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SubjectRe: [PATCH 2/2] hugetlb reservations: fix hugetlb MAP_PRIVATE reservations across vma splits
Typical. I spotted this after I pushed send.....

> <SNIP>

> @@ -266,14 +326,19 @@ static void decrement_hugepage_resv_vma(struct hstate *h,
> * private mappings.
> */
> if (is_vma_resv_set(vma, HPAGE_RESV_OWNER)) {
> - unsigned long flags, reserve;
> + unsigned long idx = vma_pagecache_offset(h,
> + vma, address);
> + struct resv_map *reservations = vma_resv_map(vma);
> +
> h->resv_huge_pages--;
> - flags = (unsigned long)vma->vm_private_data &
> - HPAGE_RESV_MASK;
> - reserve = (unsigned long)vma->vm_private_data - 1;
> - vma->vm_private_data = (void *)(reserve | flags);
> +
> + /* Mark this page used in the map. */
> + if (region_chg(&reservations->regions, idx, idx + 1) < 0)
> + return -1;
> + region_add(&reservations->regions, idx, idx + 1);
> }

decrement_hugepage_resv_vma() is called with hugetlb_lock held and region_chg
calls kmalloc(GFP_KERNEL). Hence it's possible we would sleep with that
spinlock held which is a bit uncool. The allocation needs to happen outside
the lock. Right?

> <SNIP>

--
Mel Gorman


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