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Date: Wed, 6 May 2020 17:41:33 -0700 From: Anthony Yznaga <anthony.yznaga@...cle.com> To: linux-mm@...ck.org, linux-kernel@...r.kernel.org Cc: willy@...radead.org, corbet@....net, tglx@...utronix.de, mingo@...hat.com, bp@...en8.de, x86@...nel.org, hpa@...or.com, dave.hansen@...ux.intel.com, luto@...nel.org, peterz@...radead.org, rppt@...ux.ibm.com, akpm@...ux-foundation.org, hughd@...gle.com, ebiederm@...ssion.com, masahiroy@...nel.org, ardb@...nel.org, ndesaulniers@...gle.com, dima@...ovin.in, daniel.kiper@...cle.com, nivedita@...m.mit.edu, rafael.j.wysocki@...el.com, dan.j.williams@...el.com, zhenzhong.duan@...cle.com, jroedel@...e.de, bhe@...hat.com, guro@...com, Thomas.Lendacky@....com, andriy.shevchenko@...ux.intel.com, keescook@...omium.org, hannes@...xchg.org, minchan@...nel.org, mhocko@...nel.org, ying.huang@...el.com, yang.shi@...ux.alibaba.com, gustavo@...eddedor.com, ziqian.lzq@...fin.com, vdavydov.dev@...il.com, jason.zeng@...el.com, kevin.tian@...el.com, zhiyuan.lv@...el.com, lei.l.li@...el.com, paul.c.lai@...el.com, ashok.raj@...el.com, linux-fsdevel@...r.kernel.org, linux-doc@...r.kernel.org, kexec@...ts.infradead.org Subject: [RFC 07/43] mm: PKRAM: link nodes by pfn before reboot Since page structs are used for linking PKRAM nodes and cleared on boot, organize all PKRAM nodes into a list singly-linked by pfns before reboot to facilitate the node list restore in the new kernel. Originally-by: Vladimir Davydov <vdavydov.dev@...il.com> Signed-off-by: Anthony Yznaga <anthony.yznaga@...cle.com> --- mm/pkram.c | 50 ++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) diff --git a/mm/pkram.c b/mm/pkram.c index 06b471eea0b0..44fadb70acf6 100644 --- a/mm/pkram.c +++ b/mm/pkram.c @@ -2,12 +2,16 @@ #include <linux/err.h> #include <linux/gfp.h> #include <linux/highmem.h> +#include <linux/init.h> #include <linux/io.h> #include <linux/kernel.h> #include <linux/list.h> #include <linux/mm.h> +#include <linux/module.h> #include <linux/mutex.h> +#include <linux/notifier.h> #include <linux/pkram.h> +#include <linux/reboot.h> #include <linux/sched.h> #include <linux/string.h> #include <linux/types.h> @@ -58,11 +62,15 @@ struct pkram_obj { * singly-linked list of PKRAM link structures (see above), the node has a * pointer to the head of. * + * To facilitate data restore in the new kernel, before reboot all PKRAM nodes + * are organized into a list singly-linked by pfn's (see pkram_reboot()). + * * The structure occupies a memory page. */ struct pkram_node { __u32 flags; __u64 obj_pfn; /* points to the first obj of the node */ + __u64 node_pfn; /* points to the next node in the node list */ __u8 name[PKRAM_NAME_MAX]; }; @@ -71,6 +79,10 @@ struct pkram_node { #define PKRAM_LOAD 2 #define PKRAM_ACCMODE_MASK 3 +/* + * For convenience sake PKRAM nodes are kept in an auxiliary doubly-linked list + * connected through the lru field of the page struct. + */ static LIST_HEAD(pkram_nodes); /* linked through page::lru */ static DEFINE_MUTEX(pkram_mutex); /* serializes open/close */ @@ -679,3 +691,41 @@ size_t pkram_read(struct pkram_stream *ps, void *buf, size_t count) return copy_count; } + +/* + * Build the list of PKRAM nodes. + */ +static void __pkram_reboot(void) +{ + struct page *page; + struct pkram_node *node; + unsigned long node_pfn = 0; + + list_for_each_entry_reverse(page, &pkram_nodes, lru) { + node = page_address(page); + if (WARN_ON(node->flags & PKRAM_ACCMODE_MASK)) + continue; + node->node_pfn = node_pfn; + node_pfn = page_to_pfn(page); + } +} + +static int pkram_reboot(struct notifier_block *notifier, + unsigned long val, void *v) +{ + if (val != SYS_RESTART) + return NOTIFY_DONE; + __pkram_reboot(); + return NOTIFY_OK; +} + +static struct notifier_block pkram_reboot_notifier = { + .notifier_call = pkram_reboot, +}; + +static int __init pkram_init(void) +{ + register_reboot_notifier(&pkram_reboot_notifier); + return 0; +} +module_init(pkram_init); -- 2.13.3
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