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5f24ce5fd3
PG_buddy can be converted to _mapcount == -2. So the PG_compound_lock can be added to page->flags without overflowing (because of the sparse section bits increasing) with CONFIG_X86_PAE=y and CONFIG_X86_PAT=y. This also has to move the memory hotplug code from _mapcount to lru.next to avoid any risk of clashes. We can't use lru.next for PG_buddy removal, but memory hotplug can use lru.next even more easily than the mapcount instead. Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
213 lines
4.9 KiB
C
213 lines
4.9 KiB
C
#include <linux/bootmem.h>
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#include <linux/compiler.h>
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#include <linux/fs.h>
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#include <linux/init.h>
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#include <linux/ksm.h>
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#include <linux/mm.h>
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#include <linux/mmzone.h>
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#include <linux/proc_fs.h>
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#include <linux/seq_file.h>
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#include <linux/hugetlb.h>
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#include <linux/kernel-page-flags.h>
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#include <asm/uaccess.h>
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#include "internal.h"
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#define KPMSIZE sizeof(u64)
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#define KPMMASK (KPMSIZE - 1)
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/* /proc/kpagecount - an array exposing page counts
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*
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* Each entry is a u64 representing the corresponding
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* physical page count.
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*/
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static ssize_t kpagecount_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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u64 __user *out = (u64 __user *)buf;
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struct page *ppage;
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unsigned long src = *ppos;
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unsigned long pfn;
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ssize_t ret = 0;
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u64 pcount;
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pfn = src / KPMSIZE;
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count = min_t(size_t, count, (max_pfn * KPMSIZE) - src);
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if (src & KPMMASK || count & KPMMASK)
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return -EINVAL;
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while (count > 0) {
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if (pfn_valid(pfn))
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ppage = pfn_to_page(pfn);
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else
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ppage = NULL;
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if (!ppage || PageSlab(ppage))
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pcount = 0;
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else
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pcount = page_mapcount(ppage);
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if (put_user(pcount, out)) {
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ret = -EFAULT;
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break;
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}
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pfn++;
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out++;
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count -= KPMSIZE;
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}
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*ppos += (char __user *)out - buf;
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if (!ret)
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ret = (char __user *)out - buf;
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return ret;
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}
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static const struct file_operations proc_kpagecount_operations = {
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.llseek = mem_lseek,
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.read = kpagecount_read,
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};
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/* /proc/kpageflags - an array exposing page flags
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*
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* Each entry is a u64 representing the corresponding
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* physical page flags.
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*/
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static inline u64 kpf_copy_bit(u64 kflags, int ubit, int kbit)
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{
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return ((kflags >> kbit) & 1) << ubit;
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}
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u64 stable_page_flags(struct page *page)
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{
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u64 k;
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u64 u;
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/*
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* pseudo flag: KPF_NOPAGE
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* it differentiates a memory hole from a page with no flags
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*/
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if (!page)
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return 1 << KPF_NOPAGE;
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k = page->flags;
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u = 0;
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/*
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* pseudo flags for the well known (anonymous) memory mapped pages
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*
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* Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
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* simple test in page_mapped() is not enough.
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*/
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if (!PageSlab(page) && page_mapped(page))
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u |= 1 << KPF_MMAP;
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if (PageAnon(page))
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u |= 1 << KPF_ANON;
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if (PageKsm(page))
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u |= 1 << KPF_KSM;
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/*
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* compound pages: export both head/tail info
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* they together define a compound page's start/end pos and order
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*/
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if (PageHead(page))
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u |= 1 << KPF_COMPOUND_HEAD;
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if (PageTail(page))
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u |= 1 << KPF_COMPOUND_TAIL;
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if (PageHuge(page))
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u |= 1 << KPF_HUGE;
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/*
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* Caveats on high order pages: page->_count will only be set
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* -1 on the head page; SLUB/SLQB do the same for PG_slab;
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* SLOB won't set PG_slab at all on compound pages.
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*/
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if (PageBuddy(page))
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u |= 1 << KPF_BUDDY;
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u |= kpf_copy_bit(k, KPF_LOCKED, PG_locked);
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u |= kpf_copy_bit(k, KPF_SLAB, PG_slab);
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u |= kpf_copy_bit(k, KPF_ERROR, PG_error);
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u |= kpf_copy_bit(k, KPF_DIRTY, PG_dirty);
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u |= kpf_copy_bit(k, KPF_UPTODATE, PG_uptodate);
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u |= kpf_copy_bit(k, KPF_WRITEBACK, PG_writeback);
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u |= kpf_copy_bit(k, KPF_LRU, PG_lru);
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u |= kpf_copy_bit(k, KPF_REFERENCED, PG_referenced);
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u |= kpf_copy_bit(k, KPF_ACTIVE, PG_active);
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u |= kpf_copy_bit(k, KPF_RECLAIM, PG_reclaim);
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u |= kpf_copy_bit(k, KPF_SWAPCACHE, PG_swapcache);
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u |= kpf_copy_bit(k, KPF_SWAPBACKED, PG_swapbacked);
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u |= kpf_copy_bit(k, KPF_UNEVICTABLE, PG_unevictable);
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u |= kpf_copy_bit(k, KPF_MLOCKED, PG_mlocked);
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#ifdef CONFIG_MEMORY_FAILURE
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u |= kpf_copy_bit(k, KPF_HWPOISON, PG_hwpoison);
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#endif
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#ifdef CONFIG_ARCH_USES_PG_UNCACHED
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u |= kpf_copy_bit(k, KPF_UNCACHED, PG_uncached);
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#endif
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u |= kpf_copy_bit(k, KPF_RESERVED, PG_reserved);
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u |= kpf_copy_bit(k, KPF_MAPPEDTODISK, PG_mappedtodisk);
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u |= kpf_copy_bit(k, KPF_PRIVATE, PG_private);
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u |= kpf_copy_bit(k, KPF_PRIVATE_2, PG_private_2);
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u |= kpf_copy_bit(k, KPF_OWNER_PRIVATE, PG_owner_priv_1);
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u |= kpf_copy_bit(k, KPF_ARCH, PG_arch_1);
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return u;
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};
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static ssize_t kpageflags_read(struct file *file, char __user *buf,
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size_t count, loff_t *ppos)
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{
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u64 __user *out = (u64 __user *)buf;
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struct page *ppage;
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unsigned long src = *ppos;
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unsigned long pfn;
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ssize_t ret = 0;
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pfn = src / KPMSIZE;
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count = min_t(unsigned long, count, (max_pfn * KPMSIZE) - src);
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if (src & KPMMASK || count & KPMMASK)
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return -EINVAL;
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while (count > 0) {
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if (pfn_valid(pfn))
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ppage = pfn_to_page(pfn);
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else
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ppage = NULL;
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if (put_user(stable_page_flags(ppage), out)) {
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ret = -EFAULT;
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break;
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}
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pfn++;
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out++;
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count -= KPMSIZE;
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}
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*ppos += (char __user *)out - buf;
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if (!ret)
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ret = (char __user *)out - buf;
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return ret;
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}
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static const struct file_operations proc_kpageflags_operations = {
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.llseek = mem_lseek,
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.read = kpageflags_read,
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};
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static int __init proc_page_init(void)
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{
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proc_create("kpagecount", S_IRUSR, NULL, &proc_kpagecount_operations);
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proc_create("kpageflags", S_IRUSR, NULL, &proc_kpageflags_operations);
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return 0;
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}
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module_init(proc_page_init);
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