From aad653a0bc09dd4ebcb5579f9f835bbae9ef2ba3 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 19 May 2015 15:58:37 +1000 Subject: block: discard bdi_unregister() in favour of bdi_destroy() bdi_unregister() now contains very little functionality. It contains a "WARN_ON" if bdi->dev is NULL. This warning is of no real consequence as bdi->dev isn't needed by anything else in the function, and it triggers if blk_cleanup_queue() -> bdi_destroy() is called before bdi_unregister, which happens since Commit: 6cd18e711dd8 ("block: destroy bdi before blockdev is unregistered.") So this isn't wanted. It also calls bdi_set_min_ratio(). This needs to be called after writes through the bdi have all been flushed, and before the bdi is destroyed. Calling it early is better than calling it late as it frees up a global resource. Calling it immediately after bdi_wb_shutdown() in bdi_destroy() perfectly fits these requirements. So bdi_unregister() can be discarded with the important content moved to bdi_destroy(), as can the writeback_bdi_unregister event which is already not used. Reported-by: Mike Snitzer Cc: stable@vger.kernel.org (v4.0) Fixes: c4db59d31e39 ("fs: don't reassign dirty inodes to default_backing_dev_info") Fixes: 6cd18e711dd8 ("block: destroy bdi before blockdev is unregistered.") Acked-by: Peter Zijlstra (Intel) Acked-by: Dan Williams Tested-by: Nicholas Moulin Signed-off-by: NeilBrown Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- include/trace/events/writeback.h | 1 - 1 file changed, 1 deletion(-) (limited to 'include/trace') diff --git a/include/trace/events/writeback.h b/include/trace/events/writeback.h index 880dd7437172..c178d13d6f4c 100644 --- a/include/trace/events/writeback.h +++ b/include/trace/events/writeback.h @@ -250,7 +250,6 @@ DEFINE_EVENT(writeback_class, name, \ DEFINE_WRITEBACK_EVENT(writeback_nowork); DEFINE_WRITEBACK_EVENT(writeback_wake_background); DEFINE_WRITEBACK_EVENT(writeback_bdi_register); -DEFINE_WRITEBACK_EVENT(writeback_bdi_unregister); DECLARE_EVENT_CLASS(wbc_class, TP_PROTO(struct writeback_control *wbc, struct backing_dev_info *bdi), -- cgit v1.2.3 From e5feb1ebaadfb1f5f70a3591e762d780232a4f5d Mon Sep 17 00:00:00 2001 From: "Shreyas B. Prabhu" Date: Thu, 28 May 2015 15:44:16 -0700 Subject: tracing/mm: don't trace kmem_cache_free on offline cpus Since tracepoints use RCU for protection, they must not be called on offline cpus. trace_kmem_cache_free can be called on an offline cpu in this scenario caught by LOCKDEP: =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc1+ #9 Not tainted ------------------------------- include/trace/events/kmem.h:148 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.1.0-rc1+ #9 Call Trace: .dump_stack+0x98/0xd4 (unreliable) .lockdep_rcu_suspicious+0x108/0x170 .kmem_cache_free+0x344/0x4b0 .__mmdrop+0x4c/0x160 .idle_task_exit+0xf0/0x100 .pnv_smp_cpu_kill_self+0x58/0x2c0 .cpu_die+0x34/0x50 .arch_cpu_idle_dead+0x20/0x40 .cpu_startup_entry+0x708/0x7a0 .start_secondary+0x36c/0x3a0 start_secondary_prolog+0x10/0x14 Fix this by converting kmem_cache_free trace point into TRACE_EVENT_CONDITION where condition is cpu_online(smp_processor_id()) Signed-off-by: Shreyas B. Prabhu Reported-by: Aneesh Kumar K.V Reviewed-by: Preeti U Murthy Acked-by: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/trace/events/kmem.h | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) (limited to 'include/trace') diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index 81ea59812117..78efa0a197a9 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -140,11 +140,22 @@ DEFINE_EVENT(kmem_free, kfree, TP_ARGS(call_site, ptr) ); -DEFINE_EVENT(kmem_free, kmem_cache_free, +DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free, TP_PROTO(unsigned long call_site, const void *ptr), - TP_ARGS(call_site, ptr) + TP_ARGS(call_site, ptr), + + /* + * This trace can be potentially called from an offlined cpu. + * Since trace points use RCU and RCU should not be used from + * offline cpus, filter such calls out. + * While this trace can be called from a preemptable section, + * it has no impact on the condition since tasks can migrate + * only from online cpus to other online cpus. Thus its safe + * to use raw_smp_processor_id. + */ + TP_CONDITION(cpu_online(raw_smp_processor_id())) ); TRACE_EVENT(mm_page_free, -- cgit v1.2.3 From 1f0c27b50f4f2567e649f49d77daee2bbf3f40e5 Mon Sep 17 00:00:00 2001 From: "Shreyas B. Prabhu" Date: Thu, 28 May 2015 15:44:19 -0700 Subject: tracing/mm: don't trace mm_page_free on offline cpus Since tracepoints use RCU for protection, they must not be called on offline cpus. trace_mm_page_free can be called on an offline cpu in this scenario caught by LOCKDEP: =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc1+ #9 Not tainted ------------------------------- include/trace/events/kmem.h:170 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.1.0-rc1+ #9 Call Trace: .dump_stack+0x98/0xd4 (unreliable) .lockdep_rcu_suspicious+0x108/0x170 .free_pages_prepare+0x494/0x680 .free_hot_cold_page+0x50/0x280 .destroy_context+0x90/0xd0 .__mmdrop+0x58/0x160 .idle_task_exit+0xf0/0x100 .pnv_smp_cpu_kill_self+0x58/0x2c0 .cpu_die+0x34/0x50 .arch_cpu_idle_dead+0x20/0x40 .cpu_startup_entry+0x708/0x7a0 .start_secondary+0x36c/0x3a0 start_secondary_prolog+0x10/0x14 Fix this by converting mm_page_free trace point into TRACE_EVENT_CONDITION where condition is cpu_online(smp_processor_id()) Signed-off-by: Shreyas B. Prabhu Reviewed-by: Preeti U Murthy Acked-by: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/trace/events/kmem.h | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) (limited to 'include/trace') diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index 78efa0a197a9..aa863549e77a 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -158,12 +158,24 @@ DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free, TP_CONDITION(cpu_online(raw_smp_processor_id())) ); -TRACE_EVENT(mm_page_free, +TRACE_EVENT_CONDITION(mm_page_free, TP_PROTO(struct page *page, unsigned int order), TP_ARGS(page, order), + + /* + * This trace can be potentially called from an offlined cpu. + * Since trace points use RCU and RCU should not be used from + * offline cpus, filter such calls out. + * While this trace can be called from a preemptable section, + * it has no impact on the condition since tasks can migrate + * only from online cpus to other online cpus. Thus its safe + * to use raw_smp_processor_id. + */ + TP_CONDITION(cpu_online(raw_smp_processor_id())), + TP_STRUCT__entry( __field( unsigned long, pfn ) __field( unsigned int, order ) -- cgit v1.2.3 From 649b8de2f75145bf14cb1783688e16d51ac9b89a Mon Sep 17 00:00:00 2001 From: "Shreyas B. Prabhu" Date: Thu, 28 May 2015 15:44:22 -0700 Subject: tracing/mm: don't trace mm_page_pcpu_drain on offline cpus Since tracepoints use RCU for protection, they must not be called on offline cpus. trace_mm_page_pcpu_drain can be called on an offline cpu in this scenario caught by LOCKDEP: =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc1+ #9 Not tainted ------------------------------- include/trace/events/kmem.h:265 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 1 lock held by swapper/5/0: #0: (&(&zone->lock)->rlock){..-...}, at: [] .free_pcppages_bulk+0x70/0x920 stack backtrace: CPU: 5 PID: 0 Comm: swapper/5 Not tainted 4.1.0-rc1+ #9 Call Trace: .dump_stack+0x98/0xd4 (unreliable) .lockdep_rcu_suspicious+0x108/0x170 .free_pcppages_bulk+0x60c/0x920 .free_hot_cold_page+0x208/0x280 .destroy_context+0x90/0xd0 .__mmdrop+0x58/0x160 .idle_task_exit+0xf0/0x100 .pnv_smp_cpu_kill_self+0x58/0x2c0 .cpu_die+0x34/0x50 .arch_cpu_idle_dead+0x20/0x40 .cpu_startup_entry+0x708/0x7a0 .start_secondary+0x36c/0x3a0 start_secondary_prolog+0x10/0x14 Fix this by converting mm_page_pcpu_drain trace point into TRACE_EVENT_CONDITION where condition is cpu_online(smp_processor_id()) Signed-off-by: Shreyas B. Prabhu Reviewed-by: Preeti U Murthy Acked-by: Steven Rostedt Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/trace/events/kmem.h | 25 ++++++++++++++++++++++++- 1 file changed, 24 insertions(+), 1 deletion(-) (limited to 'include/trace') diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index aa863549e77a..f7554fd7fc62 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -276,12 +276,35 @@ DEFINE_EVENT(mm_page, mm_page_alloc_zone_locked, TP_ARGS(page, order, migratetype) ); -DEFINE_EVENT_PRINT(mm_page, mm_page_pcpu_drain, +TRACE_EVENT_CONDITION(mm_page_pcpu_drain, TP_PROTO(struct page *page, unsigned int order, int migratetype), TP_ARGS(page, order, migratetype), + /* + * This trace can be potentially called from an offlined cpu. + * Since trace points use RCU and RCU should not be used from + * offline cpus, filter such calls out. + * While this trace can be called from a preemptable section, + * it has no impact on the condition since tasks can migrate + * only from online cpus to other online cpus. Thus its safe + * to use raw_smp_processor_id. + */ + TP_CONDITION(cpu_online(raw_smp_processor_id())), + + TP_STRUCT__entry( + __field( unsigned long, pfn ) + __field( unsigned int, order ) + __field( int, migratetype ) + ), + + TP_fast_assign( + __entry->pfn = page ? page_to_pfn(page) : -1UL; + __entry->order = order; + __entry->migratetype = migratetype; + ), + TP_printk("page=%p pfn=%lu order=%d migratetype=%d", pfn_to_page(__entry->pfn), __entry->pfn, __entry->order, __entry->migratetype) -- cgit v1.2.3