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Thu, 7 May 2020 00:43:46 GMT Received: from userv0121.oracle.com (userv0121.oracle.com [156.151.31.72]) by userp3020.oracle.com with ESMTP id 30us7p2n40-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 07 May 2020 00:43:46 +0000 Received: from abhmp0014.oracle.com (abhmp0014.oracle.com [141.146.116.20]) by userv0121.oracle.com (8.14.4/8.13.8) with ESMTP id 0470hhja024556; Thu, 7 May 2020 00:43:43 GMT Received: from ayz-linux.localdomain (/68.7.158.207) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Wed, 06 May 2020 17:43:42 -0700 From: Anthony Yznaga To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: willy@infradead.org, corbet@lwn.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, rppt@linux.ibm.com, akpm@linux-foundation.org, hughd@google.com, ebiederm@xmission.com, masahiroy@kernel.org, ardb@kernel.org, ndesaulniers@google.com, dima@golovin.in, daniel.kiper@oracle.com, nivedita@alum.mit.edu, rafael.j.wysocki@intel.com, dan.j.williams@intel.com, zhenzhong.duan@oracle.com, jroedel@suse.de, bhe@redhat.com, guro@fb.com, Thomas.Lendacky@amd.com, andriy.shevchenko@linux.intel.com, keescook@chromium.org, hannes@cmpxchg.org, minchan@kernel.org, mhocko@kernel.org, ying.huang@intel.com, yang.shi@linux.alibaba.com, gustavo@embeddedor.com, ziqian.lzq@antfin.com, vdavydov.dev@gmail.com, jason.zeng@intel.com, kevin.tian@intel.com, zhiyuan.lv@intel.com, lei.l.li@intel.com, paul.c.lai@intel.com, ashok.raj@intel.com, linux-fsdevel@vger.kernel.org, linux-doc@vger.kernel.org, kexec@lists.infradead.org Subject: [RFC 19/43] mm: PKRAM: allow preserved memory to be freed from userspace Date: Wed, 6 May 2020 17:41:45 -0700 Message-Id: <1588812129-8596-20-git-send-email-anthony.yznaga@oracle.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> References: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9613 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 adultscore=0 suspectscore=2 mlxlogscore=999 malwarescore=0 phishscore=0 mlxscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005070001 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9613 signatures=668687 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 bulkscore=0 mlxscore=0 lowpriorityscore=0 spamscore=0 adultscore=0 clxscore=1015 suspectscore=2 priorityscore=1501 malwarescore=0 mlxlogscore=999 phishscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2005070001 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: To free all space utilized for preserved memory, one can write 0 to /sys/kernel/pkram. This will destroy all PKRAM nodes that are not currently being read or written. Originally-by: Vladimir Davydov Signed-off-by: Anthony Yznaga --- mm/pkram.c | 39 ++++++++++++++++++++++++++++++++++++++- 1 file changed, 38 insertions(+), 1 deletion(-) diff --git a/mm/pkram.c b/mm/pkram.c index 0aaaf9b79682..95e691382721 100644 --- a/mm/pkram.c +++ b/mm/pkram.c @@ -509,6 +509,32 @@ static void pkram_truncate_node(struct pkram_node *node) node->obj_pfn = 0; } +/* + * Free all nodes that are not under operation. + */ +static void pkram_truncate(void) +{ + struct page *page, *tmp; + struct pkram_node *node; + LIST_HEAD(dispose); + + mutex_lock(&pkram_mutex); + list_for_each_entry_safe(page, tmp, &pkram_nodes, lru) { + node = page_address(page); + if (!(node->flags & PKRAM_ACCMODE_MASK)) + list_move(&page->lru, &dispose); + } + mutex_unlock(&pkram_mutex); + + while (!list_empty(&dispose)) { + page = list_first_entry(&dispose, struct page, lru); + list_del(&page->lru); + node = page_address(page); + pkram_truncate_node(node); + pkram_free_page(node); + } +} + static void pkram_add_link(struct pkram_link *link, struct pkram_obj *obj) { link->link_pfn = obj->link_pfn; @@ -1141,8 +1167,19 @@ static ssize_t show_pkram_sb_pfn(struct kobject *kobj, return sprintf(buf, "%lx\n", pfn); } +static ssize_t store_pkram_sb_pfn(struct kobject *kobj, + struct kobj_attribute *attr, const char *buf, size_t count) +{ + int val; + + if (kstrtoint(buf, 0, &val) || val) + return -EINVAL; + pkram_truncate(); + return count; +} + static struct kobj_attribute pkram_sb_pfn_attr = - __ATTR(pkram, 0444, show_pkram_sb_pfn, NULL); + __ATTR(pkram, 0644, show_pkram_sb_pfn, store_pkram_sb_pfn); static struct attribute *pkram_attrs[] = { &pkram_sb_pfn_attr.attr,