From: Jungseok Lee <jungseoklee85@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: AKASHI Takahiro <takahiro.akashi@linaro.org>,
catalin.marinas@arm.com, will.deacon@arm.com, olof@lixom.net,
broonie@kernel.org, david.griego@linaro.org,
linux-arm-kernel@lists.infradead.org,
linux-kernel@vger.kernel.org
Subject: Re: [RFC 2/3] arm64: refactor save_stack_trace()
Date: Fri, 17 Jul 2015 00:01:25 +0900 [thread overview]
Message-ID: <12F47692-3010-4886-B87D-3D7820609177@gmail.com> (raw)
In-Reply-To: <20150716102405.2cc8c406@gandalf.local.home>
On Jul 16, 2015, at 11:24 PM, Steven Rostedt wrote:
Hi, Steve
> On Thu, 16 Jul 2015 22:29:05 +0900
> Jungseok Lee <jungseoklee85@gmail.com> wrote:
[ snip ]
>> The data looks odd in two points.
>> 1) the number of entry
>> There is a mismatch between start token and real data
>
> Yep, good catch. As soon as I read that, I realized exactly what the
> issue was ;-)
>
>>
>> 2) 80-byte gap
>> stack_max_size is not aligned with "Depth" field of the first entry of stack_trace.
>>
>> IMHO, two items are not considered in this series as digging them out.
>>
>> 1) skipped entries
>> As x variable is introduced in Steve's patch, it is needed to track down
>> how many entries are recorded in both stack_dump_trace and stack_dump_index.
>
> Yep.
>
>>
>> 2) max_stack_trace.skip value
>> max_stack_trace.skip is 0 as applying Steve's patch. The above gap could be
>> observed unless the value is not considered in arch code. In the above example,
>> 80-byte gap is save_stack_trace function in arch/arm64/kernel/stacktrace.c.
>>
>> As applying the following fix, stack_trace and stack_max_size are okay.
>> However, I'm not sure which code, arch or generic ftrace, should handle trace->skip.
>> The latter one is responsible for it under current implementation, not Steve's change.
>>
>> Please correct me if I am wrong.
>
> No, it's a bug in my patch. I'll make an update.
>
> Does this new patch fix it for you?
I've gathered stack tracer data with your update.
1) stack_trace
Depth Size Location (35 entries)
----- ---- --------
0) 4424 16 put_cpu_partial+0x28/0x1d0
1) 4408 80 get_partial_node.isra.64+0x13c/0x344
2) 4328 256 __slab_alloc.isra.65.constprop.67+0xd8/0x37c
3) 4072 32 kmem_cache_alloc+0x258/0x294
4) 4040 304 __alloc_skb+0x48/0x180
5) 3736 96 alloc_skb_with_frags+0x74/0x234
6) 3640 112 sock_alloc_send_pskb+0x1d0/0x294
7) 3528 160 sock_alloc_send_skb+0x44/0x54
8) 3368 64 __ip_append_data.isra.40+0x78c/0xb48
9) 3304 224 ip_append_data.part.42+0x98/0xe8
10) 3080 112 ip_append_data+0x68/0x7c
11) 2968 96 icmp_push_reply+0x7c/0x144
12) 2872 96 icmp_send+0x3c0/0x3c8
13) 2776 192 __udp4_lib_rcv+0x5b8/0x684
14) 2584 96 udp_rcv+0x2c/0x3c
15) 2488 32 ip_local_deliver+0xa0/0x224
16) 2456 48 ip_rcv+0x360/0x57c
17) 2408 64 __netif_receive_skb_core+0x4d0/0x80c
18) 2344 128 __netif_receive_skb+0x24/0x84
19) 2216 32 process_backlog+0x9c/0x15c
20) 2184 80 net_rx_action+0x1ec/0x32c
21) 2104 160 __do_softirq+0x114/0x2f0
22) 1944 128 do_softirq+0x60/0x68
23) 1816 32 __local_bh_enable_ip+0xb0/0xd4
24) 1784 32 ip_finish_output+0x1f4/0xabc
25) 1752 96 ip_output+0xf0/0x120
26) 1656 64 ip_local_out_sk+0x44/0x54
27) 1592 32 ip_send_skb+0x24/0xbc
28) 1560 48 udp_send_skb+0x1b4/0x2f4
29) 1512 80 udp_sendmsg+0x2a8/0x7a0
30) 1432 272 inet_sendmsg+0xa0/0xd0
31) 1160 48 sock_sendmsg+0x30/0x78
32) 1112 32 ___sys_sendmsg+0x15c/0x26c
33) 1080 400 __sys_sendmmsg+0x94/0x180
34) 680 320 SyS_sendmmsg+0x38/0x54
35) 360 360 el0_svc_naked+0x20/0x28
2) stack_max_size
4504
In case of the number of entries, the following diff might be needed
as I suggested in the previous reply. ;)
----8<----
@@ -330,7 +333,7 @@ static int t_show(struct seq_file *m, void *v)
seq_printf(m, " Depth Size Location"
" (%d entries)\n"
" ----- ---- --------\n",
- max_stack_trace.nr_entries - 1);
+ max_stack_trace.nr_entries);
if (!stack_tracer_enabled && !max_stack_size)
print_disabled(m);
----8<----
However, 80-byte gap still appears.
Since max_stack_trace.skip is 3 in your update, save_stack_trace in arm64
should be refactored to align with this value.
max_stack_trace.skip should be set to 4 if AKASHI's [RFC 2/3] patch is merged.
However, arch code is supposed to follow generic framework's rule in this case.
Isn't it?
Best Regards
Jungseok Lee
WARNING: multiple messages have this Message-ID (diff)
From: jungseoklee85@gmail.com (Jungseok Lee)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 2/3] arm64: refactor save_stack_trace()
Date: Fri, 17 Jul 2015 00:01:25 +0900 [thread overview]
Message-ID: <12F47692-3010-4886-B87D-3D7820609177@gmail.com> (raw)
In-Reply-To: <20150716102405.2cc8c406@gandalf.local.home>
On Jul 16, 2015, at 11:24 PM, Steven Rostedt wrote:
Hi, Steve
> On Thu, 16 Jul 2015 22:29:05 +0900
> Jungseok Lee <jungseoklee85@gmail.com> wrote:
[ snip ]
>> The data looks odd in two points.
>> 1) the number of entry
>> There is a mismatch between start token and real data
>
> Yep, good catch. As soon as I read that, I realized exactly what the
> issue was ;-)
>
>>
>> 2) 80-byte gap
>> stack_max_size is not aligned with "Depth" field of the first entry of stack_trace.
>>
>> IMHO, two items are not considered in this series as digging them out.
>>
>> 1) skipped entries
>> As x variable is introduced in Steve's patch, it is needed to track down
>> how many entries are recorded in both stack_dump_trace and stack_dump_index.
>
> Yep.
>
>>
>> 2) max_stack_trace.skip value
>> max_stack_trace.skip is 0 as applying Steve's patch. The above gap could be
>> observed unless the value is not considered in arch code. In the above example,
>> 80-byte gap is save_stack_trace function in arch/arm64/kernel/stacktrace.c.
>>
>> As applying the following fix, stack_trace and stack_max_size are okay.
>> However, I'm not sure which code, arch or generic ftrace, should handle trace->skip.
>> The latter one is responsible for it under current implementation, not Steve's change.
>>
>> Please correct me if I am wrong.
>
> No, it's a bug in my patch. I'll make an update.
>
> Does this new patch fix it for you?
I've gathered stack tracer data with your update.
1) stack_trace
Depth Size Location (35 entries)
----- ---- --------
0) 4424 16 put_cpu_partial+0x28/0x1d0
1) 4408 80 get_partial_node.isra.64+0x13c/0x344
2) 4328 256 __slab_alloc.isra.65.constprop.67+0xd8/0x37c
3) 4072 32 kmem_cache_alloc+0x258/0x294
4) 4040 304 __alloc_skb+0x48/0x180
5) 3736 96 alloc_skb_with_frags+0x74/0x234
6) 3640 112 sock_alloc_send_pskb+0x1d0/0x294
7) 3528 160 sock_alloc_send_skb+0x44/0x54
8) 3368 64 __ip_append_data.isra.40+0x78c/0xb48
9) 3304 224 ip_append_data.part.42+0x98/0xe8
10) 3080 112 ip_append_data+0x68/0x7c
11) 2968 96 icmp_push_reply+0x7c/0x144
12) 2872 96 icmp_send+0x3c0/0x3c8
13) 2776 192 __udp4_lib_rcv+0x5b8/0x684
14) 2584 96 udp_rcv+0x2c/0x3c
15) 2488 32 ip_local_deliver+0xa0/0x224
16) 2456 48 ip_rcv+0x360/0x57c
17) 2408 64 __netif_receive_skb_core+0x4d0/0x80c
18) 2344 128 __netif_receive_skb+0x24/0x84
19) 2216 32 process_backlog+0x9c/0x15c
20) 2184 80 net_rx_action+0x1ec/0x32c
21) 2104 160 __do_softirq+0x114/0x2f0
22) 1944 128 do_softirq+0x60/0x68
23) 1816 32 __local_bh_enable_ip+0xb0/0xd4
24) 1784 32 ip_finish_output+0x1f4/0xabc
25) 1752 96 ip_output+0xf0/0x120
26) 1656 64 ip_local_out_sk+0x44/0x54
27) 1592 32 ip_send_skb+0x24/0xbc
28) 1560 48 udp_send_skb+0x1b4/0x2f4
29) 1512 80 udp_sendmsg+0x2a8/0x7a0
30) 1432 272 inet_sendmsg+0xa0/0xd0
31) 1160 48 sock_sendmsg+0x30/0x78
32) 1112 32 ___sys_sendmsg+0x15c/0x26c
33) 1080 400 __sys_sendmmsg+0x94/0x180
34) 680 320 SyS_sendmmsg+0x38/0x54
35) 360 360 el0_svc_naked+0x20/0x28
2) stack_max_size
4504
In case of the number of entries, the following diff might be needed
as I suggested in the previous reply. ;)
----8<----
@@ -330,7 +333,7 @@ static int t_show(struct seq_file *m, void *v)
seq_printf(m, " Depth Size Location"
" (%d entries)\n"
" ----- ---- --------\n",
- max_stack_trace.nr_entries - 1);
+ max_stack_trace.nr_entries);
if (!stack_tracer_enabled && !max_stack_size)
print_disabled(m);
----8<----
However, 80-byte gap still appears.
Since max_stack_trace.skip is 3 in your update, save_stack_trace in arm64
should be refactored to align with this value.
max_stack_trace.skip should be set to 4 if AKASHI's [RFC 2/3] patch is merged.
However, arch code is supposed to follow generic framework's rule in this case.
Isn't it?
Best Regards
Jungseok Lee
next prev parent reply other threads:[~2015-07-16 15:01 UTC|newest]
Thread overview: 106+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-13 5:29 [RFC 0/3] arm64: ftrace: fix incorrect output from stack tracer AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 1/3] ftrace: adjust a function's pc to search for in check_stack() for arm64 AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 15:24 ` Steven Rostedt
2015-07-13 15:24 ` Steven Rostedt
2015-07-15 0:22 ` AKASHI Takahiro
2015-07-15 0:22 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 2/3] arm64: refactor save_stack_trace() AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-14 12:47 ` Jungseok Lee
2015-07-14 12:47 ` Jungseok Lee
2015-07-14 13:31 ` Steven Rostedt
2015-07-14 13:31 ` Steven Rostedt
2015-07-15 0:20 ` AKASHI Takahiro
2015-07-15 0:20 ` AKASHI Takahiro
2015-07-15 2:51 ` Steven Rostedt
2015-07-15 2:51 ` Steven Rostedt
2015-07-15 11:41 ` AKASHI Takahiro
2015-07-15 11:41 ` AKASHI Takahiro
2015-07-15 14:55 ` Steven Rostedt
2015-07-15 14:55 ` Steven Rostedt
2015-07-15 16:13 ` Steven Rostedt
2015-07-15 16:13 ` Steven Rostedt
2015-07-16 0:27 ` AKASHI Takahiro
2015-07-16 0:27 ` AKASHI Takahiro
2015-07-16 1:08 ` AKASHI Takahiro
2015-07-16 1:08 ` AKASHI Takahiro
2015-07-16 1:38 ` Steven Rostedt
2015-07-16 1:38 ` Steven Rostedt
2015-07-17 10:46 ` Will Deacon
2015-07-17 10:46 ` Will Deacon
2015-07-16 13:29 ` Jungseok Lee
2015-07-16 13:29 ` Jungseok Lee
2015-07-16 13:54 ` Jungseok Lee
2015-07-16 13:54 ` Jungseok Lee
2015-07-16 14:24 ` Steven Rostedt
2015-07-16 14:24 ` Steven Rostedt
2015-07-16 15:01 ` Jungseok Lee [this message]
2015-07-16 15:01 ` Jungseok Lee
2015-07-16 15:31 ` Steven Rostedt
2015-07-16 15:31 ` Steven Rostedt
2015-07-16 15:52 ` Jungseok Lee
2015-07-16 15:52 ` Jungseok Lee
2015-07-16 20:22 ` Steven Rostedt
2015-07-16 20:22 ` Steven Rostedt
2015-07-17 2:49 ` AKASHI Takahiro
2015-07-17 2:49 ` AKASHI Takahiro
2015-07-17 3:21 ` Steven Rostedt
2015-07-17 3:21 ` Steven Rostedt
2015-07-16 16:16 ` Steven Rostedt
2015-07-16 16:16 ` Steven Rostedt
2015-07-17 12:40 ` Mark Rutland
2015-07-17 12:40 ` Mark Rutland
2015-07-17 12:51 ` Steven Rostedt
2015-07-17 12:51 ` Steven Rostedt
2015-07-17 13:00 ` Steven Rostedt
2015-07-17 13:00 ` Steven Rostedt
2015-07-17 14:28 ` Jungseok Lee
2015-07-17 14:28 ` Jungseok Lee
2015-07-17 14:41 ` Steven Rostedt
2015-07-17 14:41 ` Steven Rostedt
2015-07-17 14:59 ` Jungseok Lee
2015-07-17 14:59 ` Jungseok Lee
2015-07-17 15:34 ` Jungseok Lee
2015-07-17 15:34 ` Jungseok Lee
2015-07-17 16:01 ` Steven Rostedt
2015-07-17 16:01 ` Steven Rostedt
2015-07-20 16:20 ` Will Deacon
2015-07-20 16:20 ` Will Deacon
2015-07-20 23:53 ` AKASHI Takahiro
2015-07-20 23:53 ` AKASHI Takahiro
2015-07-21 10:26 ` AKASHI Takahiro
2015-07-21 10:26 ` AKASHI Takahiro
2015-07-21 14:34 ` Jungseok Lee
2015-07-21 14:34 ` Jungseok Lee
2015-08-03 9:09 ` Will Deacon
2015-08-03 9:09 ` Will Deacon
2015-08-03 14:01 ` Steven Rostedt
2015-08-03 14:01 ` Steven Rostedt
2015-08-03 14:04 ` Will Deacon
2015-08-03 14:04 ` Will Deacon
2015-08-03 16:30 ` Jungseok Lee
2015-08-03 16:30 ` Jungseok Lee
2015-08-03 16:57 ` Steven Rostedt
2015-08-03 16:57 ` Steven Rostedt
2015-08-03 17:22 ` Jungseok Lee
2015-08-03 17:22 ` Jungseok Lee
2015-08-03 17:32 ` Steven Rostedt
2015-08-03 17:32 ` Steven Rostedt
2015-08-04 7:41 ` AKASHI Takahiro
2015-08-04 7:41 ` AKASHI Takahiro
2015-07-17 2:04 ` AKASHI Takahiro
2015-07-17 2:04 ` AKASHI Takahiro
2015-07-17 14:38 ` Jungseok Lee
2015-07-17 14:38 ` Jungseok Lee
2015-07-16 14:28 ` Mark Rutland
2015-07-16 14:28 ` Mark Rutland
2015-07-16 14:34 ` Steven Rostedt
2015-07-16 14:34 ` Steven Rostedt
2015-07-17 2:09 ` AKASHI Takahiro
2015-07-17 2:09 ` AKASHI Takahiro
2015-07-13 5:29 ` [RFC 3/3] arm64: ftrace: mcount() should not create a stack frame AKASHI Takahiro
2015-07-13 5:29 ` AKASHI Takahiro
2015-07-13 15:01 ` [RFC 0/3] arm64: ftrace: fix incorrect output from stack tracer Jungseok Lee
2015-07-13 15:01 ` Jungseok Lee
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