* [PATCH] mm/vmstat: fix divide error at __fragmentation_index
@ 2017-08-03 7:59 ` Wen Yang
0 siblings, 0 replies; 7+ messages in thread
From: Wen Yang @ 2017-08-03 7:59 UTC (permalink / raw)
To: linux-mm
Cc: akpm, mhocko, vbabka, kirill.shutemov, hannes, linux-kernel,
wen.yang99, jiang.biao2
From: Jiang Biao <jiang.biao2@zte.com.cn>
When order is -1 or too big, *1UL << order* will be 0, which will
cause divide error like this,
divide error: 0000 [#1] SMP
Call Trace:
[<ffffffff81168423>] compaction_suitable+0x63/0xc0
[<ffffffff81168a75>] compact_zone+0x35/0x950
[<ffffffff811745b5>] ? free_percpu+0xb5/0x140
[<ffffffff81092b23>] ? schedule_on_each_cpu+0x133/0x160
[<ffffffff8116949c>] compact_node+0x10c/0x120
[<ffffffff8116953c>] sysctl_compaction_handler+0x5c/0x90
[<ffffffff811fa517>] proc_sys_call_handler+0x97/0xd0
[<ffffffff811fa564>] proc_sys_write+0x14/0x20
[<ffffffff81187368>] vfs_write+0xb8/0x1a0
[<ffffffff81187c61>] sys_write+0x51/0x90
[<ffffffff8100b052>] system_call_fastpath+0x16/0x1b
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
---
mm/vmstat.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76f7367..2f9d012 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
{
unsigned long requested = 1UL << order;
+ if (!requested)
+ return 0;
+
if (!info->free_blocks_total)
return 0;
--
2.7.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH] mm/vmstat: fix divide error at __fragmentation_index
@ 2017-08-03 7:59 ` Wen Yang
0 siblings, 0 replies; 7+ messages in thread
From: Wen Yang @ 2017-08-03 7:59 UTC (permalink / raw)
To: linux-mm
Cc: akpm, mhocko, vbabka, kirill.shutemov, hannes, linux-kernel,
wen.yang99, jiang.biao2
From: Jiang Biao <jiang.biao2@zte.com.cn>
When order is -1 or too big, *1UL << order* will be 0, which will
cause divide error like this,
divide error: 0000 [#1] SMP
Call Trace:
[<ffffffff81168423>] compaction_suitable+0x63/0xc0
[<ffffffff81168a75>] compact_zone+0x35/0x950
[<ffffffff811745b5>] ? free_percpu+0xb5/0x140
[<ffffffff81092b23>] ? schedule_on_each_cpu+0x133/0x160
[<ffffffff8116949c>] compact_node+0x10c/0x120
[<ffffffff8116953c>] sysctl_compaction_handler+0x5c/0x90
[<ffffffff811fa517>] proc_sys_call_handler+0x97/0xd0
[<ffffffff811fa564>] proc_sys_write+0x14/0x20
[<ffffffff81187368>] vfs_write+0xb8/0x1a0
[<ffffffff81187c61>] sys_write+0x51/0x90
[<ffffffff8100b052>] system_call_fastpath+0x16/0x1b
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
---
mm/vmstat.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76f7367..2f9d012 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
{
unsigned long requested = 1UL << order;
+ if (!requested)
+ return 0;
+
if (!info->free_blocks_total)
return 0;
--
2.7.4
--
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^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] mm/vmstat: fix divide error at __fragmentation_index
2017-08-03 7:59 ` Wen Yang
@ 2017-08-03 8:09 ` Vlastimil Babka
-1 siblings, 0 replies; 7+ messages in thread
From: Vlastimil Babka @ 2017-08-03 8:09 UTC (permalink / raw)
To: Wen Yang, linux-mm
Cc: akpm, mhocko, kirill.shutemov, hannes, linux-kernel, jiang.biao2
Hi,
On 08/03/2017 09:59 AM, Wen Yang wrote:
> From: Jiang Biao <jiang.biao2@zte.com.cn>
>
> When order is -1 or too big, *1UL << order* will be 0, which will
> cause divide error like this,
>
> divide error: 0000 [#1] SMP
> Call Trace:
> [<ffffffff81168423>] compaction_suitable+0x63/0xc0
> [<ffffffff81168a75>] compact_zone+0x35/0x950
> [<ffffffff811745b5>] ? free_percpu+0xb5/0x140
> [<ffffffff81092b23>] ? schedule_on_each_cpu+0x133/0x160
> [<ffffffff8116949c>] compact_node+0x10c/0x120
> [<ffffffff8116953c>] sysctl_compaction_handler+0x5c/0x90
> [<ffffffff811fa517>] proc_sys_call_handler+0x97/0xd0
> [<ffffffff811fa564>] proc_sys_write+0x14/0x20
> [<ffffffff81187368>] vfs_write+0xb8/0x1a0
> [<ffffffff81187c61>] sys_write+0x51/0x90
> [<ffffffff8100b052>] system_call_fastpath+0x16/0x1b
The trace seems to be from an old and non-mainline kernel, as it's the
same as you reported here:
https://bugzilla.kernel.org/show_bug.cgi?id=196555
In current mainline it seems to me that all callers of
__fragmentation_index() will only do so with a valid order.
I wouldn't mind making a non-hotpath code more robust, but probably in a
more obvious and self-reporting/documented way e.g. something like
if (WARN_ON_ONCE(order >= MAX_ORDER))
return 0;
> Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
> Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
> ---
> mm/vmstat.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 76f7367..2f9d012 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
> {
> unsigned long requested = 1UL << order;
>
> + if (!requested)
> + return 0;
Seems the indentation is broken here (spaces vs tabs).
Thanks,
Vlastimil
> +
> if (!info->free_blocks_total)
> return 0;
>
>
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [PATCH] mm/vmstat: fix divide error at __fragmentation_index
@ 2017-08-03 8:09 ` Vlastimil Babka
0 siblings, 0 replies; 7+ messages in thread
From: Vlastimil Babka @ 2017-08-03 8:09 UTC (permalink / raw)
To: Wen Yang, linux-mm
Cc: akpm, mhocko, kirill.shutemov, hannes, linux-kernel, jiang.biao2
Hi,
On 08/03/2017 09:59 AM, Wen Yang wrote:
> From: Jiang Biao <jiang.biao2@zte.com.cn>
>
> When order is -1 or too big, *1UL << order* will be 0, which will
> cause divide error like this,
>
> divide error: 0000 [#1] SMP
> Call Trace:
> [<ffffffff81168423>] compaction_suitable+0x63/0xc0
> [<ffffffff81168a75>] compact_zone+0x35/0x950
> [<ffffffff811745b5>] ? free_percpu+0xb5/0x140
> [<ffffffff81092b23>] ? schedule_on_each_cpu+0x133/0x160
> [<ffffffff8116949c>] compact_node+0x10c/0x120
> [<ffffffff8116953c>] sysctl_compaction_handler+0x5c/0x90
> [<ffffffff811fa517>] proc_sys_call_handler+0x97/0xd0
> [<ffffffff811fa564>] proc_sys_write+0x14/0x20
> [<ffffffff81187368>] vfs_write+0xb8/0x1a0
> [<ffffffff81187c61>] sys_write+0x51/0x90
> [<ffffffff8100b052>] system_call_fastpath+0x16/0x1b
The trace seems to be from an old and non-mainline kernel, as it's the
same as you reported here:
https://bugzilla.kernel.org/show_bug.cgi?id=196555
In current mainline it seems to me that all callers of
__fragmentation_index() will only do so with a valid order.
I wouldn't mind making a non-hotpath code more robust, but probably in a
more obvious and self-reporting/documented way e.g. something like
if (WARN_ON_ONCE(order >= MAX_ORDER))
return 0;
> Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
> Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
> ---
> mm/vmstat.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/mm/vmstat.c b/mm/vmstat.c
> index 76f7367..2f9d012 100644
> --- a/mm/vmstat.c
> +++ b/mm/vmstat.c
> @@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
> {
> unsigned long requested = 1UL << order;
>
> + if (!requested)
> + return 0;
Seems the indentation is broken here (spaces vs tabs).
Thanks,
Vlastimil
> +
> if (!info->free_blocks_total)
> return 0;
>
>
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
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^ permalink raw reply [flat|nested] 7+ messages in thread
* [PATCH] mm/vmstat: fix divide error at __fragmentation_index
@ 2017-08-03 9:12 ` Wen Yang
0 siblings, 0 replies; 7+ messages in thread
From: Wen Yang @ 2017-08-03 9:12 UTC (permalink / raw)
To: linux-mm
Cc: akpm, mhocko, vbabka, kirill.shutemov, hannes, linux-kernel,
wen.yang99, jiang.biao2
When order is -1 or too big, *1UL << order* will be 0, which will
cause divide error. Although it seems that all callers of
__fragmentation_index() will only do so with a valid order, the
patch can make it more robust.
Sugguested-by: VlastimilBabka <vbabka@suse.cz>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
---
mm/vmstat.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76f7367..6f0f1ae 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
{
unsigned long requested = 1UL << order;
+ if (WARN_ON_ONCE(order >= MAX_ORDER))
+ return 0;
+
if (!info->free_blocks_total)
return 0;
--
2.7.4
^ permalink raw reply related [flat|nested] 7+ messages in thread
* [PATCH] mm/vmstat: fix divide error at __fragmentation_index
@ 2017-08-03 9:12 ` Wen Yang
0 siblings, 0 replies; 7+ messages in thread
From: Wen Yang @ 2017-08-03 9:12 UTC (permalink / raw)
To: linux-mm
Cc: akpm, mhocko, vbabka, kirill.shutemov, hannes, linux-kernel,
wen.yang99, jiang.biao2
When order is -1 or too big, *1UL << order* will be 0, which will
cause divide error. Although it seems that all callers of
__fragmentation_index() will only do so with a valid order, the
patch can make it more robust.
Sugguested-by: VlastimilBabka <vbabka@suse.cz>
Signed-off-by: Wen Yang <wen.yang99@zte.com.cn>
Reviewed-by: Jiang Biao <jiang.biao2@zte.com.cn>
---
mm/vmstat.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 76f7367..6f0f1ae 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
{
unsigned long requested = 1UL << order;
+ if (WARN_ON_ONCE(order >= MAX_ORDER))
+ return 0;
+
if (!info->free_blocks_total)
return 0;
--
2.7.4
--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: [PATCH] mm/vmstat: fix divide error at __fragmentation_index
@ 2017-08-03 8:46 jiang.biao2
0 siblings, 0 replies; 7+ messages in thread
From: jiang.biao2 @ 2017-08-03 8:46 UTC (permalink / raw)
To: vbabka
Cc: wen.yang99, linux-mm, akpm, mhocko, kirill.shutemov, hannes,
linux-kernel
[-- Attachment #1.1.1: Type: text/plain, Size: 1213 bytes --]
> > On 08/03/2017 09:59 AM, Wen Yang wrote:
> > From: Jiang Biao <jiang.biao2@zte.com.cn>
> >
> > When order is -1 or too big, *1UL << order* will be 0, which will
> > cause divide error like this,
> >
> > divide error: 0000 [#1] SMP
> > Call Trace:
>> [<ffffffff81168423>] compaction_suitable+0x63/0xc0
>> ...
> The trace seems to be from an old and non-mainline kernel, as it's the
> same as you reported here:
>
> https://bugzilla.kernel.org/show_bug.cgi?id=196555
>
> In current mainline it seems to me that all callers of
> __fragmentation_index() will only do so with a valid order.
>
> I wouldn't mind making a non-hotpath code more robust, but probably in a
> more obvious and self-reporting/documented way e.g. something like
>
> if (WARN_ON_ONCE(order >= MAX_ORDER))
> return 0
>
yes, I noticed that, I'll send a new patch for that.
> > @@ -870,6 +870,9 @@ static int __fragmentation_index(unsigned int order, struct contig_page_info *in
> > {
> > unsigned long requested = 1UL << order
> >
> > + if (!requested)
> > + return 0
>
> Seems the indentation is broken here (spaces vs tabs).
I'll fix that.
[-- Attachment #1.1.2: Type: text/html , Size: 2542 bytes --]
^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2017-08-03 9:00 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-08-03 7:59 [PATCH] mm/vmstat: fix divide error at __fragmentation_index Wen Yang
2017-08-03 7:59 ` Wen Yang
2017-08-03 8:09 ` Vlastimil Babka
2017-08-03 8:09 ` Vlastimil Babka
2017-08-03 8:46 jiang.biao2
2017-08-03 9:12 Wen Yang
2017-08-03 9:12 ` Wen Yang
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