Messages in this thread | | | Date | Fri, 03 Feb 2006 02:44:52 +0200 | From | Avi Kivity <> | Subject | Re: discriminate single bit error hardware failure from slab corruption. |
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Dave Jones wrote:
>In the case where we detect a single bit has been flipped, we spew >the usual slab corruption message, which users instantly think >is a kernel bug. In a lot of cases, single bit errors are >down to bad memory, or other hardware failure. > >This patch adds an extra line to the slab debug messages in those >cases, in the hope that users will try memtest before they report a bug. > >000: 6b 6b 6b 6b 6a 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b 6b >Single bit error detected. Possibly bad RAM. Please run memtest86. > >Signed-off-by: Dave Jones <davej@redhat.com> > >--- linux-2.6.15/mm/slab.c~ 2006-01-09 13:25:17.000000000 -0500 >+++ linux-2.6.15/mm/slab.c 2006-01-09 13:26:01.000000000 -0500 >@@ -1313,8 +1313,11 @@ static void poison_obj(kmem_cache_t *cac > static void dump_line(char *data, int offset, int limit) > { > int i; >+ unsigned char total=0; > printk(KERN_ERR "%03x:", offset); > for (i = 0; i < limit; i++) { >+ if (data[offset+i] != POISON_FREE) >+ total += data[offset+i]; > > how about
total += hweight8(data[offset+i] ^ POISON_FREE);
> printk(" %02x", (unsigned char)data[offset + i]); > } > printk("\n"); >@@ -1019,6 +1023,18 @@ static void dump_line(char *data, int of > } > } > printk("\n"); >+ switch (total) { >+ case 0x36: >+ case 0x6a: >+ case 0x6f: >+ case 0x81: >+ case 0xac: >+ case 0xd3: >+ case 0xd5: >+ case 0xea: >+ printk (KERN_ERR "Single bit error detected. Possibly bad RAM. Please run memtest86.\n"); >+ return; >+ } > > and a
if (total == 1) printk(...);
here? it seems more readable and more correct as well.
> } > #endif > > >
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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