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

[Konstantin Khlebnikov]

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@xxxxxxxxxxxxxx>
> > ---
> >   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;