2023-07-16 01:47:05

by Chao Yu

Subject: [PATCH 1/2] mm/damon/dbgfs: reduce stack usage in str_to_schemes()

struct damos_quota quota caused the stack usage of str_to_schemes() to
grow beyond the warning limit on 32-bit architectures w/ gcc.

mm/damon/dbgfs.c: In function ‘str_to_schemes’:
mm/damon/dbgfs.c:292:1: warning: the frame size of 1496 bytes is larger than 1024 bytes [-Wframe-larger-than=]

Allocating dynamic memory in str_to_schemes() to fix this issue.

Signed-off-by: Chao Yu <[email protected]>
---
mm/damon/dbgfs.c | 22 ++++++++++++++++------
1 file changed, 16 insertions(+), 6 deletions(-)

diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
index 124f0f8c97b7..78acc7366895 100644
--- a/mm/damon/dbgfs.c
+++ b/mm/damon/dbgfs.c
@@ -237,18 +237,26 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
int pos = 0, parsed, ret;
unsigned int action_input;
enum damos_action action;
+ struct damos_quota *quota;

schemes = kmalloc_array(max_nr_schemes, sizeof(scheme),
GFP_KERNEL);
if (!schemes)
return NULL;

+ quota = kmalloc(sizeof(struct damos_quota), GFP_KERNEL);
+ if (!quota) {
+ kfree(schemes);
+ return NULL;
+ }
+
*nr_schemes = 0;
while (pos < len && *nr_schemes < max_nr_schemes) {
struct damos_access_pattern pattern = {};
- struct damos_quota quota = {};
struct damos_watermarks wmarks;

+ memset(quota, 0, sizeof(struct damos_quota));
+
ret = sscanf(&str[pos],
"%lu %lu %u %u %u %u %u %lu %lu %lu %u %u %u %u %lu %lu %lu %lu%n",
&pattern.min_sz_region, &pattern.max_sz_region,
@@ -256,10 +264,10 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
&pattern.max_nr_accesses,
&pattern.min_age_region,
&pattern.max_age_region,
- &action_input, &quota.ms,
- &quota.sz, &quota.reset_interval,
- &quota.weight_sz, &quota.weight_nr_accesses,
- &quota.weight_age, &wmarks.metric,
+ &action_input, &quota->ms,
+ &quota->sz, &quota->reset_interval,
+ &quota->weight_sz, &quota->weight_nr_accesses,
+ &quota->weight_age, &wmarks.metric,
&wmarks.interval, &wmarks.high, &wmarks.mid,
&wmarks.low, &parsed);
if (ret != 18)
@@ -278,15 +286,17 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
goto fail;

pos += parsed;
- scheme = damon_new_scheme(&pattern, action, &quota, &wmarks);
+ scheme = damon_new_scheme(&pattern, action, quota, &wmarks);
if (!scheme)
goto fail;

schemes[*nr_schemes] = scheme;
*nr_schemes += 1;
}
+ kfree(quota);
return schemes;
fail:
+ kfree(quota);
free_schemes_arr(schemes, *nr_schemes);
return NULL;
}
--
2.40.1

2023-07-17 03:53:58

by Chao Yu

Subject: Re: [PATCH 1/2] mm/damon/dbgfs: reduce stack usage in str_to_schemes()

Hi all,

It warned because my config is wrong, sorry for the mistake, please
ignore the patchset. :-P

Thanks,

On 2023/7/16 9:09, Chao Yu wrote:
> struct damos_quota quota caused the stack usage of str_to_schemes() to
> grow beyond the warning limit on 32-bit architectures w/ gcc.
>
> mm/damon/dbgfs.c: In function ‘str_to_schemes’:
> mm/damon/dbgfs.c:292:1: warning: the frame size of 1496 bytes is larger than 1024 bytes [-Wframe-larger-than=]
>
> Allocating dynamic memory in str_to_schemes() to fix this issue.
>
> Signed-off-by: Chao Yu <[email protected]>
> ---
> mm/damon/dbgfs.c | 22 ++++++++++++++++------
> 1 file changed, 16 insertions(+), 6 deletions(-)
>
> diff --git a/mm/damon/dbgfs.c b/mm/damon/dbgfs.c
> index 124f0f8c97b7..78acc7366895 100644
> --- a/mm/damon/dbgfs.c
> +++ b/mm/damon/dbgfs.c
> @@ -237,18 +237,26 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
> int pos = 0, parsed, ret;
> unsigned int action_input;
> enum damos_action action;
> + struct damos_quota *quota;
>
> schemes = kmalloc_array(max_nr_schemes, sizeof(scheme),
> GFP_KERNEL);
> if (!schemes)
> return NULL;
>
> + quota = kmalloc(sizeof(struct damos_quota), GFP_KERNEL);
> + if (!quota) {
> + kfree(schemes);
> + return NULL;
> + }
> +
> *nr_schemes = 0;
> while (pos < len && *nr_schemes < max_nr_schemes) {
> struct damos_access_pattern pattern = {};
> - struct damos_quota quota = {};
> struct damos_watermarks wmarks;
>
> + memset(quota, 0, sizeof(struct damos_quota));
> +
> ret = sscanf(&str[pos],
> "%lu %lu %u %u %u %u %u %lu %lu %lu %u %u %u %u %lu %lu %lu %lu%n",
> &pattern.min_sz_region, &pattern.max_sz_region,
> @@ -256,10 +264,10 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
> &pattern.max_nr_accesses,
> &pattern.min_age_region,
> &pattern.max_age_region,
> - &action_input, &quota.ms,
> - &quota.sz, &quota.reset_interval,
> - &quota.weight_sz, &quota.weight_nr_accesses,
> - &quota.weight_age, &wmarks.metric,
> + &action_input, &quota->ms,
> + &quota->sz, &quota->reset_interval,
> + &quota->weight_sz, &quota->weight_nr_accesses,
> + &quota->weight_age, &wmarks.metric,
> &wmarks.interval, &wmarks.high, &wmarks.mid,
> &wmarks.low, &parsed);
> if (ret != 18)
> @@ -278,15 +286,17 @@ static struct damos **str_to_schemes(const char *str, ssize_t len,
> goto fail;
>
> pos += parsed;
> - scheme = damon_new_scheme(&pattern, action, &quota, &wmarks);
> + scheme = damon_new_scheme(&pattern, action, quota, &wmarks);
> if (!scheme)
> goto fail;
>
> schemes[*nr_schemes] = scheme;
> *nr_schemes += 1;
> }
> + kfree(quota);
> return schemes;
> fail:
> + kfree(quota);
> free_schemes_arr(schemes, *nr_schemes);
> return NULL;
> }

2023-07-17 19:27:53

by SeongJae Park

Subject: Re: [PATCH 1/2] mm/damon/dbgfs: reduce stack usage in str_to_schemes()

Hi Chao,

On Mon, 17 Jul 2023 11:41:01 +0800 Chao Yu <[email protected]> wrote:

> Hi all,
>
> It warned because my config is wrong, sorry for the mistake, please
> ignore the patchset. :-P

No problem at all, appreciate for taking a look into DAMON :)


Thanks,
SJ

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