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[213.175.37.10]) by smtp.gmail.com with ESMTPSA id f7sm1720014wmc.26.2019.05.14.06.17.00 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Tue, 14 May 2019 06:17:00 -0700 (PDT) From: Oleksandr Natalenko To: linux-kernel@vger.kernel.org Cc: Kirill Tkhai , Vlastimil Babka , Michal Hocko , Matthew Wilcox , Pavel Tatashin , Timofey Titovets , Aaron Tomlin , Grzegorz Halat , linux-mm@kvack.org Subject: [PATCH RFC v2 3/4] mm/ksm: introduce force_madvise knob Date: Tue, 14 May 2019 15:16:53 +0200 Message-Id: <20190514131654.25463-4-oleksandr@redhat.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190514131654.25463-1-oleksandr@redhat.com> References: <20190514131654.25463-1-oleksandr@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 --- 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, -- 2.21.0