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SubjectRe: [PATCH 5/9] HWPoison: add memory_failure_queue()

* Huang Ying <ying.huang@intel.com> wrote:

> memory_failure() is the entry point for HWPoison memory error
> recovery. It must be called in process context. But commonly
> hardware memory errors are notified via MCE or NMI, so some delayed
> execution mechanism must be used. In MCE handler, a work queue + ring
> buffer mechanism is used.
>
> In addition to MCE, now APEI (ACPI Platform Error Interface) GHES
> (Generic Hardware Error Source) can be used to report memory errors
> too. To add support to APEI GHES memory recovery, a mechanism similar
> to that of MCE is implemented. memory_failure_queue() is the new
> entry point that can be called in IRQ context. The next step is to
> make MCE handler uses this interface too.
>
> Signed-off-by: Huang Ying <ying.huang@intel.com>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Wu Fengguang <fengguang.wu@intel.com>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> include/linux/mm.h | 1
> mm/memory-failure.c | 92 ++++++++++++++++++++++++++++++++++++++++++++++++++++
> 2 files changed, 93 insertions(+)

I have to say i disagree with how this is designed and how this is exposed to
user-space - and i pointed this out before.

It's up to Len whether you muck up drivers/acpi/ but here you are patching mm/
again ...

I just had a quick look into the current affairs of mm/memory-inject.c and it
has become an *even* nastier collection of hacks since the last time i
commented on its uglies.

Special hack upon special hack, totally disorganized code, special-purpose,
partly ioctl driven opaque information extraction to user-space using the
erst-dbg device interface. We have all the maintenance overhead and little of
the gains from hw error event features...

In this patch you add:

+struct memory_failure_entry {
+ unsigned long pfn;
+ int trapno;
+ int flags;
+};
Instead of exposing this event to other users who might be interested in these
events - such as the RAS daemon under development by Boris.

We have a proper framework (ring-buffer, NMI execution, etc.) for reporting
events, why are you not using (and extending) it instead of creating this nasty
looking, isolated, ACPI specific low level feature?

Thanks,

Ingo


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