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The Committed_AS field can underflow in certain situations: > # while true; do cat /proc/meminfo | grep _AS; sleep 1; done | uniq -c > 1 Committed_AS: 18446744073709323392 kB > 11 Committed_AS: 18446744073709455488 kB > 6 Committed_AS: 35136 kB > 5 Committed_AS: 18446744073709454400 kB > 7 Committed_AS: 35904 kB > 3 Committed_AS: 18446744073709453248 kB > 2 Committed_AS: 34752 kB > 9 Committed_AS: 18446744073709453248 kB > 8 Committed_AS: 34752 kB > 3 Committed_AS: 18446744073709320960 kB > 7 Committed_AS: 18446744073709454080 kB > 3 Committed_AS: 18446744073709320960 kB > 5 Committed_AS: 18446744073709454080 kB > 6 Committed_AS: 18446744073709320960 kB Because NR_CPUS can be greater than 1000 and meminfo_proc_show() does not check for underflow. But NR_CPUS proportional isn't good calculation. In general, possibility of lock contention is proportional to the number of online cpus, not theorical maximum cpus (NR_CPUS). The current kernel has generic percpu-counter stuff. using it is right way. it makes code simplify and percpu_counter_read_positive() don't make underflow issue. Reported-by: Dave Hansen <dave@linux.vnet.ibm.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Cc: Eric B Munson <ebmunson@us.ibm.com> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Christoph Lameter <cl@linux-foundation.org> Cc: <stable@kernel.org> [All kernel versions] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
175 lines
4.3 KiB
C
175 lines
4.3 KiB
C
#include <linux/fs.h>
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#include <linux/hugetlb.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/mm.h>
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#include <linux/mman.h>
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#include <linux/mmzone.h>
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#include <linux/proc_fs.h>
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#include <linux/quicklist.h>
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#include <linux/seq_file.h>
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#include <linux/swap.h>
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#include <linux/vmstat.h>
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#include <asm/atomic.h>
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#include <asm/page.h>
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#include <asm/pgtable.h>
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#include "internal.h"
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void __attribute__((weak)) arch_report_meminfo(struct seq_file *m)
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{
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}
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static int meminfo_proc_show(struct seq_file *m, void *v)
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{
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struct sysinfo i;
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unsigned long committed;
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unsigned long allowed;
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struct vmalloc_info vmi;
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long cached;
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unsigned long pages[NR_LRU_LISTS];
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int lru;
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/*
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* display in kilobytes.
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*/
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#define K(x) ((x) << (PAGE_SHIFT - 10))
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si_meminfo(&i);
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si_swapinfo(&i);
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committed = percpu_counter_read_positive(&vm_committed_as);
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allowed = ((totalram_pages - hugetlb_total_pages())
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* sysctl_overcommit_ratio / 100) + total_swap_pages;
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cached = global_page_state(NR_FILE_PAGES) -
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total_swapcache_pages - i.bufferram;
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if (cached < 0)
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cached = 0;
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get_vmalloc_info(&vmi);
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for (lru = LRU_BASE; lru < NR_LRU_LISTS; lru++)
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pages[lru] = global_page_state(NR_LRU_BASE + lru);
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/*
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* Tagged format, for easy grepping and expansion.
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*/
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seq_printf(m,
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"MemTotal: %8lu kB\n"
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"MemFree: %8lu kB\n"
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"Buffers: %8lu kB\n"
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"Cached: %8lu kB\n"
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"SwapCached: %8lu kB\n"
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"Active: %8lu kB\n"
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"Inactive: %8lu kB\n"
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"Active(anon): %8lu kB\n"
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"Inactive(anon): %8lu kB\n"
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"Active(file): %8lu kB\n"
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"Inactive(file): %8lu kB\n"
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#ifdef CONFIG_UNEVICTABLE_LRU
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"Unevictable: %8lu kB\n"
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"Mlocked: %8lu kB\n"
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#endif
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#ifdef CONFIG_HIGHMEM
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"HighTotal: %8lu kB\n"
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"HighFree: %8lu kB\n"
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"LowTotal: %8lu kB\n"
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"LowFree: %8lu kB\n"
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#endif
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#ifndef CONFIG_MMU
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"MmapCopy: %8lu kB\n"
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#endif
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"SwapTotal: %8lu kB\n"
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"SwapFree: %8lu kB\n"
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"Dirty: %8lu kB\n"
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"Writeback: %8lu kB\n"
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"AnonPages: %8lu kB\n"
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"Mapped: %8lu kB\n"
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"Slab: %8lu kB\n"
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"SReclaimable: %8lu kB\n"
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"SUnreclaim: %8lu kB\n"
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"PageTables: %8lu kB\n"
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#ifdef CONFIG_QUICKLIST
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"Quicklists: %8lu kB\n"
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#endif
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"NFS_Unstable: %8lu kB\n"
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"Bounce: %8lu kB\n"
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"WritebackTmp: %8lu kB\n"
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"CommitLimit: %8lu kB\n"
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"Committed_AS: %8lu kB\n"
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"VmallocTotal: %8lu kB\n"
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"VmallocUsed: %8lu kB\n"
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"VmallocChunk: %8lu kB\n",
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K(i.totalram),
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K(i.freeram),
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K(i.bufferram),
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K(cached),
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K(total_swapcache_pages),
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K(pages[LRU_ACTIVE_ANON] + pages[LRU_ACTIVE_FILE]),
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K(pages[LRU_INACTIVE_ANON] + pages[LRU_INACTIVE_FILE]),
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K(pages[LRU_ACTIVE_ANON]),
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K(pages[LRU_INACTIVE_ANON]),
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K(pages[LRU_ACTIVE_FILE]),
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K(pages[LRU_INACTIVE_FILE]),
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#ifdef CONFIG_UNEVICTABLE_LRU
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K(pages[LRU_UNEVICTABLE]),
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K(global_page_state(NR_MLOCK)),
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#endif
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#ifdef CONFIG_HIGHMEM
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K(i.totalhigh),
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K(i.freehigh),
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K(i.totalram-i.totalhigh),
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K(i.freeram-i.freehigh),
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#endif
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#ifndef CONFIG_MMU
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K((unsigned long) atomic_long_read(&mmap_pages_allocated)),
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#endif
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K(i.totalswap),
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K(i.freeswap),
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K(global_page_state(NR_FILE_DIRTY)),
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K(global_page_state(NR_WRITEBACK)),
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K(global_page_state(NR_ANON_PAGES)),
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K(global_page_state(NR_FILE_MAPPED)),
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K(global_page_state(NR_SLAB_RECLAIMABLE) +
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global_page_state(NR_SLAB_UNRECLAIMABLE)),
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K(global_page_state(NR_SLAB_RECLAIMABLE)),
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K(global_page_state(NR_SLAB_UNRECLAIMABLE)),
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K(global_page_state(NR_PAGETABLE)),
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#ifdef CONFIG_QUICKLIST
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K(quicklist_total_size()),
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#endif
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K(global_page_state(NR_UNSTABLE_NFS)),
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K(global_page_state(NR_BOUNCE)),
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K(global_page_state(NR_WRITEBACK_TEMP)),
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K(allowed),
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K(committed),
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(unsigned long)VMALLOC_TOTAL >> 10,
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vmi.used >> 10,
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vmi.largest_chunk >> 10
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);
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hugetlb_report_meminfo(m);
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arch_report_meminfo(m);
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return 0;
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#undef K
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}
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static int meminfo_proc_open(struct inode *inode, struct file *file)
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{
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return single_open(file, meminfo_proc_show, NULL);
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}
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static const struct file_operations meminfo_proc_fops = {
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.open = meminfo_proc_open,
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.read = seq_read,
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.llseek = seq_lseek,
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.release = single_release,
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};
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static int __init proc_meminfo_init(void)
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{
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proc_create("meminfo", 0, NULL, &meminfo_proc_fops);
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return 0;
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}
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module_init(proc_meminfo_init);
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