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![Sergei Rogachev](/assets/img/avatar_default.png)
Page owner uses the page_ext structure to keep meta-information for every page in the system. The structure also contains a field of type 'struct stack_trace', page owner uses this field during invocation of the function save_stack_trace. It is easy to notice that keeping a copy of this structure for every page in the system is very inefficiently in terms of memory. The patch removes this unnecessary field of page_ext and forces page owner to use a stack_trace structure allocated on the stack. [akpm@linux-foundation.org: use struct initializers] Signed-off-by: Sergei Rogachev <rogachevsergei@gmail.com> Acked-by: Joonsoo Kim <iamjoonsoo.kim@lge.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
313 lines
7 KiB
C
313 lines
7 KiB
C
#include <linux/debugfs.h>
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#include <linux/mm.h>
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#include <linux/slab.h>
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#include <linux/uaccess.h>
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#include <linux/bootmem.h>
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#include <linux/stacktrace.h>
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#include <linux/page_owner.h>
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#include "internal.h"
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static bool page_owner_disabled = true;
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bool page_owner_inited __read_mostly;
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static void init_early_allocated_pages(void);
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static int early_page_owner_param(char *buf)
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{
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if (!buf)
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return -EINVAL;
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if (strcmp(buf, "on") == 0)
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page_owner_disabled = false;
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return 0;
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}
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early_param("page_owner", early_page_owner_param);
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static bool need_page_owner(void)
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{
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if (page_owner_disabled)
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return false;
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return true;
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}
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static void init_page_owner(void)
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{
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if (page_owner_disabled)
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return;
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page_owner_inited = true;
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init_early_allocated_pages();
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}
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struct page_ext_operations page_owner_ops = {
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.need = need_page_owner,
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.init = init_page_owner,
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};
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void __reset_page_owner(struct page *page, unsigned int order)
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{
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int i;
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struct page_ext *page_ext;
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for (i = 0; i < (1 << order); i++) {
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page_ext = lookup_page_ext(page + i);
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__clear_bit(PAGE_EXT_OWNER, &page_ext->flags);
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}
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}
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void __set_page_owner(struct page *page, unsigned int order, gfp_t gfp_mask)
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{
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struct page_ext *page_ext = lookup_page_ext(page);
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struct stack_trace trace = {
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.nr_entries = 0,
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.max_entries = ARRAY_SIZE(page_ext->trace_entries),
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.entries = &page_ext->trace_entries[0],
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.skip = 3,
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};
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save_stack_trace(&trace);
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page_ext->order = order;
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page_ext->gfp_mask = gfp_mask;
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page_ext->nr_entries = trace.nr_entries;
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__set_bit(PAGE_EXT_OWNER, &page_ext->flags);
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}
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static ssize_t
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print_page_owner(char __user *buf, size_t count, unsigned long pfn,
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struct page *page, struct page_ext *page_ext)
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{
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int ret;
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int pageblock_mt, page_mt;
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char *kbuf;
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struct stack_trace trace = {
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.nr_entries = page_ext->nr_entries,
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.entries = &page_ext->trace_entries[0],
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};
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kbuf = kmalloc(count, GFP_KERNEL);
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if (!kbuf)
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return -ENOMEM;
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ret = snprintf(kbuf, count,
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"Page allocated via order %u, mask 0x%x\n",
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page_ext->order, page_ext->gfp_mask);
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if (ret >= count)
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goto err;
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/* Print information relevant to grouping pages by mobility */
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pageblock_mt = get_pfnblock_migratetype(page, pfn);
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page_mt = gfpflags_to_migratetype(page_ext->gfp_mask);
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ret += snprintf(kbuf + ret, count - ret,
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"PFN %lu Block %lu type %d %s Flags %s%s%s%s%s%s%s%s%s%s%s%s\n",
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pfn,
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pfn >> pageblock_order,
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pageblock_mt,
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pageblock_mt != page_mt ? "Fallback" : " ",
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PageLocked(page) ? "K" : " ",
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PageError(page) ? "E" : " ",
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PageReferenced(page) ? "R" : " ",
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PageUptodate(page) ? "U" : " ",
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PageDirty(page) ? "D" : " ",
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PageLRU(page) ? "L" : " ",
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PageActive(page) ? "A" : " ",
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PageSlab(page) ? "S" : " ",
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PageWriteback(page) ? "W" : " ",
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PageCompound(page) ? "C" : " ",
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PageSwapCache(page) ? "B" : " ",
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PageMappedToDisk(page) ? "M" : " ");
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if (ret >= count)
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goto err;
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ret += snprint_stack_trace(kbuf + ret, count - ret, &trace, 0);
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if (ret >= count)
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goto err;
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ret += snprintf(kbuf + ret, count - ret, "\n");
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if (ret >= count)
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goto err;
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if (copy_to_user(buf, kbuf, ret))
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ret = -EFAULT;
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kfree(kbuf);
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return ret;
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err:
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kfree(kbuf);
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return -ENOMEM;
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}
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static ssize_t
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read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos)
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{
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unsigned long pfn;
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struct page *page;
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struct page_ext *page_ext;
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if (!page_owner_inited)
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return -EINVAL;
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page = NULL;
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pfn = min_low_pfn + *ppos;
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/* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */
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while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0)
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pfn++;
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drain_all_pages(NULL);
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/* Find an allocated page */
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for (; pfn < max_pfn; pfn++) {
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/*
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* If the new page is in a new MAX_ORDER_NR_PAGES area,
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* validate the area as existing, skip it if not
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*/
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if ((pfn & (MAX_ORDER_NR_PAGES - 1)) == 0 && !pfn_valid(pfn)) {
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pfn += MAX_ORDER_NR_PAGES - 1;
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continue;
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}
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/* Check for holes within a MAX_ORDER area */
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if (!pfn_valid_within(pfn))
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continue;
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page = pfn_to_page(pfn);
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if (PageBuddy(page)) {
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unsigned long freepage_order = page_order_unsafe(page);
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if (freepage_order < MAX_ORDER)
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pfn += (1UL << freepage_order) - 1;
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continue;
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}
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page_ext = lookup_page_ext(page);
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/*
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* Some pages could be missed by concurrent allocation or free,
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* because we don't hold the zone lock.
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*/
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if (!test_bit(PAGE_EXT_OWNER, &page_ext->flags))
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continue;
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/* Record the next PFN to read in the file offset */
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*ppos = (pfn - min_low_pfn) + 1;
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return print_page_owner(buf, count, pfn, page, page_ext);
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}
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return 0;
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}
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static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone)
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{
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struct page *page;
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struct page_ext *page_ext;
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unsigned long pfn = zone->zone_start_pfn, block_end_pfn;
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unsigned long end_pfn = pfn + zone->spanned_pages;
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unsigned long count = 0;
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/* Scan block by block. First and last block may be incomplete */
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pfn = zone->zone_start_pfn;
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/*
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* Walk the zone in pageblock_nr_pages steps. If a page block spans
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* a zone boundary, it will be double counted between zones. This does
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* not matter as the mixed block count will still be correct
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*/
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for (; pfn < end_pfn; ) {
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if (!pfn_valid(pfn)) {
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pfn = ALIGN(pfn + 1, MAX_ORDER_NR_PAGES);
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continue;
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}
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block_end_pfn = ALIGN(pfn + 1, pageblock_nr_pages);
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block_end_pfn = min(block_end_pfn, end_pfn);
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page = pfn_to_page(pfn);
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for (; pfn < block_end_pfn; pfn++) {
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if (!pfn_valid_within(pfn))
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continue;
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page = pfn_to_page(pfn);
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/*
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* We are safe to check buddy flag and order, because
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* this is init stage and only single thread runs.
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*/
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if (PageBuddy(page)) {
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pfn += (1UL << page_order(page)) - 1;
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continue;
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}
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if (PageReserved(page))
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continue;
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page_ext = lookup_page_ext(page);
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/* Maybe overraping zone */
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if (test_bit(PAGE_EXT_OWNER, &page_ext->flags))
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continue;
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/* Found early allocated page */
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set_page_owner(page, 0, 0);
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count++;
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}
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}
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pr_info("Node %d, zone %8s: page owner found early allocated %lu pages\n",
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pgdat->node_id, zone->name, count);
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}
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static void init_zones_in_node(pg_data_t *pgdat)
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{
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struct zone *zone;
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struct zone *node_zones = pgdat->node_zones;
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unsigned long flags;
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for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
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if (!populated_zone(zone))
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continue;
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spin_lock_irqsave(&zone->lock, flags);
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init_pages_in_zone(pgdat, zone);
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spin_unlock_irqrestore(&zone->lock, flags);
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}
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}
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static void init_early_allocated_pages(void)
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{
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pg_data_t *pgdat;
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drain_all_pages(NULL);
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for_each_online_pgdat(pgdat)
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init_zones_in_node(pgdat);
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}
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static const struct file_operations proc_page_owner_operations = {
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.read = read_page_owner,
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};
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static int __init pageowner_init(void)
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{
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struct dentry *dentry;
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if (!page_owner_inited) {
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pr_info("page_owner is disabled\n");
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return 0;
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}
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dentry = debugfs_create_file("page_owner", S_IRUSR, NULL,
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NULL, &proc_page_owner_operations);
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if (IS_ERR(dentry))
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return PTR_ERR(dentry);
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return 0;
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}
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module_init(pageowner_init)
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