Date:   Wed, 2 Aug 2017 12:02:21 +0530
From:   Pratyush Anand <panand@...hat.com>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     open list <linux-kernel@...r.kernel.org>
Subject: Query: rcu_sched detected stalls with function_graph tracer

Hi Steve,

I am using a 3.10 based kernel, and when I enable function_graph with one 
particular x86_64 machine, I encounter rcu_sched stall.

echo function_graph > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_on

If I use 4.13-rc2, then its better, but still goes for it after a bit of 
stressing with stressng.

It looks like that this behavior should be expected with a loaded system (like 
that of ftrace-graph tracing for all available function) which can cause RCU 
stall warning. But,I am not an expert. So, whats your opinion on it?

I tried to bisect and there was no particular function which can cause this. 
It looked like that when we had more than 5000 functions in set_ftrace_filter, 
we start getting such warnings. Tried by putting some most  hit functions like 
spin_lock* etc in set_ftrace_notrace. Still, no help.  Do you have some 
suggestion for further debugging pointers?

log with 3.10 based kernel
===============================
[  358.764071] perf: interrupt took too long (4503 > 4488), lowering 
kernel.perf_event_max_sample_rate to 44000
[  408.705034] INFO: rcu_sched detected stalls on CPUs/tasks: { 0} (detected 
by 7, t=60036 jiffies, g=21144, c=21143, q=21651)
[  408.706011] Task dump for CPU 0:
[  408.706011] swapper/0       R  running task        0     0      0 0x00000008
[  408.706011]  0000000000000003 0000000000000003 ffffffff81aaf920 
ffffffff819e4000
[  408.706011]  ffffffff819e7ed0 ffffffff816b6ef5 0000000000000000 
ffffffff81b1c820
[  408.706011]  ffffffff819e4000 ffffffff819e4000 ffffffff819e4000 
ffffffff819e4000
[  408.706011] Call Trace:
[  408.706011]  [<ffffffff816b6ef5>] ? ftrace_graph_caller+0x85/0x85
[  408.706011]  [<ffffffff81130c05>] handle_irq_event_percpu+0x55/0x80
[  408.706011]  [<ffffffff816b6ef5>] ? ftrace_graph_caller+0x85/0x85
[  408.706011]  [<ffffffff81130c6c>] handle_irq_event+0x3c/0x60
[  408.706011]  [<ffffffff816b6ef5>] ? ftrace_graph_caller+0x85/0x85
[  408.706011]  [<ffffffff8135e466>] pci_bus_read_config_dword+0x86/0xb0
[  408.706011]  [<ffffffff81692c57>] ? rest_init+0x77/0x80
[  408.706011]  [<ffffffff81b45060>] ? start_kernel+0x439/0x45a
[  408.706011]  [<ffffffff81b44a30>] ? repair_env_string+0x5c/0x5c
[  408.706011]  [<ffffffff81b44120>] ? early_idt_handler_array+0x120/0x120
[  408.706011]  [<ffffffff81b445ef>] ? x86_64_start_reservations+0x24/0x26
[  408.706011]  [<ffffffff81b44740>] ? x86_64_start_kernel+0x14f/0x172
[  377.243167] perf: interrupt took too long (5741 > 5628), lowering 
kernel.perf_event_max_sample_rate to 34000
[  437.522697] perf: interrupt took too long (8551 > 7176), lowering 
kernel.perf_event_max_sample_rate to 23000
[  463.908115] perf: interrupt took too long (11374 > 10688), lowering 
kernel.perf_event_max_sample_rate to 17000
[  480.954277] INFO: task yum:6726 blocked for more than 120 seconds.
[  480.991431] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables 
this message.
[  481.038470] yum             D ffff880467bebf40     0  6726   6714 0x00000080
[  481.081174]  ffff88006489b850 0000000000000082 ffff880467bebf40 
ffff88006489bfd8
[  481.126085]  ffff88006489bfd8 ffff88006489bfd8 ffff880467bebf40 
ffff8802772656b0
[  481.171087]  7fffffffffffffff 0000000000000002 0000000000000000 
ffff880467bebf40
[  481.216034] Call Trace:
[  481.230832]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.266435]  [<ffffffff816a94c9>] schedule+0x29/0x70
[  481.296290]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.331966]  [<ffffffff816a6fd9>] schedule_timeout+0x239/0x2c0
[  481.367082]  [<ffffffff8105bdd6>] ? prepare_ftrace_return+0xb6/0xe0
[  481.404850]  [<ffffffff816a88c1>] ? __down_common+0x104/0x104
[  481.439492]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.475091]  [<ffffffff816a8867>] __down_common+0xaa/0x104
[  481.508098]  [<ffffffff816b6ef5>] ? ftrace_graph_caller+0x85/0x85
[  481.544778]  [<ffffffff810b6691>] down+0x41/0x50
[  481.577943]  [<ffffffff816a88de>] __down+0x1d/0x1f
[  481.611734]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.652576]  [<ffffffffc02c421c>] xfs_buf_lock+0x3c/0xd0 [xfs]
[  481.693178]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.734216]  [<ffffffffc02c4420>] _xfs_buf_find+0x170/0x330 [xfs]
[  481.775910]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.816266]  [<ffffffffc02c460a>] xfs_buf_get_map+0x2a/0x240 [xfs]
[  481.859119]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.899431]  [<ffffffffc02c5180>] xfs_buf_read_map+0x30/0x160 [xfs]
[  481.941875]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  481.982192]  [<ffffffffc02f4ea1>] xfs_trans_read_buf_map+0x211/0x400 [xfs]
[  482.027938]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.068655]  [<ffffffffc02b8d6e>] xfs_imap_to_bp+0x6e/0xf0 [xfs]
[  482.109275]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.149375]  [<ffffffffc02d5aa5>] xfs_iunlink_remove+0x295/0x3c0 [xfs]
[  482.193561]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.233577]  [<ffffffffc02d9157>] xfs_ifree+0x47/0x100 [xfs]
[  482.272198]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.312544]  [<ffffffffc02d92e1>] xfs_inactive_ifree+0xd1/0x230 [xfs]
[  482.355816]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.395936]  [<ffffffffc02d94cb>] xfs_inactive+0x8b/0x130 [xfs]
[  482.436204]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.477110]  [<ffffffffc02dff65>] xfs_fs_destroy_inode+0x95/0x180 [xfs]
[  482.521397]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.562184]  [<ffffffff8121d548>] destroy_inode+0x38/0x60
[  482.599372]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.639831]  [<ffffffff8121d67a>] evict+0x10a/0x180
[  482.673827]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.714694]  [<ffffffff8121df29>] iput+0xf9/0x190
[  482.748414]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.789294]  [<ffffffff812186c8>] dentry_kill+0x168/0x1b0
[  482.827374]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.868003]  [<ffffffff81212a68>] SYSC_renameat2+0x518/0x5a0
[  482.906672]  [<ffffffff8121876e>] dput+0x5e/0xd0
[  482.938986]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  482.979490]  [<ffffffff8121397e>] SyS_rename+0x1e/0x20
[  483.016292]  [<ffffffff81158fcf>] ? ftrace_push_return_trace+0x4f/0xe0
[  483.060909]  [<ffffffff81213930>] ? SyS_link+0x20/0x20
[  483.096075]  [<ffffffff8121397e>] ? SyS_rename+0x1e/0x20
[  483.132925]  [<ffffffff8105bdd6>] ? prepare_ftrace_return+0xb6/0xe0
[  483.174945]  [<ffffffff81213930>] ? SyS_link+0x20/0x20
[  483.210469]  [<ffffffff8115947b>] ? __trace_graph_return+0x9b/0xb0
[  483.252601]  [<ffffffff8121393e>] SyS_renameat2+0xe/0x10
[  483.288881]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  483.328689]  [<ffffffff816b4fc9>] system_call_fastpath+0x16/0x1b
[  483.369480]  [<ffffffff816b6ef5>] ftrace_graph_caller+0x85/0x85
[  507.786060] perf: interrupt took too long (14339 > 14217), lowering 
kernel.perf_event_max_sample_rate to 13000
[  546.740390] perf: interrupt took too long (18151 > 17923), lowering 
kernel.perf_event_max_sample_rate to 11000
[  588.710897] INFO: rcu_sched detected stalls on CPUs/tasks: { 0} (detected 
by 7, t=240042 jiffies, g=21144, c=21143, q=23204)
[  588.711872] Task dump for CPU 0:
[  588.711872] swapper/0       R  running task        0     0      0 0x00000008
[  588.711872]  0000000000000003 0000000000000003 ffffffff81aaf920 
ffffffff819e4000
[  588.711872]  ffffffff819e7ed0 ffffffff816b6ef5 0000000000000000 
ffffffff81b1c820
[  588.711872]  ffffffff819e4000 ffffffff819e4000 ffffffff819e4000 
ffffffff819e4000
[  588.711872] Call Trace:
[  588.711872]  [<ffffffff816b6ef5>] ? ftrace_graph_caller+0x85/0x85
[  588.711872]  [<ffffffff81130c05>] handle_irq_event_percpu+0x55/0x80
[  588.711872]  [<ffffffff816b6ef5>] ? ftrace_graph_caller+0x85/0x85
[  588.711872]  [<ffffffff81130c6c>] handle_irq_event+0x3c/0x60
[  588.711872]  [<ffffffff816b6ef5>] ? ftrace_graph_caller+0x85/0x85
[  588.711872]  [<ffffffff81130c6c>] handle_irq_event+0x3c/0x60
[  588.711872]  [<ffffffff81692c57>] ? rest_init+0x77/0x80
[  588.711872]  [<ffffffff81b45060>] ? start_kernel+0x439/0x45a
[  588.711872]  [<ffffffff81b44a30>] ? repair_env_string+0x5c/0x5c
[  588.711872]  [<ffffffff81b44120>] ? early_idt_handler_array+0x120/0x120
[  588.711872]  [<ffffffff81b445ef>] ? x86_64_start_reservations+0x24/0x26
[  588.711872]  [<ffffffff81b44740>] ? x86_64_start_kernel+0x14f/0x172
[-- MARK -- Wed Jul 12 02:45:00 2017]

log with 4.13-rc2 kernel
=============================

[  876.272025] INFO: rcu_sched detected stalls on CPUs/tasks:
[  876.272027] 	0-...: (1 GPs behind) idle=992/140000000000000/0 
softirq=66236/66237 fqs=11905
[  876.272027] 	(detected by 12, t=60002 jiffies, g=20604, c=20603, q=23819)
[  876.272027] Sending NMI from CPU 12 to CPUs 0:
[  876.272027] NMI backtrace for cpu 0
[  876.272027] CPU: 0 PID: 2106 Comm: stress Not tainted 4.13.0-rc2 #1
[  876.272027] Hardware name: XXXXXXXXXXXXXXXXX
[  876.272027] task: ffff9484e3a52c00 task.stack: ffffaa1c08888000
[  876.272027] RIP: 0010:delay_tsc+0x23/0x60
[  876.272027] RSP: 0000:ffffaa1c0888b768 EFLAGS: 00000083
[  876.272027] RAX: 00000000000007a4 RBX: ffffffffb9f48d40 RCX: 000001eec7b47589
[  876.272027] RDX: 000001eec7b47d2d RSI: 0000000000000000 RDI: 00000000000007d1
[  876.272027] RBP: ffffaa1c0888b768 R08: ffff94820fc08890 R09: 000000002ce120d1
[  876.272027] R10: 0000000497700000 R11: ffff9482f6c7c580 R12: 00000000000026f2
[  876.272027] R13: 0000000000000020 R14: ffffffffb9ce4ad1 R15: ffffffffb9f48d40
[  876.272027] FS:  00007fdb22cf9740(0000) GS:ffff9482f6200000(0000) 
knlGS:0000000000000000
[  876.272027] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  876.272027] CR2: 00007f4dfe401010 CR3: 00000004656ef000 CR4: 00000000000006f0
[  876.272027] Call Trace:
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  __const_udelay+0x32/0x40
[  876.272027]  wait_for_xmitr+0x2c/0xa0
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  serial8250_console_putchar+0x1c/0x30
[  876.272027]  ? wait_for_xmitr+0xa0/0xa0
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  uart_console_write+0x31/0x70
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  serial8250_console_write+0xd7/0x290
[  876.272027]  ? serial8250_console_write+0x5/0x290
[  876.272027]  ? ftrace_return_to_handler+0x9d/0xf0
[  876.272027]  ? univ8250_console_write+0x5/0x30
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  univ8250_console_write+0x26/0x30
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  console_unlock+0x3e6/0x4c0
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  vprintk_emit+0x2f5/0x3a0
[  876.272027]  ? vprintk_emit+0x5/0x3a0
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  vprintk_default+0x29/0x50
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  vprintk_func+0x27/0x60
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  printk+0x58/0x6f
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  show_free_areas+0x255/0xa40
[  876.272027]  ? ftrace_graph_caller+0x78/0xa8
[  876.272027]  ? __trace_graph_return+0x88/0x90
[  876.272027]  ? ftrace_return_to_handler+0x9d/0xf0
[  876.272027]  ? show_free_areas+0x5/0xa40
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  show_mem+0x2b/0xf0
[  876.272027]  warn_alloc+0x198/0x1c0
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  __alloc_pages_slowpath+0x353/0xb90
[  876.272027]  ? __trace_graph_return+0x88/0x90
[  876.272027]  ? __alloc_pages_nodemask+0x102/0x290
[  876.272027]  ? ftrace_return_to_handler+0x9d/0xf0
[  876.272027]  __alloc_pages_nodemask+0x267/0x290
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  alloc_pages_vma+0x7f/0x180
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  __handle_mm_fault+0xbeb/0x1150
[  876.272027]  ? __trace_graph_return+0x88/0x90
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  handle_mm_fault+0xd1/0x230
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  __do_page_fault+0x22a/0x4a0
[  876.272027]  ? ftrace_graph_caller+0xa8/0xa8
[  876.272027]  do_page_fault+0x30/0x80
[  876.272027]  ? return_to_handler+0x15/0x27
[  876.272027]  page_fault+0x28/0x30
[  876.272027] RIP: 0033:0x403072
[  876.272027] RSP: 002b:00007fff358a2590 EFLAGS: 00010202
[  876.272027] RAX: 00007fdb19e8e010 RBX: 0000000000000000 RCX: 00007fdb12420010
[  876.272027] RDX: 0000000007a6e000 RSI: 0000000010001000 RDI: 0000000000000000
[  876.272027] RBP: 00007fff358a25d0 R08: ffffffffffffffff R09: 0000000010000000
[  876.272027] R10: 0000000000000022 R11: 0000000000001000 R12: 0000000000400dc0
[  876.272027] R13: 00007fff358a27e0 R14: 0000000000000000 R15: 0000000000000000
[  876.272027] Code: c3 0f 1f 80 00 00 00 00 e8 7b 1c 01 00 55 48 89 e5 65 8b 
35 d0 be ca 46 0f ae e8 0f 31 48 89 d1 48 c1 e1 20 48 09 c1 eb 0d f3 90 <65> 
8b 05 b6 be ca 46 39 c6 75 19 0f ae e8 0f 31 48 c1 e2 20 48
[  876.319103] INFO: NMI handler (nmi_cpu_backtrace_handler) took too long to 
run: 1.808 msecs
[  877.920915] stress: page allocation stalls for 11490ms, order:0, 
mode:0x14280ca(GFP_HIGHUSER_MOVABLE|__GFP_ZERO), nodemask=(null)
[  877.920971] stress cpuset=/ mems_allowed=0-1
[  877.921094] CPU: 18 PID: 2085 Comm: stress Not tainted 4.13.0-rc2 #1
[  877.921108] Hardware name: XXXXXXXXXX
[  877.921122] Call Trace:
[  877.921170]  ? ftrace_graph_caller+0xa8/0xa8
[  877.921193]  dump_stack+0x63/0x89
[  877.921237]  warn_alloc+0x114/0x1c0
[  877.921352]  ? ftrace_graph_caller+0xa8/0xa8
[  877.921372]  __alloc_pages_slowpath+0x353/0xb90
[  877.921444]  ? __trace_graph_return+0x88/0x90
[  877.921489]  ? __alloc_pages_nodemask+0x102/0x290
[  877.921520]  ? ftrace_return_to_handler+0x9d/0xf0
[  877.921599]  __alloc_pages_nodemask+0x267/0x290
[  877.921701]  ? ftrace_graph_caller+0xa8/0xa8
[  877.921726]  alloc_pages_vma+0x7f/0x180
[  877.921790]  ? ftrace_graph_caller+0xa8/0xa8
[  877.921812]  __handle_mm_fault+0xbeb/0x1150
[  877.921839]  ? __trace_graph_return+0x88/0x90
[  877.921968]  ? ftrace_graph_caller+0xa8/0xa8
[  877.921986]  handle_mm_fault+0xd1/0x230
[  877.922028]  ? ftrace_graph_caller+0xa8/0xa8
[  877.922028]  __do_page_fault+0x22a/0x4a0
[  877.922028]  ? ftrace_graph_caller+0xa8/0xa8
[  877.922028]  do_page_fault+0x30/0x80
[  877.922028]  ? return_to_handler+0x15/0x27
[  877.922028]  page_fault+0x28/0x30
[  877.922028] RIP: 0033:0x403072
[  877.922028] RSP: 002b:00007fff358a2590 EFLAGS: 00010202
[  877.922028] RAX: 00007fdb1f99a010 RBX: 0000000000000000 RCX: 00007fdb12420010
[  877.922028] RDX: 000000000d57a000 RSI: 0000000010001000 RDI: 0000000000000000
[  877.922028] RBP: 00007fff358a25d0 R08: ffffffffffffffff R09: 0000000010000000
[  877.922028] R10: 0000000000000022 R11: 0000000000001000 R12: 0000000000400dc0
[  877.922028] R13: 00007fff358a27e0 R14: 0000000000000000 R15: 0000000000000000
[  877.922541] warn_alloc_show_mem: 1 callbacks suppressed
[  877.922554] Mem-Info:
[  877.922594] active_anon:3380619 inactive_anon:424654 isolated_anon:27399

--
Regards
Pratyush

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