From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from userp2130.oracle.com ([156.151.31.86]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jWUeU-0008W4-8J for kexec@lists.infradead.org; Thu, 07 May 2020 00:44:40 +0000 From: Anthony Yznaga Subject: [RFC 02/43] mm: PKRAM: implement node load and save functions Date: Wed, 6 May 2020 17:41:28 -0700 Message-Id: <1588812129-8596-3-git-send-email-anthony.yznaga@oracle.com> In-Reply-To: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> References: <1588812129-8596-1-git-send-email-anthony.yznaga@oracle.com> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "kexec" Errors-To: kexec-bounces+dwmw2=infradead.org@lists.infradead.org To: linux-mm@kvack.org, linux-kernel@vger.kernel.org Cc: x86@kernel.org, linux-doc@vger.kernel.org, gustavo@embeddedor.com, peterz@infradead.org, kexec@lists.infradead.org, paul.c.lai@intel.com, dave.hansen@linux.intel.com, mhocko@kernel.org, lei.l.li@intel.com, nivedita@alum.mit.edu, ziqian.lzq@antfin.com, hpa@zytor.com, ardb@kernel.org, ashok.raj@intel.com, bhe@redhat.com, corbet@lwn.net, masahiroy@kernel.org, rafael.j.wysocki@intel.com, hughd@google.com, willy@infradead.org, rppt@linux.ibm.com, mingo@redhat.com, vdavydov.dev@gmail.com, ying.huang@intel.com, Thomas.Lendacky@amd.com, kevin.tian@intel.com, jroedel@suse.de, keescook@chromium.org, dan.j.williams@intel.com, bp@alien8.de, zhiyuan.lv@intel.com, luto@kernel.org, tglx@linutronix.de, andriy.shevchenko@linux.intel.com, dima@golovin.in, yang.shi@linux.alibaba.com, ndesaulniers@google.com, zhenzhong.duan@oracle.com, guro@fb.com, minchan@kernel.org, ebiederm@xmission.com, jason.zeng@intel.com, hannes@cmpxchg.org, linux-fsdevel@vger.kernel.org, akpm@linux-foundation.org, daniel.kiper@oracle.com Preserved memory is divided into nodes which can be saved and loaded independently of each other. PKRAM nodes are kept on a list and identified by unique names. Whenever a save operation is initiated by calling pkram_prepare_save(), a new node is created and linked to the list. When the save operation has been committed by calling pkram_finish_save(), the node becomes loadable. A load operation can be then initiated by calling pkram_prepare_load() which deletes the node from the list and prepares the corresponding stream for loading data from it. After the load has been finished, the pkram_finish_load() function must be called to free the node. Nodes are also deleted when a save operation is discarded, i.e. pkram_discard_save() is called instead of pkram_finish_save(). Originally-by: Vladimir Davydov Signed-off-by: Anthony Yznaga --- include/linux/pkram.h | 7 ++- mm/pkram.c | 148 ++++++++++++++++++++++++++++++++++++++++++++++++-- 2 files changed, 149 insertions(+), 6 deletions(-) diff --git a/include/linux/pkram.h b/include/linux/pkram.h index 4c4e13311ec8..83a0579e4c1c 100644 --- a/include/linux/pkram.h +++ b/include/linux/pkram.h @@ -6,7 +6,12 @@ #include #include -struct pkram_stream; +struct pkram_node; + +struct pkram_stream { + gfp_t gfp_mask; + struct pkram_node *node; +}; #define PKRAM_NAME_MAX 256 /* including nul */ diff --git a/mm/pkram.c b/mm/pkram.c index d6f2f79d4852..5c57126353ff 100644 --- a/mm/pkram.c +++ b/mm/pkram.c @@ -2,16 +2,85 @@ #include #include #include +#include #include +#include #include +#include #include +/* + * Preserved memory is divided into nodes that can be saved or loaded + * independently of each other. The nodes are identified by unique name + * strings. + * + * The structure occupies a memory page. + */ +struct pkram_node { + __u32 flags; + + __u8 name[PKRAM_NAME_MAX]; +}; + +#define PKRAM_SAVE 1 +#define PKRAM_LOAD 2 +#define PKRAM_ACCMODE_MASK 3 + +static LIST_HEAD(pkram_nodes); /* linked through page::lru */ +static DEFINE_MUTEX(pkram_mutex); /* serializes open/close */ + +static inline struct page *pkram_alloc_page(gfp_t gfp_mask) +{ + return alloc_page(gfp_mask); +} + +static inline void pkram_free_page(void *addr) +{ + free_page((unsigned long)addr); +} + +static inline void pkram_insert_node(struct pkram_node *node) +{ + list_add(&virt_to_page(node)->lru, &pkram_nodes); +} + +static inline void pkram_delete_node(struct pkram_node *node) +{ + list_del(&virt_to_page(node)->lru); +} + +static struct pkram_node *pkram_find_node(const char *name) +{ + struct page *page; + struct pkram_node *node; + + list_for_each_entry(page, &pkram_nodes, lru) { + node = page_address(page); + if (strcmp(node->name, name) == 0) + return node; + } + return NULL; +} + +static void pkram_stream_init(struct pkram_stream *ps, + struct pkram_node *node, gfp_t gfp_mask) +{ + memset(ps, 0, sizeof(*ps)); + ps->gfp_mask = gfp_mask; + ps->node = node; +} + /** * Create a preserved memory node with name @name and initialize stream @ps * for saving data to it. * * @gfp_mask specifies the memory allocation mask to be used when saving data. * + * Error values: + * %ENAMETOOLONG: name len >= PKRAM_NAME_MAX + * %ENOMEM: insufficient memory available + * %EEXIST: node with specified name already exists + * * Returns 0 on success, -errno on failure. * * After the save has finished, pkram_finish_save() (or pkram_discard_save() in @@ -19,7 +88,34 @@ */ int pkram_prepare_save(struct pkram_stream *ps, const char *name, gfp_t gfp_mask) { - return -ENOSYS; + struct page *page; + struct pkram_node *node; + int err = 0; + + if (strlen(name) >= PKRAM_NAME_MAX) + return -ENAMETOOLONG; + + page = pkram_alloc_page(GFP_KERNEL | __GFP_ZERO); + if (!page) + return -ENOMEM; + node = page_address(page); + + node->flags = PKRAM_SAVE; + strcpy(node->name, name); + + mutex_lock(&pkram_mutex); + if (!pkram_find_node(name)) + pkram_insert_node(node); + else + err = -EEXIST; + mutex_unlock(&pkram_mutex); + if (err) { + __free_page(page); + return err; + } + + pkram_stream_init(ps, node, gfp_mask); + return 0; } /** @@ -50,7 +146,12 @@ void pkram_finish_save_obj(struct pkram_stream *ps) */ void pkram_finish_save(struct pkram_stream *ps) { - BUG(); + struct pkram_node *node = ps->node; + + BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE); + + smp_wmb(); + node->flags &= ~PKRAM_ACCMODE_MASK; } /** @@ -60,7 +161,15 @@ void pkram_finish_save(struct pkram_stream *ps) */ void pkram_discard_save(struct pkram_stream *ps) { - BUG(); + struct pkram_node *node = ps->node; + + BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_SAVE); + + mutex_lock(&pkram_mutex); + pkram_delete_node(node); + mutex_unlock(&pkram_mutex); + + pkram_free_page(node); } /** @@ -69,11 +178,36 @@ void pkram_discard_save(struct pkram_stream *ps) * * Returns 0 on success, -errno on failure. * + * Error values: + * %ENOENT: node with specified name does not exist + * %EBUSY: save to required node has not finished yet + * * After the load has finished, pkram_finish_load() is to be called. */ int pkram_prepare_load(struct pkram_stream *ps, const char *name) { - return -ENOSYS; + struct pkram_node *node; + int err = 0; + + mutex_lock(&pkram_mutex); + node = pkram_find_node(name); + if (!node) { + err = -ENOENT; + goto out_unlock; + } + if (node->flags & PKRAM_ACCMODE_MASK) { + err = -EBUSY; + goto out_unlock; + } + pkram_delete_node(node); +out_unlock: + mutex_unlock(&pkram_mutex); + if (err) + return err; + + node->flags |= PKRAM_LOAD; + pkram_stream_init(ps, node, 0); + return 0; } /** @@ -106,7 +240,11 @@ void pkram_finish_load_obj(struct pkram_stream *ps) */ void pkram_finish_load(struct pkram_stream *ps) { - BUG(); + struct pkram_node *node = ps->node; + + BUG_ON((node->flags & PKRAM_ACCMODE_MASK) != PKRAM_LOAD); + + pkram_free_page(node); } /** -- 2.13.3 _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec