_init+0xa/0x110 > [ 5413.256257] ret_from_fork+0x22/0x30 > > 2) An ssp that gets initialized before rcu_init_geometry() and used > afterward will always have stale rdp->mynode references, resulting in > callbacks to be missed in srcu_gp_end(), just like in the previous > scenario. > > Solve this with calling rcu_init_geometry() whenever an struct srcu_state > happens to be initialized before rcu_init(). This way we make sure the > RCU nodes hierarchy is properly built and distributed before the nodes > of a struct srcu_state are allocated. > > Suggested-by: Paul E. McKenney <paulmck@kernel.org> > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Much much nicer, thank you! Comments and questions interspersed. Thanx, Paul > Cc: Boqun Feng <boqun.feng@gmail.com> > Cc: Lai Jiangshan <jiangshanlai@gmail.com> > Cc: Neeraj Upadhyay <neeraju@codeaurora.org> > Cc: Josh Triplett <josh@joshtriplett.org> > Cc: Joel Fernandes <joel@joelfernandes.org> > Cc: Uladzislau Rezki <urezki@gmail.com> > --- > kernel/rcu/rcu.h | 3 +++ > kernel/rcu/srcutree.c | 2 ++ > kernel/rcu/tree.c | 18 +++++++++++++++++- > 3 files changed, 22 insertions(+), 1 deletion(-) > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > index 75ed367d5b60..24db97cbf76b 100644 > --- a/kernel/rcu/rcu.h > +++ b/kernel/rcu/rcu.h > @@ -278,6 +278,7 @@ extern void resched_cpu(int cpu); > extern int rcu_num_lvls; > extern int num_rcu_lvl[]; > extern int rcu_num_nodes; > +extern bool rcu_geometry_initialized; Can this be a static local variable inside rcu_init_geometry()? After all, init_srcu_struct() isn't called all that often, and its overhead is such that an extra function call and check is going to hurt it. This of course requires removing __init from rcu_init_geometry(), but it is not all that large, so why not just remove the __init? But if we really are worried about reclaiming rcu_init_geometry()'s instructions (maybe we are?), then rcu_init_geometry() can be split into a function that just does the check (which is not __init) and the remainder of the function, which could remain __init. > static bool rcu_fanout_exact; > static int rcu_fanout_leaf; > > @@ -308,6 +309,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) > } > } > > +extern void rcu_init_geometry(void); > + > /* Returns a pointer to the first leaf rcu_node structure. */ > #define rcu_first_leaf_node() (rcu_state.level[rcu_num_lvls - 1]) > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index 108f9ca06047..05ca3c275af1 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -171,6 +171,8 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > ssp->sda = alloc_percpu(struct srcu_data); > if (!ssp->sda) > return -ENOMEM; > + if (!rcu_geometry_initialized) > + rcu_init_geometry(); With the suggested change above, this just becomes an unconditional call to rcu_init_geometry(). > init_srcu_struct_nodes(ssp); > ssp->srcu_gp_seq_needed_exp = 0; > ssp->srcu_last_gp_end = ktime_get_mono_fast_ns(); > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 740f5cd34459..b1d6e60e08d1 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -4556,17 +4556,33 @@ static void __init rcu_init_one(void) > } > } > > +bool rcu_geometry_initialized __read_mostly; This could then go away. > + > /* > * Compute the rcu_node tree geometry from kernel parameters. This cannot > * replace the definitions in tree.h because those are needed to size > * the ->node array in the rcu_state structure. > */ > -static void __init rcu_init_geometry(void) > +void rcu_init_geometry(void) > { > ulong d; > int i; > + static unsigned long old_nr_cpu_ids; > int rcu_capacity[RCU_NUM_LVLS]; And then rcu_geometry_initialized is declared static here. Or am I missing something? > + if (rcu_geometry_initialized) { > + /* > + * Arrange for warning if rcu_init_geometry() was called before > + * setup_nr_cpu_ids(). We may miss cases when > + * nr_cpus_ids == NR_CPUS but that shouldn't matter too much. > + */ > + WARN_ON_ONCE(old_nr_cpu_ids != nr_cpu_ids); > + return; > + } > + > + old_nr_cpu_ids = nr_cpu_ids; > + rcu_geometry_initialized = true; > + > /* > * Initialize any unspecified boot parameters. > * The default values of jiffies_till_first_fqs and > -- > 2.25.1 > ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] srcu: Fix broken node geometry after early ssp init 2021-04-14 15:55 ` Paul E. McKenney @ 2021-04-16 23:38 ` Frederic Weisbecker 2021-04-17 13:16 ` Frederic Weisbecker 1 sibling, 0 replies; 10+ messages in thread From: Frederic Weisbecker @ 2021-04-16 23:38 UTC (permalink / raw) To: Paul E. McKenney Cc: LKML, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes On Wed, Apr 14, 2021 at 08:55:38AM -0700, Paul E. McKenney wrote: > On Wed, Apr 14, 2021 at 03:24:12PM +0200, Frederic Weisbecker wrote: > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > > index 75ed367d5b60..24db97cbf76b 100644 > > --- a/kernel/rcu/rcu.h > > +++ b/kernel/rcu/rcu.h > > @@ -278,6 +278,7 @@ extern void resched_cpu(int cpu); > > extern int rcu_num_lvls; > > extern int num_rcu_lvl[]; > > extern int rcu_num_nodes; > > +extern bool rcu_geometry_initialized; > > Can this be a static local variable inside rcu_init_geometry()? > > After all, init_srcu_struct() isn't called all that often, and its overhead > is such that an extra function call and check is going to hurt it. This > of course requires removing __init from rcu_init_geometry(), but it is not > all that large, so why not just remove the __init? > > But if we really are worried about reclaiming rcu_init_geometry()'s > instructions (maybe we are?), then rcu_init_geometry() can be split > into a function that just does the check (which is not __init) and the > remainder of the function, which could remain __init. Indeed that makes sense, I'll move the variable inside rcu_init_geometry(). Also since rcu_init_geometry() can now be called anytime after the boot, I already removed the __init. I don't think we can do the split trick because a non-init function can't call an __init function. That would trigger a section mismatch. > > @@ -171,6 +171,8 @@ static int init_srcu_struct_fields(struct srcu_struct *ssp, bool is_static) > > ssp->sda = alloc_percpu(struct srcu_data); > > if (!ssp->sda) > > return -ENOMEM; > > + if (!rcu_geometry_initialized) > > + rcu_init_geometry(); > > With the suggested change above, this just becomes an unconditional call > to rcu_init_geometry(). Right. > > -static void __init rcu_init_geometry(void) > > +void rcu_init_geometry(void) > > { > > ulong d; > > int i; > > + static unsigned long old_nr_cpu_ids; > > int rcu_capacity[RCU_NUM_LVLS]; > > And then rcu_geometry_initialized is declared static here. > > Or am I missing something? Looks good, I'll resend with that. Thanks! > > > + if (rcu_geometry_initialized) { > > + /* > > + * Arrange for warning if rcu_init_geometry() was called before > > + * setup_nr_cpu_ids(). We may miss cases when > > + * nr_cpus_ids == NR_CPUS but that shouldn't matter too much. > > + */ > > + WARN_ON_ONCE(old_nr_cpu_ids != nr_cpu_ids); > > + return; > > + } > > + > > + old_nr_cpu_ids = nr_cpu_ids; > > + rcu_geometry_initialized = true; > > + > > /* > > * Initialize any unspecified boot parameters. > > * The default values of jiffies_till_first_fqs and > > -- > > 2.25.1 > > ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] srcu: Fix broken node geometry after early ssp init 2021-04-14 15:55 ` Paul E. McKenney 2021-04-16 23:38 ` Frederic Weisbecker @ 2021-04-17 13:16 ` Frederic Weisbecker 2021-04-18 4:46 ` Paul E. McKenney 1 sibling, 1 reply; 10+ messages in thread From: Frederic Weisbecker @ 2021-04-17 13:16 UTC (permalink / raw) To: Paul E. McKenney Cc: LKML, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes On Wed, Apr 14, 2021 at 08:55:38AM -0700, Paul E. McKenney wrote: > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > > index 75ed367d5b60..24db97cbf76b 100644 > > --- a/kernel/rcu/rcu.h > > +++ b/kernel/rcu/rcu.h > > @@ -278,6 +278,7 @@ extern void resched_cpu(int cpu); > > extern int rcu_num_lvls; > > extern int num_rcu_lvl[]; > > extern int rcu_num_nodes; > > +extern bool rcu_geometry_initialized; > > Can this be a static local variable inside rcu_init_geometry()? > > After all, init_srcu_struct() isn't called all that often, and its overhead > is such that an extra function call and check is going to hurt it. This > of course requires removing __init from rcu_init_geometry(), but it is not > all that large, so why not just remove the __init? > > But if we really are worried about reclaiming rcu_init_geometry()'s > instructions (maybe we are?), then rcu_init_geometry() can be split > into a function that just does the check (which is not __init) and the > remainder of the function, which could remain __init. There you go: --- From: Frederic Weisbecker <frederic@kernel.org> Date: Wed, 31 Mar 2021 16:10:36 +0200 Subject: [PATCH] srcu: Fix broken node geometry after early ssp init An ssp initialized before rcu_init_geometry() will have its snp hierarchy based on CONFIG_NR_CPUS. Once rcu_init_geometry() is called, the nodes distribution is shrinked and optimized toward meeting the actual possible number of CPUs detected on boot. Later on, the ssp that was initialized before rcu_init_geometry() is confused and sometimes refers to its initial CONFIG_NR_CPUS based node hierarchy, sometimes to the new num_possible_cpus() based one instead. For example each of its sdp->mynode remain backward and refer to the early node leaves that may not exist anymore. On the other hand the srcu_for_each_node_breadth_first() refers to the new node hierarchy. There are at least two bad possible outcomes to this: 1) a) A callback enqueued early on an sdp is recorded pending on sdp->mynode->srcu_data_have_cbs in srcu_funnel_gp_start() with sdp->mynode pointing to a deep leaf (say 3 levels). b) The grace period ends after rcu_init_geometry() which shrinks the nodes level to a single one. srcu_gp_end() walks through the new snp hierarchy without ever reaching the old leaves so the callback is never executed. This is easily reproduced on an 8 CPUs machine with CONFIG_NR_CPUS >= 32 and "rcupdate.rcu_self_test=1". The srcu_barrier() after early tests verification never completes and the boot hangs: [ 5413.141029] INFO: task swapper/0:1 blocked for more than 4915 seconds. [ 5413.147564] Not tainted 5.12.0-rc4+ #28 [ 5413.151927] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 5413.159753] task:swapper/0 state:D stack: 0 pid: 1 ppid: 0 flags:0x00004000 [ 5413.168099] Call Trace: [ 5413.170555] __schedule+0x36c/0x930 [ 5413.174057] ? wait_for_completion+0x88/0x110 [ 5413.178423] schedule+0x46/0xf0 [ 5413.181575] schedule_timeout+0x284/0x380 [ 5413.185591] ? wait_for_completion+0x88/0x110 [ 5413.189957] ? mark_held_locks+0x61/0x80 [ 5413.193882] ? mark_held_locks+0x61/0x80 [ 5413.197809] ? _raw_spin_unlock_irq+0x24/0x50 [ 5413.202173] ? wait_for_completion+0x88/0x110 [ 5413.206535] wait_for_completion+0xb4/0x110 [ 5413.210724] ? srcu_torture_stats_print+0x110/0x110 [ 5413.215610] srcu_barrier+0x187/0x200 [ 5413.219277] ? rcu_tasks_verify_self_tests+0x50/0x50 [ 5413.224244] ? rdinit_setup+0x2b/0x2b [ 5413.227907] rcu_verify_early_boot_tests+0x2d/0x40 [ 5413.232700] do_one_initcall+0x63/0x310 [ 5413.236541] ? rdinit_setup+0x2b/0x2b [ 5413.240207] ? rcu_read_lock_sched_held+0x52/0x80 [ 5413.244912] kernel_init_freeable+0x253/0x28f [ 5413.249273] ? rest_init+0x250/0x250 [ 5413.252846] kernel_init+0xa/0x110 [ 5413.256257] ret_from_fork+0x22/0x30 2) An ssp that gets initialized before rcu_init_geometry() and used afterward will always have stale rdp->mynode references, resulting in callbacks to be missed in srcu_gp_end(), just like in the previous scenario. Solve this with initializing nodes geometry whenever an struct srcu_state happens to be initialized before rcu_init(). This way we make sure the RCU nodes hierarchy is properly built and distributed before the nodes of an struct srcu_state are allocated. Suggested-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Uladzislau Rezki <urezki@gmail.com> --- kernel/rcu/rcu.h | 2 ++ kernel/rcu/srcutree.c | 3 +++ kernel/rcu/tree.c | 17 ++++++++++++++++- 3 files changed, 21 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h index 75ed367d5b60..edba5976ca17 100644 --- a/kernel/rcu/rcu.h +++ b/kernel/rcu/rcu.h @@ -308,6 +308,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) } } +extern void rcu_init_geometry(void); + /* Returns a pointer to the first leaf rcu_node structure. */ #define rcu_first_leaf_node() (rcu_state.level[rcu_num_lvls - 1]) diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c index 55bc9473562b..9efd5eeb5dd5 100644 --- a/kernel/rcu/srcutree.c +++ b/kernel/rcu/srcutree.c @@ -90,6 +90,9 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp) struct srcu_node *snp; struct srcu_node *snp_first; + /* First make sure the nodes hierarchy is properly built */ + rcu_init_geometry(); + /* Work out the overall tree geometry. */ ssp->level[0] = &ssp->node[0]; for (i = 1; i < rcu_num_lvls; i++) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 51600ef3fb0c..906f81786ca5 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -4617,11 +4617,26 @@ static void __init rcu_init_one(void) * replace the definitions in tree.h because those are needed to size * the ->node array in the rcu_state structure. */ -static void __init rcu_init_geometry(void) +void rcu_init_geometry(void) { ulong d; int i; + static unsigned long old_nr_cpu_ids; int rcu_capacity[RCU_NUM_LVLS]; + static bool initialized; + + if (initialized) { + /* + * Arrange for warning if rcu_init_geometry() was called before + * setup_nr_cpu_ids(). We may miss cases when + * nr_cpus_ids == NR_CPUS but that shouldn't matter too much. + */ + WARN_ON_ONCE(old_nr_cpu_ids != nr_cpu_ids); + return; + } + + old_nr_cpu_ids = nr_cpu_ids; + initialized = true; /* * Initialize any unspecified boot parameters. -- 2.25.1 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] srcu: Fix broken node geometry after early ssp init 2021-04-17 13:16 ` Frederic Weisbecker @ 2021-04-18 4:46 ` Paul E. McKenney 2021-04-19 0:23 ` Frederic Weisbecker 0 siblings, 1 reply; 10+ messages in thread From: Paul E. McKenney @ 2021-04-18 4:46 UTC (permalink / raw) To: Frederic Weisbecker Cc: LKML, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes On Sat, Apr 17, 2021 at 03:16:49PM +0200, Frederic Weisbecker wrote: > On Wed, Apr 14, 2021 at 08:55:38AM -0700, Paul E. McKenney wrote: > > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > > > index 75ed367d5b60..24db97cbf76b 100644 > > > --- a/kernel/rcu/rcu.h > > > +++ b/kernel/rcu/rcu.h > > > @@ -278,6 +278,7 @@ extern void resched_cpu(int cpu); > > > extern int rcu_num_lvls; > > > extern int num_rcu_lvl[]; > > > extern int rcu_num_nodes; > > > +extern bool rcu_geometry_initialized; > > > > Can this be a static local variable inside rcu_init_geometry()? > > > > After all, init_srcu_struct() isn't called all that often, and its overhead > > is such that an extra function call and check is going to hurt it. This > > of course requires removing __init from rcu_init_geometry(), but it is not > > all that large, so why not just remove the __init? > > > > But if we really are worried about reclaiming rcu_init_geometry()'s > > instructions (maybe we are?), then rcu_init_geometry() can be split > > into a function that just does the check (which is not __init) and the > > remainder of the function, which could remain __init. > > There you go: Queued, thank you! Thanx, Paul > --- > From: Frederic Weisbecker <frederic@kernel.org> > Date: Wed, 31 Mar 2021 16:10:36 +0200 > Subject: [PATCH] srcu: Fix broken node geometry after early ssp init > > An ssp initialized before rcu_init_geometry() will have its snp hierarchy > based on CONFIG_NR_CPUS. > > Once rcu_init_geometry() is called, the nodes distribution is shrinked > and optimized toward meeting the actual possible number of CPUs detected > on boot. > > Later on, the ssp that was initialized before rcu_init_geometry() is > confused and sometimes refers to its initial CONFIG_NR_CPUS based node > hierarchy, sometimes to the new num_possible_cpus() based one instead. > For example each of its sdp->mynode remain backward and refer to the > early node leaves that may not exist anymore. On the other hand the > srcu_for_each_node_breadth_first() refers to the new node hierarchy. > > There are at least two bad possible outcomes to this: > > 1) a) A callback enqueued early on an sdp is recorded pending on > sdp->mynode->srcu_data_have_cbs in srcu_funnel_gp_start() with > sdp->mynode pointing to a deep leaf (say 3 levels). > > b) The grace period ends after rcu_init_geometry() which shrinks the > nodes level to a single one. srcu_gp_end() walks through the new > snp hierarchy without ever reaching the old leaves so the callback > is never executed. > > This is easily reproduced on an 8 CPUs machine with > CONFIG_NR_CPUS >= 32 and "rcupdate.rcu_self_test=1". The > srcu_barrier() after early tests verification never completes and > the boot hangs: > > [ 5413.141029] INFO: task swapper/0:1 blocked for more than 4915 seconds. > [ 5413.147564] Not tainted 5.12.0-rc4+ #28 > [ 5413.151927] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 5413.159753] task:swapper/0 state:D stack: 0 pid: 1 ppid: 0 flags:0x00004000 > [ 5413.168099] Call Trace: > [ 5413.170555] __schedule+0x36c/0x930 > [ 5413.174057] ? wait_for_completion+0x88/0x110 > [ 5413.178423] schedule+0x46/0xf0 > [ 5413.181575] schedule_timeout+0x284/0x380 > [ 5413.185591] ? wait_for_completion+0x88/0x110 > [ 5413.189957] ? mark_held_locks+0x61/0x80 > [ 5413.193882] ? mark_held_locks+0x61/0x80 > [ 5413.197809] ? _raw_spin_unlock_irq+0x24/0x50 > [ 5413.202173] ? wait_for_completion+0x88/0x110 > [ 5413.206535] wait_for_completion+0xb4/0x110 > [ 5413.210724] ? srcu_torture_stats_print+0x110/0x110 > [ 5413.215610] srcu_barrier+0x187/0x200 > [ 5413.219277] ? rcu_tasks_verify_self_tests+0x50/0x50 > [ 5413.224244] ? rdinit_setup+0x2b/0x2b > [ 5413.227907] rcu_verify_early_boot_tests+0x2d/0x40 > [ 5413.232700] do_one_initcall+0x63/0x310 > [ 5413.236541] ? rdinit_setup+0x2b/0x2b > [ 5413.240207] ? rcu_read_lock_sched_held+0x52/0x80 > [ 5413.244912] kernel_init_freeable+0x253/0x28f > [ 5413.249273] ? rest_init+0x250/0x250 > [ 5413.252846] kernel_init+0xa/0x110 > [ 5413.256257] ret_from_fork+0x22/0x30 > > 2) An ssp that gets initialized before rcu_init_geometry() and used > afterward will always have stale rdp->mynode references, resulting in > callbacks to be missed in srcu_gp_end(), just like in the previous > scenario. > > Solve this with initializing nodes geometry whenever an struct srcu_state > happens to be initialized before rcu_init(). This way we make sure the > RCU nodes hierarchy is properly built and distributed before the nodes > of an struct srcu_state are allocated. > > Suggested-by: Paul E. McKenney <paulmck@kernel.org> > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> > Cc: Boqun Feng <boqun.feng@gmail.com> > Cc: Lai Jiangshan <jiangshanlai@gmail.com> > Cc: Neeraj Upadhyay <neeraju@codeaurora.org> > Cc: Josh Triplett <josh@joshtriplett.org> > Cc: Joel Fernandes <joel@joelfernandes.org> > Cc: Uladzislau Rezki <urezki@gmail.com> > --- > kernel/rcu/rcu.h | 2 ++ > kernel/rcu/srcutree.c | 3 +++ > kernel/rcu/tree.c | 17 ++++++++++++++++- > 3 files changed, 21 insertions(+), 1 deletion(-) > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > index 75ed367d5b60..edba5976ca17 100644 > --- a/kernel/rcu/rcu.h > +++ b/kernel/rcu/rcu.h > @@ -308,6 +308,8 @@ static inline void rcu_init_levelspread(int *levelspread, const int *levelcnt) > } > } > > +extern void rcu_init_geometry(void); > + > /* Returns a pointer to the first leaf rcu_node structure. */ > #define rcu_first_leaf_node() (rcu_state.level[rcu_num_lvls - 1]) > > diff --git a/kernel/rcu/srcutree.c b/kernel/rcu/srcutree.c > index 55bc9473562b..9efd5eeb5dd5 100644 > --- a/kernel/rcu/srcutree.c > +++ b/kernel/rcu/srcutree.c > @@ -90,6 +90,9 @@ static void init_srcu_struct_nodes(struct srcu_struct *ssp) > struct srcu_node *snp; > struct srcu_node *snp_first; > > + /* First make sure the nodes hierarchy is properly built */ > + rcu_init_geometry(); > + > /* Work out the overall tree geometry. */ > ssp->level[0] = &ssp->node[0]; > for (i = 1; i < rcu_num_lvls; i++) > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 51600ef3fb0c..906f81786ca5 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -4617,11 +4617,26 @@ static void __init rcu_init_one(void) > * replace the definitions in tree.h because those are needed to size > * the ->node array in the rcu_state structure. > */ > -static void __init rcu_init_geometry(void) > +void rcu_init_geometry(void) > { > ulong d; > int i; > + static unsigned long old_nr_cpu_ids; > int rcu_capacity[RCU_NUM_LVLS]; > + static bool initialized; > + > + if (initialized) { > + /* > + * Arrange for warning if rcu_init_geometry() was called before > + * setup_nr_cpu_ids(). We may miss cases when > + * nr_cpus_ids == NR_CPUS but that shouldn't matter too much. > + */ > + WARN_ON_ONCE(old_nr_cpu_ids != nr_cpu_ids); > + return; > + } > + > + old_nr_cpu_ids = nr_cpu_ids; > + initialized = true; > > /* > * Initialize any unspecified boot parameters. > -- > 2.25.1 > ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] srcu: Fix broken node geometry after early ssp init 2021-04-18 4:46 ` Paul E. McKenney @ 2021-04-19 0:23 ` Frederic Weisbecker 2021-04-19 17:00 ` Paul E. McKenney 0 siblings, 1 reply; 10+ messages in thread From: Frederic Weisbecker @ 2021-04-19 0:23 UTC (permalink / raw) To: Paul E. McKenney Cc: LKML, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes On Sat, Apr 17, 2021 at 09:46:16PM -0700, Paul E. McKenney wrote: > On Sat, Apr 17, 2021 at 03:16:49PM +0200, Frederic Weisbecker wrote: > > On Wed, Apr 14, 2021 at 08:55:38AM -0700, Paul E. McKenney wrote: > > > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > > > > index 75ed367d5b60..24db97cbf76b 100644 > > > > --- a/kernel/rcu/rcu.h > > > > +++ b/kernel/rcu/rcu.h > > > > @@ -278,6 +278,7 @@ extern void resched_cpu(int cpu); > > > > extern int rcu_num_lvls; > > > > extern int num_rcu_lvl[]; > > > > extern int rcu_num_nodes; > > > > +extern bool rcu_geometry_initialized; > > > > > > Can this be a static local variable inside rcu_init_geometry()? > > > > > > After all, init_srcu_struct() isn't called all that often, and its overhead > > > is such that an extra function call and check is going to hurt it. This > > > of course requires removing __init from rcu_init_geometry(), but it is not > > > all that large, so why not just remove the __init? > > > > > > But if we really are worried about reclaiming rcu_init_geometry()'s > > > instructions (maybe we are?), then rcu_init_geometry() can be split > > > into a function that just does the check (which is not __init) and the > > > remainder of the function, which could remain __init. > > > > There you go: > > Queued, thank you! Thanks! And please also consider "[PATCH 2/2] srcu: Early test SRCU polling start" if you want to expand testing coverage to polling. ^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH 1/2] srcu: Fix broken node geometry after early ssp init 2021-04-19 0:23 ` Frederic Weisbecker @ 2021-04-19 17:00 ` Paul E. McKenney 0 siblings, 0 replies; 10+ messages in thread From: Paul E. McKenney @ 2021-04-19 17:00 UTC (permalink / raw) To: Frederic Weisbecker Cc: LKML, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes On Mon, Apr 19, 2021 at 02:23:45AM +0200, Frederic Weisbecker wrote: > On Sat, Apr 17, 2021 at 09:46:16PM -0700, Paul E. McKenney wrote: > > On Sat, Apr 17, 2021 at 03:16:49PM +0200, Frederic Weisbecker wrote: > > > On Wed, Apr 14, 2021 at 08:55:38AM -0700, Paul E. McKenney wrote: > > > > > diff --git a/kernel/rcu/rcu.h b/kernel/rcu/rcu.h > > > > > index 75ed367d5b60..24db97cbf76b 100644 > > > > > --- a/kernel/rcu/rcu.h > > > > > +++ b/kernel/rcu/rcu.h > > > > > @@ -278,6 +278,7 @@ extern void resched_cpu(int cpu); > > > > > extern int rcu_num_lvls; > > > > > extern int num_rcu_lvl[]; > > > > > extern int rcu_num_nodes; > > > > > +extern bool rcu_geometry_initialized; > > > > > > > > Can this be a static local variable inside rcu_init_geometry()? > > > > > > > > After all, init_srcu_struct() isn't called all that often, and its overhead > > > > is such that an extra function call and check is going to hurt it. This > > > > of course requires removing __init from rcu_init_geometry(), but it is not > > > > all that large, so why not just remove the __init? > > > > > > > > But if we really are worried about reclaiming rcu_init_geometry()'s > > > > instructions (maybe we are?), then rcu_init_geometry() can be split > > > > into a function that just does the check (which is not __init) and the > > > > remainder of the function, which could remain __init. > > > > > > There you go: > > > > Queued, thank you! > > Thanks! > > And please also consider "[PATCH 2/2] srcu: Early test SRCU polling start" > if you want to expand testing coverage to polling. Ah, thank you for the reminder! Queued and pushed. Thanx, Paul ^ permalink raw reply [flat|nested] 10+ messages in thread
* [PATCH 2/2] srcu: Early test SRCU polling start 2021-04-14 13:24 [PATCH 0/2] srcu: Fix early boot hang v3 Frederic Weisbecker 2021-04-14 13:24 ` [PATCH 1/2] srcu: Fix broken node geometry after early ssp init Frederic Weisbecker @ 2021-04-14 13:24 ` Frederic Weisbecker 2021-04-14 15:56 ` Paul E. McKenney 1 sibling, 1 reply; 10+ messages in thread From: Frederic Weisbecker @ 2021-04-14 13:24 UTC (permalink / raw) To: Paul E . McKenney Cc: LKML, Frederic Weisbecker, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes Test an early call to start_poll_synchronize_srcu() and place it before the early test to call_srcu() on the same ssp. After the later call to srcu_barrier(), we expect the first grace period completion to be visible by a subsequent call to poll_state_synchronize_srcu(). Report otherwise. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Neeraj Upadhyay <neeraju@codeaurora.org> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Uladzislau Rezki <urezki@gmail.com> --- kernel/rcu/update.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index dd94a602a6d2..c21b38cc25e9 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -524,6 +524,7 @@ static void test_callback(struct rcu_head *r) } DEFINE_STATIC_SRCU(early_srcu); +static unsigned long early_srcu_cookie; struct early_boot_kfree_rcu { struct rcu_head rh; @@ -536,8 +537,10 @@ static void early_boot_test_call_rcu(void) struct early_boot_kfree_rcu *rhp; call_rcu(&head, test_callback); - if (IS_ENABLED(CONFIG_SRCU)) + if (IS_ENABLED(CONFIG_SRCU)) { + early_srcu_cookie = start_poll_synchronize_srcu(&early_srcu); call_srcu(&early_srcu, &shead, test_callback); + } rhp = kmalloc(sizeof(*rhp), GFP_KERNEL); if (!WARN_ON_ONCE(!rhp)) kfree_rcu(rhp, rh); @@ -563,6 +566,7 @@ static int rcu_verify_early_boot_tests(void) if (IS_ENABLED(CONFIG_SRCU)) { early_boot_test_counter++; srcu_barrier(&early_srcu); + WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_srcu_cookie)); } } if (rcu_self_test_counter != early_boot_test_counter) { -- 2.25.1 ^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH 2/2] srcu: Early test SRCU polling start 2021-04-14 13:24 ` [PATCH 2/2] srcu: Early test SRCU polling start Frederic Weisbecker @ 2021-04-14 15:56 ` Paul E. McKenney 0 siblings, 0 replies; 10+ messages in thread From: Paul E. McKenney @ 2021-04-14 15:56 UTC (permalink / raw) To: Frederic Weisbecker Cc: LKML, Uladzislau Rezki, Boqun Feng, Lai Jiangshan, Neeraj Upadhyay, Josh Triplett, Joel Fernandes On Wed, Apr 14, 2021 at 03:24:13PM +0200, Frederic Weisbecker wrote: > Test an early call to start_poll_synchronize_srcu() and place it before > the early test to call_srcu() on the same ssp. > > After the later call to srcu_barrier(), we expect the first grace period > completion to be visible by a subsequent call to > poll_state_synchronize_srcu(). Report otherwise. > > Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Given the first patch, this one looks good, give or take my usual editing compulsion. Thanx, Paul > Cc: Boqun Feng <boqun.feng@gmail.com> > Cc: Lai Jiangshan <jiangshanlai@gmail.com> > Cc: Neeraj Upadhyay <neeraju@codeaurora.org> > Cc: Josh Triplett <josh@joshtriplett.org> > Cc: Joel Fernandes <joel@joelfernandes.org> > Cc: Uladzislau Rezki <urezki@gmail.com> > --- > kernel/rcu/update.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c > index dd94a602a6d2..c21b38cc25e9 100644 > --- a/kernel/rcu/update.c > +++ b/kernel/rcu/update.c > @@ -524,6 +524,7 @@ static void test_callback(struct rcu_head *r) > } > > DEFINE_STATIC_SRCU(early_srcu); > +static unsigned long early_srcu_cookie; > > struct early_boot_kfree_rcu { > struct rcu_head rh; > @@ -536,8 +537,10 @@ static void early_boot_test_call_rcu(void) > struct early_boot_kfree_rcu *rhp; > > call_rcu(&head, test_callback); > - if (IS_ENABLED(CONFIG_SRCU)) > + if (IS_ENABLED(CONFIG_SRCU)) { > + early_srcu_cookie = start_poll_synchronize_srcu(&early_srcu); > call_srcu(&early_srcu, &shead, test_callback); > + } > rhp = kmalloc(sizeof(*rhp), GFP_KERNEL); > if (!WARN_ON_ONCE(!rhp)) > kfree_rcu(rhp, rh); > @@ -563,6 +566,7 @@ static int rcu_verify_early_boot_tests(void) > if (IS_ENABLED(CONFIG_SRCU)) { > early_boot_test_counter++; > srcu_barrier(&early_srcu); > + WARN_ON_ONCE(!poll_state_synchronize_srcu(&early_srcu, early_srcu_cookie)); > } > } > if (rcu_self_test_counter != early_boot_test_counter) { > -- > 2.25.1 > ^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2021-04-19 17:00 UTC | newest] Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2021-04-14 13:24 [PATCH 0/2] srcu: Fix early boot hang v3 Frederic Weisbecker 2021-04-14 13:24 ` [PATCH 1/2] srcu: Fix broken node geometry after early ssp init Frederic Weisbecker 2021-04-14 15:55 ` Paul E. McKenney 2021-04-16 23:38 ` Frederic Weisbecker 2021-04-17 13:16 ` Frederic Weisbecker 2021-04-18 4:46 ` Paul E. McKenney 2021-04-19 0:23 ` Frederic Weisbecker 2021-04-19 17:00 ` Paul E. McKenney 2021-04-14 13:24 ` [PATCH 2/2] srcu: Early test SRCU polling start Frederic Weisbecker 2021-04-14 15:56 ` Paul E. McKenney
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).