On 28.01.2026 13:03, Roger Pau Monne wrote:
> @@ -275,7 +339,18 @@ static void populate_physmap(struct memop_args *a)
> }
> else
> {
> - page = alloc_domheap_pages(d, a->extent_order, a->memflags);
> + unsigned int scrub_start = 0;
> + nodeid_t node =
> + (a->memflags & MEMF_exact_node) ?
> MEMF_get_node(a->memflags)
> + : NUMA_NO_NODE;
> +
> + page = get_stashed_allocation(d, a->extent_order, node,
> + &scrub_start);
> +
> + if ( !page )
> + page = alloc_domheap_pages(d, a->extent_order,
> + a->memflags | (d->creation_finished ? 0
> + :
> MEMF_no_scrub));
I fear there's a more basic issue here that so far we didn't pay attention to:
alloc_domheap_pages() is what invokes assign_page(), which in turn resets
->count_info for each of the pages. This reset includes setting PGC_allocated,
which ...
> @@ -286,6 +361,30 @@ static void populate_physmap(struct memop_args *a)
> goto out;
> }
>
> + if ( !d->creation_finished )
> + {
> + unsigned int dirty_cnt = 0;
> +
> + /* Check if there's anything to scrub. */
> + for ( j = scrub_start; j < (1U << a->extent_order); j++ )
> + {
> + if ( !test_and_clear_bit(_PGC_need_scrub,
> + &page[j].count_info) )
> + continue;
... means we will now scrub every page in the block, not just those which
weren't
scrubbed yet, and we end up clearing PGC_allocated. All because of
PGC_need_scrub
aliasing PGC_allocated. I wonder how this didn't end up screwing any testing you
surely will have done. Or maybe I'm completely off here?
Jan
