Re: [PATCH v8 00/37] mm/virtio: skip redundant zeroing of host-zeroed pages

[Miaohe Lin]

On 2026/5/21 22:09, Michael S. Tsirkin wrote:
> On Wed, May 20, 2026 at 06:20:13PM -0400, Michael S. Tsirkin wrote:
>> When a guest reports free pages to the hypervisor via virtio-balloon's
>> free page reporting, the host typically zeros those pages when reclaiming
>> their backing memory (e.g., via MADV_DONTNEED on anonymous mappings).
>> When the guest later reallocates those pages, the kernel zeros them
>> again, redundantly.
> 
> FYI Sashiko reported a couple of issues. Mostly false positives but
> I tweaked commit log to make it clearer. But also a couple of
> real issues. So far I have this diff on top:
> 
> --->
> 
> Changes from v8 to v9 candidate (code only):
> 
> 1. mm/mempolicy.c (patch 1: mm: mempolicy: fix interleave index calculation)
>    Combine vm_pgoff and VMA offset into a single expression before
>    shifting, fixing carry loss for file-backed VMAs with unaligned
>    vm_pgoff.
> 
> 2. mm/memory-failure.c (patch 2: mm: memory-failure: serialize TestSetPageHWPoison with zone->lock)
>    Wrap ClearPageHWPoison in retry path with zone->lock too.

It seems TestClearPageHWPoison and SetPageHWPoison are missing. Should we serialize them with zone->lock too?

Thanks.
.