On Mon 29-02-16 18:38:45, Oleg Nesterov wrote:
> On 02/29, Michal Hocko wrote:
> >
> > --- a/fs/proc/task_mmu.c
> > +++ b/fs/proc/task_mmu.c
> > @@ -1027,11 +1027,15 @@ static ssize_t clear_refs_write(struct file *file,
> > const char __user *buf,
> > };
> >
> > if (type == CLEAR_REFS_MM_HIWATER_RSS) {
> > + if (down_write_killable(&mm->mmap_sem)) {
> > + put_task_struct(task);
> > + return -EINTR;
> > + }
> > +
> > /*
> > * Writing 5 to /proc/pid/clear_refs resets the peak
> > * resident set size to this mm's current rss value.
> > */
> > - down_write(&mm->mmap_sem);
> > reset_mm_hiwater_rss(mm);
> > up_write(&mm->mmap_sem);
> > goto out_mm;
> > @@ -1043,7 +1047,10 @@ static ssize_t clear_refs_write(struct file *file,
> > const char __user *buf,
> > if (!(vma->vm_flags & VM_SOFTDIRTY))
> > continue;
> > up_read(&mm->mmap_sem);
> > - down_write(&mm->mmap_sem);
> > + if (down_write_killable(&mm->mmap_sem)) {
> > + put_task_struct(task);
> > + return -EINTR;
> > + }
>
> Both lack mmput() afaics. Don't you need "goto out_mm" rather then "return" ?
Of course I need! Thanks for catching that.
> In this case you do not need put_task_struct().
Why not? Both are after get_proc_task which takes a reference to the
task...
I will send an updated patch. Thanks!
--
Michal Hocko
SUSE Labs
