On Fri, 2013-05-31 at 14:45 +0530, Aneesh Kumar K.V wrote:
quoted
The patch you are running on is what I'll send to Linus for 3.10 (+/-
cosmetics). Aneesh second patch is a much larger rework which will be
needed for THP but that will wait for 3.11. I'm happy for you to test it
but I first want to make sure it's solid with the 3.10 fix :-)
BTW. One concern I still have is that Hugh identified the bad commit
to be:
7e74c3921ad9610c0b49f28b8fc69f7480505841
"powerpc: Fix hpte_decode to use the correct decoding for page sizes".
However, you introduce the return on HPTE not found earlier, in
b1022fbd293564de91596b8775340cf41ad5214c
"powerpc: Decode the pte-lp-encoding bits correctly."
So while I'm still happy with the current band-aid for 3.10 and am
about to send it to Linus, the above *does* seem to indicate that
there is also something wrong with the "Fix hpte_decode..." commit,
which might not actually get the page size right...
Can you investigate ?
Cheers,
Ben.
Benjamin Herrenschmidt [off-list ref] writes:
On Fri, 2013-05-31 at 14:45 +0530, Aneesh Kumar K.V wrote:
quoted
quoted
The patch you are running on is what I'll send to Linus for 3.10 (+/-
cosmetics). Aneesh second patch is a much larger rework which will be
needed for THP but that will wait for 3.11. I'm happy for you to test it
but I first want to make sure it's solid with the 3.10 fix :-)
BTW. One concern I still have is that Hugh identified the bad commit
to be:
7e74c3921ad9610c0b49f28b8fc69f7480505841
"powerpc: Fix hpte_decode to use the correct decoding for page sizes".
However, you introduce the return on HPTE not found earlier, in
b1022fbd293564de91596b8775340cf41ad5214c
"powerpc: Decode the pte-lp-encoding bits correctly."
So while I'm still happy with the current band-aid for 3.10 and am
about to send it to Linus, the above *does* seem to indicate that
there is also something wrong with the "Fix hpte_decode..." commit,
which might not actually get the page size right...
Can you investigate ?
7e74c3921ad9610c0b49f28b8fc69f7480505841
"powerpc: Fix hpte_decode to use the correct decoding for page sizes"
changes should only impact hpte_decode. We don't change the details
of hpte_actual_psize at all in this patch. That means we should see a
difference only with kexec right ?.
Hugh,
Will you be able to double check whether
7e74c3921ad9610c0b49f28b8fc69f7480505841 is the bad commit. The one
before that is what we changed in the patch that fixed your problem.
-aneesh
On Sun, 2 Jun 2013, Aneesh Kumar K.V wrote:
Benjamin Herrenschmidt [off-list ref] writes:
quoted
On Fri, 2013-05-31 at 14:45 +0530, Aneesh Kumar K.V wrote:
quoted
quoted
The patch you are running on is what I'll send to Linus for 3.10 (+/-
cosmetics). Aneesh second patch is a much larger rework which will be
needed for THP but that will wait for 3.11. I'm happy for you to test it
but I first want to make sure it's solid with the 3.10 fix :-)
BTW. One concern I still have is that Hugh identified the bad commit
to be:
7e74c3921ad9610c0b49f28b8fc69f7480505841
"powerpc: Fix hpte_decode to use the correct decoding for page sizes".
However, you introduce the return on HPTE not found earlier, in
b1022fbd293564de91596b8775340cf41ad5214c
"powerpc: Decode the pte-lp-encoding bits correctly."
So while I'm still happy with the current band-aid for 3.10 and am
about to send it to Linus, the above *does* seem to indicate that
there is also something wrong with the "Fix hpte_decode..." commit,
which might not actually get the page size right...
Can you investigate ?
7e74c3921ad9610c0b49f28b8fc69f7480505841
"powerpc: Fix hpte_decode to use the correct decoding for page sizes"
changes should only impact hpte_decode. We don't change the details
of hpte_actual_psize at all in this patch. That means we should see a
difference only with kexec right ?.
Hugh,
Will you be able to double check whether
7e74c3921ad9610c0b49f28b8fc69f7480505841 is the bad commit. The one
before that is what we changed in the patch that fixed your problem.
You are absolutely right. I just set b1022fbd29 going, expecting
to answer you tomorrow: but got a Segmentation fault in 20 minutes
(quicker than ever seen before). It looks as if I was running some
other kernel for the last stage of my bisection: I can't see how that
came about, but it's not very interesting now - you got it right.
Prior to trying that, I had been running your second patch, 9f70fd8cfe,
and that tested out successfully for 50 hours before I stopped it.
Hugh