Re: [PATCH 2/5] proc: use down_read_killable for /proc/pid/smaps_rollup

Konstantin Khlebnikov
2019-06-09T09:07:41Z

On 17.05.2019 15:45, Michal Hocko wrote:
> On Wed 15-05-19 11:41:14, Konstantin Khlebnikov wrote:
>> Ditto.
>
> Proper changelog or simply squash those patches into a single patch if
> you do not feel like copy&paste is fun
>
>>
>> Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
>> ---
>> fs/proc/task_mmu.c | 8 ++++++--
>> 1 file changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
>> index 2bf210229daf..781879a91e3b 100644
>> --- a/fs/proc/task_mmu.c
>> +++ b/fs/proc/task_mmu.c
>> @@ -832,7 +832,10 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
>>
>> memset(&mss, 0, sizeof(mss));
>>
>> - down_read(&mm->mmap_sem);
>> + ret = down_read_killable(&mm->mmap_sem);
>> + if (ret)
>> + goto out_put_mm;
>
> Why not ret = -EINTR. The seq_file code seems to be handling all errors
> AFAICS.
>

I've missed your comment. Sorry.

down_read_killable returns 0 for success and exactly -EINTR for failure.

>> +
>> hold_task_mempolicy(priv);
>>
>> for (vma = priv->mm->mmap; vma; vma = vma->vm_next) {
>> @@ -849,8 +852,9 @@ static int show_smaps_rollup(struct seq_file *m, void *v)
>>
>> release_task_mempolicy(priv);
>> up_read(&mm->mmap_sem);
>> - mmput(mm);
>>
>> +out_put_mm:
>> + mmput(mm);
>> out_put_task:
>> put_task_struct(priv->task);
>> priv->task = NULL;
>