diff mbox series

[v3,2/2] mm: mmap: add trace point of vm_unmapped_area

Message ID 20200320055823.27089-3-jaewon31.kim@samsung.com (mailing list archive)
State New, archived
Headers show
Series mm: mmap: add mmap trace point | expand

Commit Message

Jaewon Kim March 20, 2020, 5:58 a.m. UTC
Even on 64 bit kernel, the mmap failure can happen for a 32 bit task.
Virtual memory space shortage of a task on mmap is reported to userspace
as -ENOMEM. It can be confused as physical memory shortage of overall
system.

The vm_unmapped_area can be called to by some drivers or other kernel
core system like filesystem. In my platform, GPU driver calls to
vm_unmapped_area and the driver returns -ENOMEM even in GPU side
shortage. It can be hard to distinguish which code layer returns the
-ENOMEM.

Create mmap trace file and add trace point of vm_unmapped_area.

i.e.)
277.156599: vm_unmapped_area: addr=77e0d03000 err=0 total_vm=0x17014b flags=0x1 len=0x400000 lo=0x8000 hi=0x7878c27000 mask=0x0 ofs=0x1
342.838740: vm_unmapped_area: addr=0 err=-12 total_vm=0xffb08 flags=0x0 len=0x100000 lo=0x40000000 hi=0xfffff000 mask=0x0 ofs=0x22

Signed-off-by: Jaewon Kim <jaewon31.kim@samsung.com>
---
v3: reduce fast_assign and print format
v2: use trace point rather than printk with ratelimit
v1: use printk with ratelimit 
---
 include/trace/events/mmap.h | 48 +++++++++++++++++++++++++++++++++++++++++++++
 mm/mmap.c                   | 12 ++++++++++--
 2 files changed, 58 insertions(+), 2 deletions(-)
 create mode 100644 include/trace/events/mmap.h

Comments

Matthew Wilcox March 29, 2020, 4:08 p.m. UTC | #1
On Fri, Mar 20, 2020 at 02:58:23PM +0900, Jaewon Kim wrote:
> +	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",

Shouldn't addr be printed as 0x%lx?  I think it's arguable whether to print
len as %ld or 0x%lx.
Matthew Wilcox March 29, 2020, 4:14 p.m. UTC | #2
On Fri, Mar 20, 2020 at 02:58:23PM +0900, Jaewon Kim wrote:
> +	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
> +		IS_ERR_VALUE(__entry->addr) ? 0 : __entry->addr,
> +		IS_ERR_VALUE(__entry->addr) ? __entry->addr : 0,

I didn't see the IS_ERR_VALUE problem that Vlastimil mentioned get resolved?

I might suggest ...

+++ b/include/linux/err.h
@@ -19,7 +19,8 @@
 
 #ifndef __ASSEMBLY__
 
-#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
+#define __IS_ERR_VALUE(x) ((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
+#define IS_ERR_VALUE(x) unlikely(__IS_ERR_VALUE(x))
 
 static inline void * __must_check ERR_PTR(long error)
 {

and then you can use __IS_ERR_VALUE() which removes the unlikely() problem.
Jaewon Kim March 30, 2020, 4:49 a.m. UTC | #3
On 2020년 03월 30일 01:14, Matthew Wilcox wrote:
> On Fri, Mar 20, 2020 at 02:58:23PM +0900, Jaewon Kim wrote:
>> +	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
>> +		IS_ERR_VALUE(__entry->addr) ? 0 : __entry->addr,
>> +		IS_ERR_VALUE(__entry->addr) ? __entry->addr : 0,
> I didn't see the IS_ERR_VALUE problem that Vlastimil mentioned get resolved?
Sorry I missed the problem. And thank you for your comment and suggestion.

I still do not understand why the unlikely incurs [FAILED TO PARSE] problem on trace-cmd.
Then trace log should not use the unlikely?

I may need to resubmit a new patch set with your suggestion.
Thank you
>
> I might suggest ...
>
> +++ b/include/linux/err.h
> @@ -19,7 +19,8 @@
>  
>  #ifndef __ASSEMBLY__
>  
> -#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
> +#define __IS_ERR_VALUE(x) ((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
> +#define IS_ERR_VALUE(x) unlikely(__IS_ERR_VALUE(x))
>  
>  static inline void * __must_check ERR_PTR(long error)
>  {
>
> and then you can use __IS_ERR_VALUE() which removes the unlikely() problem.
>
>
Vlastimil Babka March 30, 2020, 9:56 a.m. UTC | #4
On 3/29/20 6:14 PM, Matthew Wilcox wrote:
> On Fri, Mar 20, 2020 at 02:58:23PM +0900, Jaewon Kim wrote:
>> +	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
>> +		IS_ERR_VALUE(__entry->addr) ? 0 : __entry->addr,
>> +		IS_ERR_VALUE(__entry->addr) ? __entry->addr : 0,
> 
> I didn't see the IS_ERR_VALUE problem that Vlastimil mentioned get resolved?

Steven is fixing it in trace-cmd:
https://lore.kernel.org/r/20200324200956.821799393@goodmis.org

> I might suggest ...
> 
> +++ b/include/linux/err.h
> @@ -19,7 +19,8 @@
>  
>  #ifndef __ASSEMBLY__
>  
> -#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
> +#define __IS_ERR_VALUE(x) ((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
> +#define IS_ERR_VALUE(x) unlikely(__IS_ERR_VALUE(x))

So this shouldn't be needed, as we are adding a new tracepoint, not "breaking"
an existing one?

>  static inline void * __must_check ERR_PTR(long error)
>  {
> 
> and then you can use __IS_ERR_VALUE() which removes the unlikely() problem.
>
Jaewon Kim March 30, 2020, 9:59 a.m. UTC | #5
On 2020년 03월 30일 18:56, Vlastimil Babka wrote:
> On 3/29/20 6:14 PM, Matthew Wilcox wrote:
>> On Fri, Mar 20, 2020 at 02:58:23PM +0900, Jaewon Kim wrote:
>>> +	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
>>> +		IS_ERR_VALUE(__entry->addr) ? 0 : __entry->addr,
>>> +		IS_ERR_VALUE(__entry->addr) ? __entry->addr : 0,
>> I didn't see the IS_ERR_VALUE problem that Vlastimil mentioned get resolved?
> Steven is fixing it in trace-cmd:
> https://lore.kernel.org/r/20200324200956.821799393@goodmis.org
Good news for me.
Thank you
>
>> I might suggest ...
>>
>> +++ b/include/linux/err.h
>> @@ -19,7 +19,8 @@
>>  
>>  #ifndef __ASSEMBLY__
>>  
>> -#define IS_ERR_VALUE(x) unlikely((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
>> +#define __IS_ERR_VALUE(x) ((unsigned long)(void *)(x) >= (unsigned long)-MAX_ERRNO)
>> +#define IS_ERR_VALUE(x) unlikely(__IS_ERR_VALUE(x))
> So this shouldn't be needed, as we are adding a new tracepoint, not "breaking"
> an existing one?
>
>>  static inline void * __must_check ERR_PTR(long error)
>>  {
>>
>> and then you can use __IS_ERR_VALUE() which removes the unlikely() problem.
>>
>
>
Kirill A. Shutemov March 30, 2020, 4:33 p.m. UTC | #6
On Sun, Mar 29, 2020 at 09:08:58AM -0700, Matthew Wilcox wrote:
> On Fri, Mar 20, 2020 at 02:58:23PM +0900, Jaewon Kim wrote:
> > +	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
> 
> Shouldn't addr be printed as 0x%lx?

%#lx should do the trick.
diff mbox series

Patch

diff --git a/include/trace/events/mmap.h b/include/trace/events/mmap.h
new file mode 100644
index 000000000000..986a41b6cfa9
--- /dev/null
+++ b/include/trace/events/mmap.h
@@ -0,0 +1,48 @@ 
+/* SPDX-License-Identifier: GPL-2.0 */
+#undef TRACE_SYSTEM
+#define TRACE_SYSTEM mmap
+
+#if !defined(_TRACE_MMAP_H) || defined(TRACE_HEADER_MULTI_READ)
+#define _TRACE_MMAP_H
+
+#include <linux/tracepoint.h>
+
+TRACE_EVENT(vm_unmapped_area,
+
+	TP_PROTO(unsigned long addr, struct vm_unmapped_area_info *info),
+
+	TP_ARGS(addr, info),
+
+	TP_STRUCT__entry(
+		__field(unsigned long,	addr)
+		__field(unsigned long,	total_vm)
+		__field(unsigned long,	flags)
+		__field(unsigned long,	length)
+		__field(unsigned long,	low_limit)
+		__field(unsigned long,	high_limit)
+		__field(unsigned long,	align_mask)
+		__field(unsigned long,	align_offset)
+	),
+
+	TP_fast_assign(
+		__entry->addr = addr;
+		__entry->total_vm = current->mm->total_vm;
+		__entry->flags = info->flags;
+		__entry->length = info->length;
+		__entry->low_limit = info->low_limit;
+		__entry->high_limit = info->high_limit;
+		__entry->align_mask = info->align_mask;
+		__entry->align_offset = info->align_offset;
+	),
+
+	TP_printk("addr=%lx err=%ld total_vm=0x%lx flags=0x%lx len=0x%lx lo=0x%lx hi=0x%lx mask=0x%lx ofs=0x%lx\n",
+		IS_ERR_VALUE(__entry->addr) ? 0 : __entry->addr,
+		IS_ERR_VALUE(__entry->addr) ? __entry->addr : 0,
+		__entry->total_vm, __entry->flags, __entry->length,
+		__entry->low_limit, __entry->high_limit, __entry->align_mask,
+		__entry->align_offset)
+);
+#endif
+
+/* This part must be outside protection */
+#include <trace/define_trace.h>
diff --git a/mm/mmap.c b/mm/mmap.c
index ba990c20ecc2..94ae18398c59 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -53,6 +53,9 @@ 
 #include <asm/tlb.h>
 #include <asm/mmu_context.h>
 
+#define CREATE_TRACE_POINTS
+#include <trace/events/mmap.h>
+
 #include "internal.h"
 
 #ifndef arch_mmap_check
@@ -2061,10 +2064,15 @@  static unsigned long unmapped_area_topdown(struct vm_unmapped_area_info *info)
  */
 unsigned long vm_unmapped_area(struct vm_unmapped_area_info *info)
 {
+	unsigned long addr;
+
 	if (info->flags & VM_UNMAPPED_AREA_TOPDOWN)
-		return unmapped_area_topdown(info);
+		addr = unmapped_area_topdown(info);
 	else
-		return unmapped_area(info);
+		addr = unmapped_area(info);
+
+	trace_vm_unmapped_area(addr, info);
+	return addr;
 }
 
 #ifndef arch_get_mmap_end