Re: [Bug 8040] Hang before INIT when CONFIG_HIGHMEM4G=y [FixCONFIG_COMPAT_VDSO] <- Bad

[Andrew Morton]

> On Wed, 14 Mar 2007 17:52:01 +0000 (UTC) Leroy van Logchem <leroy.vanlogchem@xxxxxxxxxx> wrote:
> Leroy van Logchem <leroy.vanlogchem <at> wldelft.nl> writes:
> 
> > 
> > > > None whatsoever.  Three people are reporting this and it's a drop-dead
> > > > showstopper for a 2.6.21 release so we just have to wait until someone
> > > > wakes up and thinks about it.
> > 
> > The topic should be "when CONFIG_HIGHMEM64G=y" imo.
> > 
> > I'll try to do my first bi-sect today.

Thanks.   Please always do reply-to-all.  Cc's restored (and added..)

> Bisecting went well, after 13 compiles this commit was found:
> 
> a1f3bb9ae4497a2ed3eac773fd7798ac33a0371f is first bad commit
> commit a1f3bb9ae4497a2ed3eac773fd7798ac33a0371f
> Author: Roland McGrath <roland@xxxxxxxxxx>
> Date:   Fri Jan 26 00:56:46 2007 -0800
> 
>     [PATCH] Fix CONFIG_COMPAT_VDSO
>     
>     I wouldn't mind if CONFIG_COMPAT_VDSO went away entirely.  But if it's there,
>     it should work properly.  Currently it's quite haphazard: both real vma and
>     fixmap are mapped, both are put in the two different AT_* slots, sysenter
>     returns to the vma address rather than the fixmap address, and core dumps yet
>     are another story.
>     
>     This patch makes CONFIG_COMPAT_VDSO disable the real vma and use the fixmap
>     area consistently.  This makes it actually compatible with what the old vdso
>     implementation did.
>     
>     Signed-off-by: Roland McGrath <roland@xxxxxxxxxx>
>     Cc: Ingo Molnar <mingo@xxxxxxx>
>     Cc: Paul Mackerras <paulus@xxxxxxxxx>
>     Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
>     Cc: Andi Kleen <ak@xxxxxxx>
>     Signed-off-by: Andrew Morton <akpm@xxxxxxxx>
>     Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> 
> :040000 040000 802ab3366a651ecba28c8677fa84a9f7c506392b
> f44adc4dcdab733e5965b68ccd0d643f0a550a80 M      arch
> :040000 040000 be1e217152d8b3fcd05f09aa2b3f4f9dcb8208aa
> 46cc86427e861350dd3fef9469474c55119f27ce M      include
> 
> I had both CONFIG_COMPAT_VDSO=y and CONFIG_HIGHMEM64G=y configured.
> Using a 4GB Supermicro 7044 SMP dual Xeon. Details upon request.
> 
> --
> Leroy
> 
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