From: Timofey Titovets <nefelim4ag@gmail.com>
To: Aaron Tomlin <atomlin@redhat.com>
Cc: Oleksandr Natalenko <oleksandr@redhat.com>,
Linux Kernel <linux-kernel@vger.kernel.org>,
Kirill Tkhai <ktkhai@virtuozzo.com>,
Vlastimil Babka <vbabka@suse.cz>, Michal Hocko <mhocko@suse.com>,
Matthew Wilcox <willy@infradead.org>,
Pavel Tatashin <pasha.tatashin@soleen.com>,
Grzegorz Halat <ghalat@redhat.com>,
linux-mm@kvack.org
Subject: Re: [PATCH RFC v2 3/4] mm/ksm: introduce force_madvise knob
Date: Wed, 15 May 2019 03:48:50 +0300 [thread overview]
Message-ID: <CAGqmi77dtid9M8fZuWimeiWMw8r9Awu579mo8UsaVGTECwxRwA@mail.gmail.com> (raw)
In-Reply-To: <20190514132249.h233crdsz3b7akys@atomlin.usersys.com>
LGTM
Reviewed-by: Timofey Titovets <nefelim4ag@gmail.com>
вт, 14 мая 2019 г. в 16:22, Aaron Tomlin <atomlin@redhat.com>:
>
> 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 <oleksandr@redhat.com>
> > ---
> > 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 <atomlin@redhat.com>
>
> --
> Aaron Tomlin
--
Have a nice day,
Timofey.
next prev parent reply other threads:[~2019-05-15 0:49 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-14 13:16 [PATCH RFC v2 0/4] mm/ksm: add option to automerge VMAs Oleksandr Natalenko
2019-05-14 13:16 ` [PATCH RFC v2 1/4] mm/ksm: introduce ksm_enter() helper Oleksandr Natalenko
2019-05-14 13:16 ` [PATCH RFC v2 2/4] mm/ksm: introduce ksm_leave() helper Oleksandr Natalenko
2019-05-14 13:16 ` [PATCH RFC v2 3/4] mm/ksm: introduce force_madvise knob Oleksandr Natalenko
2019-05-14 13:22 ` Aaron Tomlin
2019-05-15 0:48 ` Timofey Titovets [this message]
2019-05-14 13:16 ` [PATCH RFC v2 4/4] mm/ksm: add force merging/unmerging documentation Oleksandr Natalenko
2019-05-15 0:53 ` Timofey Titovets
2019-05-15 6:26 ` Oleksandr Natalenko
2019-05-14 14:41 ` [PATCH RFC v2 0/4] mm/ksm: add option to automerge VMAs Michal Hocko
2019-05-14 14:51 ` Michal Hocko
2019-05-15 6:25 ` Oleksandr Natalenko
2019-05-15 6:53 ` Michal Hocko
2019-05-15 7:37 ` Oleksandr Natalenko
2019-05-15 8:33 ` Michal Hocko
2019-05-15 8:51 ` Oleksandr Natalenko
2019-05-15 14:24 ` Michal Hocko
2019-05-15 14:51 ` Michal Hocko
2019-05-15 15:15 ` Greg KH
2019-05-16 7:47 ` Michal Hocko
2019-05-16 7:53 ` Greg KH
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