On Wed, Aug 10, 2022 at 07:49:00PM -0700, Ira wrote:
> From: Ira Weiny <ira.weiny@intel.com>
Any feedback on this series? Or has Rik's patches been accepted instead?
Ira
>
> Changes from RFC:
> Drop patch 1 as I misunderstood the code and it is not needed for this
> use case
> Combine patch 2 and 5 into a patch 3 which stores the CPU only for page
> faults
>
> Rik reported that the knowledge of which CPU's are seeing faults can help in
> determining which CPUs are failing in a large data center.[1]
>
> Storing the CPU at exception entry time allows this print to report the CPU
> which actually took the exception. This still may not be the CPU which is
> failing but it should be closer.
>
> Dave and Boris recognized that the auxiliary pt_regs work I did for the PKS
> series could help to store this value and avoid passing the CPU throughout the
> fault handler call stack.
>
> The patches I sent for RFC had a lot more overhead than is needed to report the
> CPU in a page fault.[2] After the discussions the generic save/restore of the
> auxiliary pt_regs is overkill for the current use case. Skip that overhead and
> only store the CPU in the page fault path.
>
> [1] https://lore.kernel.org/all/20220805101644.2e674553@imladris.surriel.com/
> [2] https://lore.kernel.org/lkml/20220805173009.3128098-1-ira.weiny@intel.com/
>
> Ira Weiny (2):
> x86/entry: Add auxiliary pt_regs space
> x86/mm: Store CPU info on exception entry
>
> Rik van Riel (1):
> x86,mm: print likely CPU at segfault time
>
> arch/x86/Kconfig | 4 ++++
> arch/x86/entry/calling.h | 19 +++++++++++++++++++
> arch/x86/entry/entry_64.S | 22 ++++++++++++++++++++++
> arch/x86/entry/entry_64_compat.S | 6 ++++++
> arch/x86/include/asm/ptrace.h | 19 +++++++++++++++++++
> arch/x86/kernel/asm-offsets_64.c | 15 +++++++++++++++
> arch/x86/kernel/head_64.S | 6 ++++++
> arch/x86/mm/fault.c | 18 ++++++++++++++++++
> 8 files changed, 109 insertions(+)
>
>
> base-commit: d4252071b97d2027d246f6a82cbee4d52f618b47
> --
> 2.35.3
>