Bug#569797: misaligned signal stack on sparc

2010-02-14 Thread Bernhard R. Link
Package: linux-image-2.6.32-2-sparc64-smp
Version: 2.6.32-8
Severity: serious

On my sid sparc box I can reproducibly cause a shell getting
in a state where the kernel soft-locks and one cpu is only
occupied py this process. kill -KILL does not work, sync does
not work, restarting the computer needs reboot -n -f and so on.

I think this is due to some misalignment of signal stacks, as
described in
http://marc.info/?l=linux-sparcm=126576299426902w=2
(at least the hanging cpu hangs in the area this patch touches and
the process seems to be hanging in some fault handler occouring in
a fault handler occouring in some signal stuff as far as I can tell,
my sparc assembler skills are quite limited).

Note that the patch given in the mail has still a typo described in
http://marc.info/?l=linux-sparcm=126592005119857w=2
See also
http://marc.info/?l=linux-sparcm=126592110921290w=2
(Though I do not know if this fix for the patch is needed for 32 bit
sparc kernels Debian afaik no longer has or for 32 bit user space,
but I guess adding both is safest in any case).

Hochachtungsvoll,
Bernhard R. Link

This bug also effects (at least) 2.6.32-3 and 2.6.32-5, but I have no
idea how to tell this the bts as the binary package name changed.



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Bug#569797: misaligned signal stack on sparc

2010-02-14 Thread Ben Hutchings
On Sun, 2010-02-14 at 12:36 +0100, Bernhard R. Link wrote:
 Package: linux-image-2.6.32-2-sparc64-smp
 Version: 2.6.32-8
 Severity: serious
 
 On my sid sparc box I can reproducibly cause a shell getting
 in a state where the kernel soft-locks and one cpu is only
 occupied py this process. kill -KILL does not work, sync does
 not work, restarting the computer needs reboot -n -f and so on.
 
 I think this is due to some misalignment of signal stacks, as
 described in
 http://marc.info/?l=linux-sparcm=126576299426902w=2
 (at least the hanging cpu hangs in the area this patch touches and
 the process seems to be hanging in some fault handler occouring in
 a fault handler occouring in some signal stuff as far as I can tell,
 my sparc assembler skills are quite limited).
 
 Note that the patch given in the mail has still a typo described in
 http://marc.info/?l=linux-sparcm=126592005119857w=2
 See also
 http://marc.info/?l=linux-sparcm=126592110921290w=2
 (Though I do not know if this fix for the patch is needed for 32 bit
 sparc kernels Debian afaik no longer has or for 32 bit user space,
 but I guess adding both is safest in any case).

I've forwarded these changes to sta...@kernel.org for review.  Thank you
for finding them.

 Hochachtungsvoll,
   Bernhard R. Link
 
 This bug also effects (at least) 2.6.32-3 and 2.6.32-5, but I have no
 idea how to tell this the bts as the binary package name changed.

You should report bugs against the source package linux-2.6, and the bug
script ensures that this happens.  Please use reportbug in future.

Ben.

-- 
Ben Hutchings
It is easier to change the specification to fit the program than vice versa.


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