Thread (27 messages) 27 messages, 6 authors, 2007-10-29

Re: Apparent kernel bug with GDB on ppc405

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2007-10-27 01:36:40

On Fri, 2007-10-26 at 15:41 -0500, Josh Boyer wrote:
On Fri, 26 Oct 2007 11:51:22 +1000
Benjamin Herrenschmidt [off-list ref] wrote:
quoted
On Wed, 2007-10-24 at 18:41 -0400, Daniel Jacobowitz wrote:
quoted
On Wed, Oct 24, 2007 at 05:32:50PM -0500, Matt Mackall wrote:
quoted
Not completely implausible, but a) why isn't this seen on basically
every machine with software TLB? b) why does -local- GDB, which is
presumably doing much less work than gdbserver + network stack, not fail?
You said it yourself.  Local gdb does more work -> blows through more
TLB entries.

I can't answer you about the other half, but I'm pretty sure TLB
invalidation is already supposed to be happening... somewhere.
Yes. do_wp_page() -> ptep_clear_flush() -> flush_tlb_page()
Aren't there cases in do_wp_page that don't call ptep_clear_flush?
Seems anonymous pages, and possibly shared writeable pages skip that
step if reuse is true.
Nah, if that was broken, everybody would be in bad shape. I think I know
what's up, see my other email.

Cheers,
Ben.
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