2023-03-09 03:43:10

by ye.xingchen

Subject: [PATCH V3 2/2] mm: compaction: limit illegal input parameters of compact_memory interface

From: Minghao Chi <[email protected]>

Available only when CONFIG_COMPACTION is set. When 1 is written to
the file, all zones are compacted such that free memory is available
in contiguous blocks where possible.
But echo others-parameter > compact_memory, this function will be
triggered by writing parameters to the interface.

Applied this patch,
sh/$ echo 1.1 > /proc/sys/vm/compact_memory
sh/$ sh: write error: Invalid argument

Link: https://lore.kernel.org/all/[email protected]/
Signed-off-by: Minghao Chi <[email protected]>
Signed-off-by: Ye Xingchen <[email protected]>
---
mm/compaction.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/mm/compaction.c b/mm/compaction.c
index acbda28c11f4..39f4c8a6f843 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -2762,15 +2762,18 @@ int compaction_proactiveness_sysctl_handler(struct ctl_table *table, int write,

return 0;
}
+static int sysctl_compact_memory;

#ifdef CONFIG_SYSCTL
static struct ctl_table vm_compact_memory[] = {
{
.procname = "compact_memory",
- .data = NULL,
+ .data = &sysctl_compact_memory,
.maxlen = sizeof(int),
.mode = 0200,
.proc_handler = sysctl_compaction_handler,
+ .extra1 = SYSCTL_ONE,
+ .extra2 = SYSCTL_ONE,
},
{ }
};
@@ -2782,6 +2785,11 @@ static struct ctl_table vm_compact_memory[] = {
int sysctl_compaction_handler(struct ctl_table *table, int write,
void *buffer, size_t *length, loff_t *ppos)
{
+ int ret;
+
+ ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
+ if (ret)
+ return ret;
if (write)
compact_nodes();

--
2.25.1

2023-03-09 03:56:51

by Luis Chamberlain

Subject: Re: [PATCH V3 2/2] mm: compaction: limit illegal input parameters of compact_memory interface

On Thu, Mar 09, 2023 at 11:42:58AM +0800, [email protected] wrote:
> From: Minghao Chi <[email protected]>
>
> Available only when CONFIG_COMPACTION is set. When 1 is written to
> the file, all zones are compacted such that free memory is available
> in contiguous blocks where possible.
> But echo others-parameter > compact_memory, this function will be
> triggered by writing parameters to the interface.
>
> Applied this patch,
> sh/$ echo 1.1 > /proc/sys/vm/compact_memory
> sh/$ sh: write error: Invalid argument

Didn't echo 2 > /proc/sys/vm/compact_memory used to work too?

Why kill that? Did the docs say only 1 was possible? If not
perhaps the docs need to be updated?

Luis

2023-03-10 01:55:02

by ye xingchen

Subject: Re: [PATCH V3 2/2] mm: compaction: limit illegal input parameters of compact_memory interface

>> From: Minghao Chi <[email protected]>
>>
>> Available only when CONFIG_COMPACTION is set. When 1 is written to
>> the file, all zones are compacted such that free memory is available
>> in contiguous blocks where possible.
>> But echo others-parameter > compact_memory, this function will be
>> triggered by writing parameters to the interface.
>>
>> Applied this patch,
>> sh/$ echo 1.1 > /proc/sys/vm/compact_memory
>> sh/$ sh: write error: Invalid argument
>
>Didn't echo 2 > /proc/sys/vm/compact_memory used to work too?
yes
>
>Why kill that? Did the docs say only 1 was possible? If not
>perhaps the docs need to be updated?
In Documentation/admin-guide/sysctl/vm.rst:109 say: when 1 is written
to the file, all zones are compacted such that free memory is available
in contiguous blocks where possible.
So limit the value of interface compact_memory to 1.

Chi, and Ye