Re: Re: [Oops] i386 mm/slab.c (cache_flusharray)

[pinotj]

Sorry to be late,

>De: Linus Torvalds <torvalds@xxxxxxxx>
[...]
>> Summary: Oops reproductible when heavy load, bug in mm/slab.c
>
>Do you have CONFIG_PREEMPT on, and if so, does it go away if you compile without PREEMPT? We have at least one other bug that seems to be dependent on CONFIG_PREEMPT

I compiled without PREEMPT and first it seemed good. I could compile again a kernel without problem.
But later, I got the same oops when doing something else
(like `./configure` in parallele with a `make install` on other tty) so CONFIG_PREEMPT doesn't seem to be the cause, unfortunately, but a parameter than can affect the probability of getting the oops.

>De: Manfred Spraul <manfred@xxxxxxxxxxxxxxxx>
[...]
>>slab: double free detected in cache 'buffer_head', objp cc3f9798, objnr 26, slabp cc3f9000, s_mem cc3f9180 bufctl f7ffffff.  
>>
>Good.
>
>+#define BUFCTL_END	0xfeffFFFF
>+#define BUFCTL_FREE	0xf7ffFFFE
>+#define	SLAB_LIMIT	0xf0ffFFFD

This seems to solve the problem, no oops during kernel compilation. Unfortunately, considering what I wrote just above, I'm not so sure it's really solved. Now I will use the 2.6.0-test10 and make again tests (alone, with this patch, with PREEMPT_CONFIG=n)

>f7ffffff is not a valid value, slab never writes that into a bufctl. 
>Someone did a ++ or "|= 1", or a hw bug.
>I think the Athlon cpus have ECC for the L2 cache - could you check in 
>the bios that ECC checking is enabled?

Well, cheap mainboard (VIA K7S5A) with cheap BIOS. I can only {en,dis}able cache L1/L2, nothing about ECC. DRAM is set to safe.
But as I said, I got no problem with 2.6.0-test9 vanilla. I compiled all my LFS/BLFS with it during several days.
I even use it these days as rescue kernel to compile the others.

Thanks for your help,

Jerome Pinot

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