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![Joonsoo Kim](/assets/img/avatar_default.png)
This is the page owner tracking code which is introduced so far ago. It is resident on Andrew's tree, though, nobody tried to upstream so it remain as is. Our company uses this feature actively to debug memory leak or to find a memory hogger so I decide to upstream this feature. This functionality help us to know who allocates the page. When allocating a page, we store some information about allocation in extra memory. Later, if we need to know status of all pages, we can get and analyze it from this stored information. In previous version of this feature, extra memory is statically defined in struct page, but, in this version, extra memory is allocated outside of struct page. It enables us to turn on/off this feature at boottime without considerable memory waste. Although we already have tracepoint for tracing page allocation/free, using it to analyze page owner is rather complex. We need to enlarge the trace buffer for preventing overlapping until userspace program launched. And, launched program continually dump out the trace buffer for later analysis and it would change system behaviour with more possibility rather than just keeping it in memory, so bad for debug. Moreover, we can use page_owner feature further for various purposes. For example, we can use it for fragmentation statistics implemented in this patch. And, I also plan to implement some CMA failure debugging feature using this interface. I'd like to give the credit for all developers contributed this feature, but, it's not easy because I don't know exact history. Sorry about that. Below is people who has "Signed-off-by" in the patches in Andrew's tree. Contributor: Alexander Nyberg <alexn@dsv.su.se> Mel Gorman <mgorman@suse.de> Dave Hansen <dave@linux.vnet.ibm.com> Minchan Kim <minchan@kernel.org> Michal Nazarewicz <mina86@mina86.com> Andrew Morton <akpm@linux-foundation.org> Jungsoo Son <jungsoo.son@lge.com> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Minchan Kim <minchan@kernel.org> Cc: Dave Hansen <dave@sr71.net> Cc: Michal Nazarewicz <mina86@mina86.com> Cc: Jungsoo Son <jungsoo.son@lge.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
403 lines
10 KiB
C
403 lines
10 KiB
C
#include <linux/mm.h>
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#include <linux/mmzone.h>
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#include <linux/bootmem.h>
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#include <linux/page_ext.h>
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#include <linux/memory.h>
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#include <linux/vmalloc.h>
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#include <linux/kmemleak.h>
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#include <linux/page_owner.h>
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/*
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* struct page extension
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*
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* This is the feature to manage memory for extended data per page.
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*
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* Until now, we must modify struct page itself to store extra data per page.
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* This requires rebuilding the kernel and it is really time consuming process.
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* And, sometimes, rebuild is impossible due to third party module dependency.
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* At last, enlarging struct page could cause un-wanted system behaviour change.
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*
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* This feature is intended to overcome above mentioned problems. This feature
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* allocates memory for extended data per page in certain place rather than
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* the struct page itself. This memory can be accessed by the accessor
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* functions provided by this code. During the boot process, it checks whether
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* allocation of huge chunk of memory is needed or not. If not, it avoids
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* allocating memory at all. With this advantage, we can include this feature
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* into the kernel in default and can avoid rebuild and solve related problems.
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*
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* To help these things to work well, there are two callbacks for clients. One
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* is the need callback which is mandatory if user wants to avoid useless
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* memory allocation at boot-time. The other is optional, init callback, which
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* is used to do proper initialization after memory is allocated.
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*
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* The need callback is used to decide whether extended memory allocation is
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* needed or not. Sometimes users want to deactivate some features in this
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* boot and extra memory would be unneccessary. In this case, to avoid
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* allocating huge chunk of memory, each clients represent their need of
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* extra memory through the need callback. If one of the need callbacks
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* returns true, it means that someone needs extra memory so that
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* page extension core should allocates memory for page extension. If
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* none of need callbacks return true, memory isn't needed at all in this boot
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* and page extension core can skip to allocate memory. As result,
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* none of memory is wasted.
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*
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* The init callback is used to do proper initialization after page extension
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* is completely initialized. In sparse memory system, extra memory is
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* allocated some time later than memmap is allocated. In other words, lifetime
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* of memory for page extension isn't same with memmap for struct page.
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* Therefore, clients can't store extra data until page extension is
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* initialized, even if pages are allocated and used freely. This could
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* cause inadequate state of extra data per page, so, to prevent it, client
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* can utilize this callback to initialize the state of it correctly.
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*/
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static struct page_ext_operations *page_ext_ops[] = {
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&debug_guardpage_ops,
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#ifdef CONFIG_PAGE_POISONING
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&page_poisoning_ops,
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#endif
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#ifdef CONFIG_PAGE_OWNER
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&page_owner_ops,
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#endif
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};
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static unsigned long total_usage;
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static bool __init invoke_need_callbacks(void)
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{
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int i;
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int entries = ARRAY_SIZE(page_ext_ops);
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for (i = 0; i < entries; i++) {
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if (page_ext_ops[i]->need && page_ext_ops[i]->need())
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return true;
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}
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return false;
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}
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static void __init invoke_init_callbacks(void)
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{
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int i;
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int entries = ARRAY_SIZE(page_ext_ops);
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for (i = 0; i < entries; i++) {
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if (page_ext_ops[i]->init)
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page_ext_ops[i]->init();
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}
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}
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#if !defined(CONFIG_SPARSEMEM)
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void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
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{
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pgdat->node_page_ext = NULL;
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}
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struct page_ext *lookup_page_ext(struct page *page)
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{
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unsigned long pfn = page_to_pfn(page);
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unsigned long offset;
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struct page_ext *base;
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base = NODE_DATA(page_to_nid(page))->node_page_ext;
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#ifdef CONFIG_DEBUG_VM
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/*
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* The sanity checks the page allocator does upon freeing a
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* page can reach here before the page_ext arrays are
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* allocated when feeding a range of pages to the allocator
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* for the first time during bootup or memory hotplug.
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*/
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if (unlikely(!base))
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return NULL;
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#endif
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offset = pfn - round_down(node_start_pfn(page_to_nid(page)),
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MAX_ORDER_NR_PAGES);
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return base + offset;
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}
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static int __init alloc_node_page_ext(int nid)
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{
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struct page_ext *base;
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unsigned long table_size;
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unsigned long nr_pages;
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nr_pages = NODE_DATA(nid)->node_spanned_pages;
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if (!nr_pages)
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return 0;
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/*
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* Need extra space if node range is not aligned with
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* MAX_ORDER_NR_PAGES. When page allocator's buddy algorithm
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* checks buddy's status, range could be out of exact node range.
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*/
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if (!IS_ALIGNED(node_start_pfn(nid), MAX_ORDER_NR_PAGES) ||
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!IS_ALIGNED(node_end_pfn(nid), MAX_ORDER_NR_PAGES))
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nr_pages += MAX_ORDER_NR_PAGES;
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table_size = sizeof(struct page_ext) * nr_pages;
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base = memblock_virt_alloc_try_nid_nopanic(
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table_size, PAGE_SIZE, __pa(MAX_DMA_ADDRESS),
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BOOTMEM_ALLOC_ACCESSIBLE, nid);
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if (!base)
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return -ENOMEM;
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NODE_DATA(nid)->node_page_ext = base;
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total_usage += table_size;
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return 0;
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}
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void __init page_ext_init_flatmem(void)
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{
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int nid, fail;
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if (!invoke_need_callbacks())
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return;
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for_each_online_node(nid) {
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fail = alloc_node_page_ext(nid);
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if (fail)
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goto fail;
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}
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pr_info("allocated %ld bytes of page_ext\n", total_usage);
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invoke_init_callbacks();
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return;
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fail:
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pr_crit("allocation of page_ext failed.\n");
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panic("Out of memory");
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}
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#else /* CONFIG_FLAT_NODE_MEM_MAP */
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struct page_ext *lookup_page_ext(struct page *page)
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{
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unsigned long pfn = page_to_pfn(page);
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struct mem_section *section = __pfn_to_section(pfn);
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#ifdef CONFIG_DEBUG_VM
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/*
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* The sanity checks the page allocator does upon freeing a
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* page can reach here before the page_ext arrays are
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* allocated when feeding a range of pages to the allocator
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* for the first time during bootup or memory hotplug.
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*/
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if (!section->page_ext)
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return NULL;
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#endif
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return section->page_ext + pfn;
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}
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static void *__meminit alloc_page_ext(size_t size, int nid)
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{
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gfp_t flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN;
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void *addr = NULL;
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addr = alloc_pages_exact_nid(nid, size, flags);
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if (addr) {
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kmemleak_alloc(addr, size, 1, flags);
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return addr;
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}
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if (node_state(nid, N_HIGH_MEMORY))
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addr = vzalloc_node(size, nid);
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else
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addr = vzalloc(size);
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return addr;
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}
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static int __meminit init_section_page_ext(unsigned long pfn, int nid)
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{
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struct mem_section *section;
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struct page_ext *base;
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unsigned long table_size;
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section = __pfn_to_section(pfn);
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if (section->page_ext)
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return 0;
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table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
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base = alloc_page_ext(table_size, nid);
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/*
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* The value stored in section->page_ext is (base - pfn)
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* and it does not point to the memory block allocated above,
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* causing kmemleak false positives.
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*/
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kmemleak_not_leak(base);
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if (!base) {
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pr_err("page ext allocation failure\n");
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return -ENOMEM;
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}
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/*
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* The passed "pfn" may not be aligned to SECTION. For the calculation
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* we need to apply a mask.
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*/
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pfn &= PAGE_SECTION_MASK;
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section->page_ext = base - pfn;
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total_usage += table_size;
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return 0;
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}
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#ifdef CONFIG_MEMORY_HOTPLUG
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static void free_page_ext(void *addr)
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{
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if (is_vmalloc_addr(addr)) {
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vfree(addr);
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} else {
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struct page *page = virt_to_page(addr);
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size_t table_size;
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table_size = sizeof(struct page_ext) * PAGES_PER_SECTION;
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BUG_ON(PageReserved(page));
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free_pages_exact(addr, table_size);
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}
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}
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static void __free_page_ext(unsigned long pfn)
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{
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struct mem_section *ms;
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struct page_ext *base;
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ms = __pfn_to_section(pfn);
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if (!ms || !ms->page_ext)
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return;
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base = ms->page_ext + pfn;
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free_page_ext(base);
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ms->page_ext = NULL;
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}
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static int __meminit online_page_ext(unsigned long start_pfn,
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unsigned long nr_pages,
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int nid)
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{
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unsigned long start, end, pfn;
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int fail = 0;
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start = SECTION_ALIGN_DOWN(start_pfn);
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end = SECTION_ALIGN_UP(start_pfn + nr_pages);
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if (nid == -1) {
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/*
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* In this case, "nid" already exists and contains valid memory.
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* "start_pfn" passed to us is a pfn which is an arg for
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* online__pages(), and start_pfn should exist.
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*/
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nid = pfn_to_nid(start_pfn);
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VM_BUG_ON(!node_state(nid, N_ONLINE));
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}
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for (pfn = start; !fail && pfn < end; pfn += PAGES_PER_SECTION) {
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if (!pfn_present(pfn))
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continue;
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fail = init_section_page_ext(pfn, nid);
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}
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if (!fail)
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return 0;
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/* rollback */
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for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
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__free_page_ext(pfn);
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return -ENOMEM;
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}
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static int __meminit offline_page_ext(unsigned long start_pfn,
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unsigned long nr_pages, int nid)
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{
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unsigned long start, end, pfn;
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start = SECTION_ALIGN_DOWN(start_pfn);
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end = SECTION_ALIGN_UP(start_pfn + nr_pages);
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for (pfn = start; pfn < end; pfn += PAGES_PER_SECTION)
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__free_page_ext(pfn);
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return 0;
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}
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static int __meminit page_ext_callback(struct notifier_block *self,
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unsigned long action, void *arg)
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{
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struct memory_notify *mn = arg;
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int ret = 0;
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switch (action) {
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case MEM_GOING_ONLINE:
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ret = online_page_ext(mn->start_pfn,
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mn->nr_pages, mn->status_change_nid);
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break;
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case MEM_OFFLINE:
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offline_page_ext(mn->start_pfn,
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mn->nr_pages, mn->status_change_nid);
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break;
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case MEM_CANCEL_ONLINE:
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offline_page_ext(mn->start_pfn,
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mn->nr_pages, mn->status_change_nid);
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break;
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case MEM_GOING_OFFLINE:
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break;
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case MEM_ONLINE:
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case MEM_CANCEL_OFFLINE:
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break;
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}
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return notifier_from_errno(ret);
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}
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#endif
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void __init page_ext_init(void)
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{
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unsigned long pfn;
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int nid;
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if (!invoke_need_callbacks())
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return;
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for_each_node_state(nid, N_MEMORY) {
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unsigned long start_pfn, end_pfn;
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start_pfn = node_start_pfn(nid);
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end_pfn = node_end_pfn(nid);
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/*
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* start_pfn and end_pfn may not be aligned to SECTION and the
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* page->flags of out of node pages are not initialized. So we
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* scan [start_pfn, the biggest section's pfn < end_pfn) here.
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*/
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for (pfn = start_pfn; pfn < end_pfn;
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pfn = ALIGN(pfn + 1, PAGES_PER_SECTION)) {
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if (!pfn_valid(pfn))
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continue;
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/*
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* Nodes's pfns can be overlapping.
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* We know some arch can have a nodes layout such as
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* -------------pfn-------------->
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* N0 | N1 | N2 | N0 | N1 | N2|....
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*/
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if (pfn_to_nid(pfn) != nid)
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continue;
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if (init_section_page_ext(pfn, nid))
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goto oom;
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}
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}
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hotplug_memory_notifier(page_ext_callback, 0);
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pr_info("allocated %ld bytes of page_ext\n", total_usage);
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invoke_init_callbacks();
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return;
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oom:
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panic("Out of memory");
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}
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void __meminit pgdat_page_ext_init(struct pglist_data *pgdat)
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{
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}
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#endif
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