2021-03-24 19:52:31

by Dmitry Osipenko

[permalink] [raw]
Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count

24.03.2021 22:43, Dmitry Osipenko пишет:
> 24.03.2021 22:20, Minchan Kim пишет:
>> static int __init cma_sysfs_init(void)
>> {
>> - int i = 0;
>> + struct kobject *cma_kobj_root;
>> + struct cma_kobject *cma_kobj;
>> struct cma *cma;
>> + unsigned int i;
>
>> while (--i >= 0) {
>
> Do you realize that this doesn't work anymore?
>
>> cma = &cma_areas[i];
>> - kobject_put(&cma->stat->kobj);
>> - }
>>
>> - kfree(cma_stats);
>> - kobject_put(cma_kobj);
>> + kobject_put(&cma->cma_kobj->kobj);
>> + kfree(cma->cma_kobj);
>
> Freeing a null pointer?
>
>> + cma->cma_kobj = NULL;
>> + }
>> + kobject_put(cma_kobj_root);
>

Please try to simulate the errors and check that error path is working
properly in the next version.

Alternatively, we could remove the cma_kobj_release entirely, like Greg
suggested previously, and then don't care about cleaning up at all.


2021-03-24 20:00:39

by Minchan Kim

[permalink] [raw]
Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count

On Wed, Mar 24, 2021 at 10:49:58PM +0300, Dmitry Osipenko wrote:
> 24.03.2021 22:43, Dmitry Osipenko пишет:
> > 24.03.2021 22:20, Minchan Kim пишет:
> >> static int __init cma_sysfs_init(void)
> >> {
> >> - int i = 0;
> >> + struct kobject *cma_kobj_root;
> >> + struct cma_kobject *cma_kobj;
> >> struct cma *cma;
> >> + unsigned int i;
> >
> >> while (--i >= 0) {
> >
> > Do you realize that this doesn't work anymore?
> >
> >> cma = &cma_areas[i];
> >> - kobject_put(&cma->stat->kobj);
> >> - }
> >>
> >> - kfree(cma_stats);
> >> - kobject_put(cma_kobj);
> >> + kobject_put(&cma->cma_kobj->kobj);
> >> + kfree(cma->cma_kobj);
> >
> > Freeing a null pointer?
> >
> >> + cma->cma_kobj = NULL;
> >> + }
> >> + kobject_put(cma_kobj_root);
> >
>
> Please try to simulate the errors and check that error path is working
> properly in the next version.
>
> Alternatively, we could remove the cma_kobj_release entirely, like Greg
> suggested previously, and then don't care about cleaning up at all.

Does he suggested it to remove cma_kobj_release?(Initially, I did but
was rejected from Greg)

2021-03-24 20:08:11

by Dmitry Osipenko

[permalink] [raw]
Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count

24.03.2021 22:57, Minchan Kim пишет:
> On Wed, Mar 24, 2021 at 10:49:58PM +0300, Dmitry Osipenko wrote:
>> 24.03.2021 22:43, Dmitry Osipenko пишет:
>>> 24.03.2021 22:20, Minchan Kim пишет:
>>>> static int __init cma_sysfs_init(void)
>>>> {
>>>> - int i = 0;
>>>> + struct kobject *cma_kobj_root;
>>>> + struct cma_kobject *cma_kobj;
>>>> struct cma *cma;
>>>> + unsigned int i;
>>>
>>>> while (--i >= 0) {
>>>
>>> Do you realize that this doesn't work anymore?
>>>
>>>> cma = &cma_areas[i];
>>>> - kobject_put(&cma->stat->kobj);
>>>> - }
>>>>
>>>> - kfree(cma_stats);
>>>> - kobject_put(cma_kobj);
>>>> + kobject_put(&cma->cma_kobj->kobj);
>>>> + kfree(cma->cma_kobj);
>>>
>>> Freeing a null pointer?
>>>
>>>> + cma->cma_kobj = NULL;
>>>> + }
>>>> + kobject_put(cma_kobj_root);
>>>
>>
>> Please try to simulate the errors and check that error path is working
>> properly in the next version.
>>
>> Alternatively, we could remove the cma_kobj_release entirely, like Greg
>> suggested previously, and then don't care about cleaning up at all.
>
> Does he suggested it to remove cma_kobj_release?(Initially, I did but
> was rejected from Greg)
>

Alright, I haven't followed the previous threads fully and only saw the
reply where he suggested to removed it.


2021-03-24 21:01:09

by Minchan Kim

[permalink] [raw]
Subject: Re: [PATCH] mm: cma: fix corruption cma_sysfs_alloc_pages_count

On Wed, Mar 24, 2021 at 11:02:47PM +0300, Dmitry Osipenko wrote:
> 24.03.2021 22:57, Minchan Kim пишет:
> > On Wed, Mar 24, 2021 at 10:49:58PM +0300, Dmitry Osipenko wrote:
> >> 24.03.2021 22:43, Dmitry Osipenko пишет:
> >>> 24.03.2021 22:20, Minchan Kim пишет:
> >>>> static int __init cma_sysfs_init(void)
> >>>> {
> >>>> - int i = 0;
> >>>> + struct kobject *cma_kobj_root;
> >>>> + struct cma_kobject *cma_kobj;
> >>>> struct cma *cma;
> >>>> + unsigned int i;
> >>>
> >>>> while (--i >= 0) {
> >>>
> >>> Do you realize that this doesn't work anymore?
> >>>
> >>>> cma = &cma_areas[i];
> >>>> - kobject_put(&cma->stat->kobj);
> >>>> - }
> >>>>
> >>>> - kfree(cma_stats);
> >>>> - kobject_put(cma_kobj);
> >>>> + kobject_put(&cma->cma_kobj->kobj);
> >>>> + kfree(cma->cma_kobj);
> >>>
> >>> Freeing a null pointer?
> >>>
> >>>> + cma->cma_kobj = NULL;
> >>>> + }
> >>>> + kobject_put(cma_kobj_root);
> >>>
> >>
> >> Please try to simulate the errors and check that error path is working
> >> properly in the next version.
> >>
> >> Alternatively, we could remove the cma_kobj_release entirely, like Greg
> >> suggested previously, and then don't care about cleaning up at all.
> >
> > Does he suggested it to remove cma_kobj_release?(Initially, I did but
> > was rejected from Greg)
> >
>
> Alright, I haven't followed the previous threads fully and only saw the
> reply where he suggested to removed it.

No problem. I just posted it new version. Hopefully, it tastes good
for you. ;-)

Thanks for the review!