On Tue 2019-05-14 15:16 +0200, Oleksandr Natalenko wrote: > Present a new sysfs knob to mark task's anonymous memory as mergeable. > > To force merging task's VMAs, its PID is echoed in a write-only file: > > # echo PID > /sys/kernel/mm/ksm/force_madvise > > Force unmerging is done similarly, but with "minus" sign: > > # echo -PID > /sys/kernel/mm/ksm/force_madvise > > "0" or "-0" can be used to control the current task. > > To achieve this, previously introduced ksm_enter()/ksm_leave() helpers > are used in the "store" handler. > > Signed-off-by: Oleksandr Natalenko <[email protected]> > --- > mm/ksm.c | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 68 insertions(+) > > diff --git a/mm/ksm.c b/mm/ksm.c > index e9f3901168bb..22c59fb03d3a 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -2879,10 +2879,77 @@ static void wait_while_offlining(void) > > #define KSM_ATTR_RO(_name) \ > static struct kobj_attribute _name##_attr = __ATTR_RO(_name) > +#define KSM_ATTR_WO(_name) \ > + static struct kobj_attribute _name##_attr = __ATTR_WO(_name) > #define KSM_ATTR(_name) \ > static struct kobj_attribute _name##_attr = \ > __ATTR(_name, 0644, _name##_show, _name##_store) > > +static ssize_t force_madvise_store(struct kobject *kobj, > + struct kobj_attribute *attr, > + const char *buf, size_t count) > +{ > + int err; > + pid_t pid; > + bool merge = true; > + struct task_struct *tsk; > + struct mm_struct *mm; > + struct vm_area_struct *vma; > + > + err = kstrtoint(buf, 10, &pid); > + if (err) > + return -EINVAL; > + > + if (pid < 0) { > + pid = abs(pid); > + merge = false; > + } > + > + if (!pid && *buf == '-') > + merge = false; > + > + rcu_read_lock(); > + if (pid) { > + tsk = find_task_by_vpid(pid); > + if (!tsk) { > + err = -ESRCH; > + rcu_read_unlock(); > + goto out; > + } > + } else { > + tsk = current; > + } > + > + tsk = tsk->group_leader; > + > + get_task_struct(tsk); > + rcu_read_unlock(); > + > + mm = get_task_mm(tsk); > + if (!mm) { > + err = -EINVAL; > + goto out_put_task_struct; > + } > + down_write(&mm->mmap_sem); > + vma = mm->mmap; > + while (vma) { > + if (merge) > + ksm_enter(vma->vm_mm, vma, &vma->vm_flags); > + else > + ksm_leave(vma, vma->vm_start, vma->vm_end, > &vma->vm_flags); > + vma = vma->vm_next; > + } > + up_write(&mm->mmap_sem); > + mmput(mm); > + > +out_put_task_struct: > + put_task_struct(tsk); > + > +out: > + return err ? err : count; > +} > +KSM_ATTR_WO(force_madvise); > + > static ssize_t sleep_millisecs_show(struct kobject *kobj, > struct kobj_attribute *attr, char *buf) > { > @@ -3185,6 +3252,7 @@ static ssize_t full_scans_show(struct kobject *kobj, > KSM_ATTR_RO(full_scans); > > static struct attribute *ksm_attrs[] = { > + &force_madvise_attr.attr, > &sleep_millisecs_attr.attr, > &pages_to_scan_attr.attr, > &run_attr.attr,
Looks fine to me. Reviewed-by: Aaron Tomlin <[email protected]> -- Aaron Tomlin
