Revision 475049809977bf3975d78f2d2fd992e19ce2d59e authored by Roel Kluin on 10 March 2009, 19:55:45 UTC, committed by Linus Torvalds on 10 March 2009, 22:55:10 UTC
get_nid_for_pfn() returns int Presumably the (nid < 0) case has never happened. We do know that it is happening on one system while creating a symlink for a memory section so it should also happen on the same system if unregister_mem_sect_under_nodes() were called to remove the same symlink. The test was actually added in response to a problem with an earlier version reported by Yasunori Goto where one or more of the leading pages of a memory section on the 2nd node of one of his systems was uninitialized because I believe they coincided with a memory hole. That earlier version did not ignore uninitialized pages and determined the nid by considering only the 1st page of each memory section. This caused the symlink to the 1st memory section on the 2nd node to be incorrectly created in /sys/devices/system/node/node0 instead of /sys/devices/system/node/node1. The problem was fixed by adding the test to skip over uninitialized pages. I suspect we have not seen any reports of the non-removal of a symlink due to the incorrect declaration of the nid variable in unregister_mem_sect_under_nodes() because - systems where a memory section could have an uninitialized range of leading pages are probably rare. - memory remove is probably not done very frequently on the systems that are capable of demonstrating the problem. - lingering symlink(s) that should have been removed may have simply gone unnoticed. [garyhade@us.ibm.com: wrote changelog] Signed-off-by: Roel Kluin <roel.kluin@gmail.com> Cc: Gary Hade <garyhade@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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raid6algos.c
/* -*- linux-c -*- ------------------------------------------------------- *
*
* Copyright 2002 H. Peter Anvin - All Rights Reserved
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, Inc., 53 Temple Place Ste 330,
* Bostom MA 02111-1307, USA; either version 2 of the License, or
* (at your option) any later version; incorporated herein by reference.
*
* ----------------------------------------------------------------------- */
/*
* raid6algos.c
*
* Algorithm list and algorithm selection for RAID-6
*/
#include "raid6.h"
#ifndef __KERNEL__
#include <sys/mman.h>
#include <stdio.h>
#endif
struct raid6_calls raid6_call;
/* Various routine sets */
extern const struct raid6_calls raid6_intx1;
extern const struct raid6_calls raid6_intx2;
extern const struct raid6_calls raid6_intx4;
extern const struct raid6_calls raid6_intx8;
extern const struct raid6_calls raid6_intx16;
extern const struct raid6_calls raid6_intx32;
extern const struct raid6_calls raid6_mmxx1;
extern const struct raid6_calls raid6_mmxx2;
extern const struct raid6_calls raid6_sse1x1;
extern const struct raid6_calls raid6_sse1x2;
extern const struct raid6_calls raid6_sse2x1;
extern const struct raid6_calls raid6_sse2x2;
extern const struct raid6_calls raid6_sse2x4;
extern const struct raid6_calls raid6_altivec1;
extern const struct raid6_calls raid6_altivec2;
extern const struct raid6_calls raid6_altivec4;
extern const struct raid6_calls raid6_altivec8;
const struct raid6_calls * const raid6_algos[] = {
&raid6_intx1,
&raid6_intx2,
&raid6_intx4,
&raid6_intx8,
#if defined(__ia64__)
&raid6_intx16,
&raid6_intx32,
#endif
#if defined(__i386__) && !defined(__arch_um__)
&raid6_mmxx1,
&raid6_mmxx2,
&raid6_sse1x1,
&raid6_sse1x2,
&raid6_sse2x1,
&raid6_sse2x2,
#endif
#if defined(__x86_64__) && !defined(__arch_um__)
&raid6_sse2x1,
&raid6_sse2x2,
&raid6_sse2x4,
#endif
#ifdef CONFIG_ALTIVEC
&raid6_altivec1,
&raid6_altivec2,
&raid6_altivec4,
&raid6_altivec8,
#endif
NULL
};
#ifdef __KERNEL__
#define RAID6_TIME_JIFFIES_LG2 4
#else
/* Need more time to be stable in userspace */
#define RAID6_TIME_JIFFIES_LG2 9
#endif
/* Try to pick the best algorithm */
/* This code uses the gfmul table as convenient data set to abuse */
int __init raid6_select_algo(void)
{
const struct raid6_calls * const * algo;
const struct raid6_calls * best;
char *syndromes;
void *dptrs[(65536/PAGE_SIZE)+2];
int i, disks;
unsigned long perf, bestperf;
int bestprefer;
unsigned long j0, j1;
disks = (65536/PAGE_SIZE)+2;
for ( i = 0 ; i < disks-2 ; i++ ) {
dptrs[i] = ((char *)raid6_gfmul) + PAGE_SIZE*i;
}
/* Normal code - use a 2-page allocation to avoid D$ conflict */
syndromes = (void *) __get_free_pages(GFP_KERNEL, 1);
if ( !syndromes ) {
printk("raid6: Yikes! No memory available.\n");
return -ENOMEM;
}
dptrs[disks-2] = syndromes;
dptrs[disks-1] = syndromes + PAGE_SIZE;
bestperf = 0; bestprefer = 0; best = NULL;
for ( algo = raid6_algos ; *algo ; algo++ ) {
if ( !(*algo)->valid || (*algo)->valid() ) {
perf = 0;
preempt_disable();
j0 = jiffies;
while ( (j1 = jiffies) == j0 )
cpu_relax();
while (time_before(jiffies,
j1 + (1<<RAID6_TIME_JIFFIES_LG2))) {
(*algo)->gen_syndrome(disks, PAGE_SIZE, dptrs);
perf++;
}
preempt_enable();
if ( (*algo)->prefer > bestprefer ||
((*algo)->prefer == bestprefer &&
perf > bestperf) ) {
best = *algo;
bestprefer = best->prefer;
bestperf = perf;
}
printk("raid6: %-8s %5ld MB/s\n", (*algo)->name,
(perf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
}
}
if (best) {
printk("raid6: using algorithm %s (%ld MB/s)\n",
best->name,
(bestperf*HZ) >> (20-16+RAID6_TIME_JIFFIES_LG2));
raid6_call = *best;
} else
printk("raid6: Yikes! No algorithm found!\n");
free_pages((unsigned long)syndromes, 1);
return best ? 0 : -EINVAL;
}
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