added some clean ups. == >From 45b8881201f73015c4e0352eb7e434f6e9c53fdd Mon Sep 17 00:00:00 2001 From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Date: Mon, 13 Jun 2011 10:09:17 +0900 Subject: [PATCH 2/5] [BUGFIX] memcg: fix init_page_cgroup nid with sparsemem commit 21a3c96 makes page_cgroup allocation as NUMA aware. But that caused a problem https://bugzilla.kernel.org/show_bug.cgi?id=36192. The problem was getting a NID from invalid struct pages, which was not initialized because it was out-of-node, out of [node_start_pfn, node_end_pfn) Now, with sparsemem, page_cgroup_init scans pfn from 0 to max_pfn. But this may scan a pfn which is not on any node and can access memmap which is not initialized. This makes page_cgroup_init() for SPARSEMEM node aware and remove a code to get nid from page->flags. (Then, we'll use valid NID always.) Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Changelog : - use better macros as node_start/end_pfn(), PAGE_SECTION_MASK..etc - pull out error handling code, which is rarely called. - fixed MEM_GOING_ONLINE case. - Add more comments and updated patch descriptions. --- mm/page_cgroup.c | 67 +++++++++++++++++++++++++++++++++++++++++------------- 1 files changed, 51 insertions(+), 16 deletions(-) diff --git a/mm/page_cgroup.c b/mm/page_cgroup.c index 74ccff6..0742633 100644 --- a/mm/page_cgroup.c +++ b/mm/page_cgroup.c @@ -162,13 +162,13 @@ static void free_page_cgroup(void *addr) } #endif -static int __meminit init_section_page_cgroup(unsigned long pfn) +static int __meminit init_section_page_cgroup(unsigned long pfn, int nid) { struct page_cgroup *base, *pc; struct mem_section *section; unsigned long table_size; unsigned long nr; - int nid, index; + int index; nr = pfn_to_section_nr(pfn); section = __nr_to_section(nr); @@ -176,7 +176,6 @@ static int __meminit init_section_page_cgroup(unsigned long pfn) if (section->page_cgroup) return 0; - nid = page_to_nid(pfn_to_page(pfn)); table_size = sizeof(struct page_cgroup) * PAGES_PER_SECTION; base = alloc_page_cgroup(table_size, nid); @@ -196,7 +195,11 @@ static int __meminit init_section_page_cgroup(unsigned long pfn) pc = base + index; init_page_cgroup(pc, nr); } - + /* + * Passed "pfn" may not be aligned to SECTION. For calculation, + * nedd to apply a mask. + */ + pfn &= PAGE_SECTION_MASK; section->page_cgroup = base - pfn; total_usage += table_size; return 0; @@ -225,10 +228,20 @@ int __meminit online_page_cgroup(unsigned long start_pfn, start = start_pfn & ~(PAGES_PER_SECTION - 1); end = ALIGN(start_pfn + nr_pages, PAGES_PER_SECTION); + if (nid == -1) { + /* + * In this case, "nid" already exists and contains valid memory. + * "start_pfn" passed for us is a pfn which is args for online_ + * _pages(), and start_pfn should exists. + */ + nid = pfn_to_nid(start_pfn); + VM_BUG_ON(!node_state(nid, N_ONLINE)); + } + for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) { if (!pfn_present(pfn)) continue; - fail = init_section_page_cgroup(pfn); + fail = init_section_page_cgroup(pfn, nid); } if (!fail) return 0; @@ -284,25 +297,47 @@ static int __meminit page_cgroup_callback(struct notifier_block *self, void __init page_cgroup_init(void) { unsigned long pfn; - int fail = 0; + int nid; if (mem_cgroup_disabled()) return; - for (pfn = 0; !fail && pfn < max_pfn; pfn += PAGES_PER_SECTION) { - if (!pfn_present(pfn)) - continue; - fail = init_section_page_cgroup(pfn); - } - if (fail) { - printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n"); - panic("Out of memory"); - } else { - hotplug_memory_notifier(page_cgroup_callback, 0); + for_each_node_state(nid, N_HIGH_MEMORY) { + unsigned long start_pfn, end_pfn; + + start_pfn = node_start_pfn(nid); + end_pfn = node_end_pfn(nid); + /* + * start_pfn and end_pfn may not be aligned to SECTION and + * page->flags of out of node pages are not initialized. So, + * we scan [start_pfn, the biggest section's pfn < end_pfn), here. + */ + for (pfn = start_pfn; + pfn < end_pfn; + pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) { + + if (!pfn_valid(pfn)) + continue; + /* + * Nodes's pfn can be overlapped. + * We know some arch can have nodes layout as + * -------------pfn--------------> + * N0 | N1 | N2 | N0 | N1 | N2|.... + */ + if (pfn_to_nid(pfn) != nid) + continue; + if (init_section_page_cgroup(pfn, nid)) + goto oom; + } } + hotplug_memory_notifier(page_cgroup_callback, 0); printk(KERN_INFO "allocated %ld bytes of page_cgroup\n", total_usage); printk(KERN_INFO "please try 'cgroup_disable=memory' option if you don't" " want memory cgroups\n"); + return; +oom: + printk(KERN_CRIT "try 'cgroup_disable=memory' boot option\n"); + panic("Out of memory"); } void __meminit pgdat_page_cgroup_init(struct pglist_data *pgdat) -- 1.7.4.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . 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