* bug#27587: 25.1; in the dynamic modules api, env->free_global_ref doesn't free anything
@ 2017-07-05 12:43 Valentin Gatien-Baron
2017-07-09 22:17 ` Philipp Stephani
0 siblings, 1 reply; 3+ messages in thread
From: Valentin Gatien-Baron @ 2017-07-05 12:43 UTC (permalink / raw)
To: 27587
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The following dynamic module takes unbounded memory:
/* gcc -I . -g -ggdb -fPIC foo.c -shared -o foo.so && echo running && emacs
-Q -L . -batch -l foo */
#include <emacs-module.h>
int plugin_is_GPL_compatible;
int emacs_module_init(struct emacs_runtime *ert) {
emacs_env *env = ert->get_environment(ert);
while (1) {
int i;
for (i = 0; i < 10000; i++) {
emacs_value v = env->make_string(env, "asdads", 3);
env->free_global_ref(env, env->make_global_ref(env, v));
}
env->funcall(env, env->intern(env, "garbage-collect"), 0, NULL);
}
}
This is because env->make_global_ref/env->free_global_ref leak memory.
env->free_global_ref fails to remove values from the hash table of
refcounts. The following patch makes the program above run in constant
space.
--- src/emacs-module.c 2017-06-30 16:00:36.776301646 -0400
+++ src/emacs-module.c 2017-06-30 16:05:01.660120043 -0400
@@ -308,7 +308,7 @@
set_hash_value_slot (h, i, value);
}
else
- hash_remove_from_table (h, value);
+ hash_remove_from_table (h, obj);
}
}
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^ permalink raw reply [flat|nested] 3+ messages in thread
* bug#27587: 25.1; in the dynamic modules api, env->free_global_ref doesn't free anything
2017-07-05 12:43 bug#27587: 25.1; in the dynamic modules api, env->free_global_ref doesn't free anything Valentin Gatien-Baron
@ 2017-07-09 22:17 ` Philipp Stephani
2017-07-10 15:10 ` Valentin Gatien-Baron
0 siblings, 1 reply; 3+ messages in thread
From: Philipp Stephani @ 2017-07-09 22:17 UTC (permalink / raw)
To: Valentin Gatien-Baron, 27587-done
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Valentin Gatien-Baron <vgatien-baron@janestreet.com> schrieb am Mi., 5.
Juli 2017 um 17:07 Uhr:
> The following dynamic module takes unbounded memory:
>
> /* gcc -I . -g -ggdb -fPIC foo.c -shared -o foo.so && echo running &&
> emacs -Q -L . -batch -l foo */
> #include <emacs-module.h>
>
> int plugin_is_GPL_compatible;
>
> int emacs_module_init(struct emacs_runtime *ert) {
> emacs_env *env = ert->get_environment(ert);
> while (1) {
> int i;
> for (i = 0; i < 10000; i++) {
> emacs_value v = env->make_string(env, "asdads", 3);
> env->free_global_ref(env, env->make_global_ref(env, v));
> }
> env->funcall(env, env->intern(env, "garbage-collect"), 0, NULL);
> }
> }
>
>
> This is because env->make_global_ref/env->free_global_ref leak memory.
> env->free_global_ref fails to remove values from the hash table of
> refcounts. The following patch makes the program above run in constant
> space.
>
>
> --- src/emacs-module.c 2017-06-30 16:00:36.776301646 -0400
> +++ src/emacs-module.c 2017-06-30 16:05:01.660120043 -0400
> @@ -308,7 +308,7 @@
> set_hash_value_slot (h, i, value);
> }
> else
> - hash_remove_from_table (h, value);
> + hash_remove_from_table (h, obj);
> }
> }
>
>
Good catch, installed as 22af69906cca871fdb893e06d6f10dbbab4518e6.
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* bug#27587: 25.1; in the dynamic modules api, env->free_global_ref doesn't free anything
2017-07-09 22:17 ` Philipp Stephani
@ 2017-07-10 15:10 ` Valentin Gatien-Baron
0 siblings, 0 replies; 3+ messages in thread
From: Valentin Gatien-Baron @ 2017-07-10 15:10 UTC (permalink / raw)
To: Philipp Stephani; +Cc: 27587-done
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Thanks! By the way, the assert that refcount == 0 you added as a further
commit wouldn't have triggered, as the refcount in the hash table would
stay at 1 after the call to free_global_ref.
On Sun, Jul 9, 2017 at 6:17 PM, Philipp Stephani <p.stephani2@gmail.com>
wrote:
>
>
> Valentin Gatien-Baron <vgatien-baron@janestreet.com> schrieb am Mi., 5.
> Juli 2017 um 17:07 Uhr:
>
>> The following dynamic module takes unbounded memory:
>>
>> /* gcc -I . -g -ggdb -fPIC foo.c -shared -o foo.so && echo running &&
>> emacs -Q -L . -batch -l foo */
>> #include <emacs-module.h>
>>
>> int plugin_is_GPL_compatible;
>>
>> int emacs_module_init(struct emacs_runtime *ert) {
>> emacs_env *env = ert->get_environment(ert);
>> while (1) {
>> int i;
>> for (i = 0; i < 10000; i++) {
>> emacs_value v = env->make_string(env, "asdads", 3);
>> env->free_global_ref(env, env->make_global_ref(env, v));
>> }
>> env->funcall(env, env->intern(env, "garbage-collect"), 0, NULL);
>> }
>> }
>>
>>
>> This is because env->make_global_ref/env->free_global_ref leak memory.
>> env->free_global_ref fails to remove values from the hash table of
>> refcounts. The following patch makes the program above run in constant
>> space.
>>
>>
>> --- src/emacs-module.c 2017-06-30 16:00:36.776301646 -0400
>> +++ src/emacs-module.c 2017-06-30 16:05:01.660120043 -0400
>> @@ -308,7 +308,7 @@
>> set_hash_value_slot (h, i, value);
>> }
>> else
>> - hash_remove_from_table (h, value);
>> + hash_remove_from_table (h, obj);
>> }
>> }
>>
>>
> Good catch, installed as 22af69906cca871fdb893e06d6f10dbbab4518e6.
>
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2017-07-05 12:43 bug#27587: 25.1; in the dynamic modules api, env->free_global_ref doesn't free anything Valentin Gatien-Baron
2017-07-09 22:17 ` Philipp Stephani
2017-07-10 15:10 ` Valentin Gatien-Baron
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