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vm_phys: fix seg->end test in alloc_seg_contig

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In vm_phys_alloc_seg_contig, in allocating multiple memory blocks for
a huge allocation, ensure that the end of the allocated range does not
exceed the upper segment limit.

Reorder a couple of checks to improve code layout.

Reviewed by:	alc
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D33870
This commit is contained in:
Doug Moore 2022-01-18 12:32:46 -06:00
parent da7fc5c33f
commit da92ecbc0d
1 changed files with 34 additions and 37 deletions
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71
sys/vm/vm_phys.c
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@ -1428,47 +1428,44 @@ vm_phys_alloc_seg_contig(struct vm_phys_seg *seg, u_long npages,
fl = (*seg->free_queues)[pind];
TAILQ_FOREACH(m_ret, &fl[oind].pl, listq) {
/*
* Is the size of this allocation request
* larger than the largest block size?
*/
if (order >= VM_NFREEORDER) {
/*
* Determine if a sufficient number of
* subsequent blocks to satisfy the
* allocation request are free.
*/
pa = VM_PAGE_TO_PHYS(m_ret);
pa_end = pa + size;
if (pa_end < pa)
continue;
for (;;) {
pa += 1 << (PAGE_SHIFT +
VM_NFREEORDER - 1);
if (pa >= pa_end ||
pa < seg->start ||
pa >= seg->end)
break;
m = &seg->first_page[atop(pa -
seg->start)];
if (m->order != VM_NFREEORDER -
1)
break;
}
/* If not, go to the next block. */
if (pa < pa_end)
continue;
}
/*
* Determine if the blocks are within the
* given range, satisfy the given alignment,
* and do not cross the given boundary.
* Determine if the address range starting at pa
* is within the given range, satisfies the
* given alignment, and does not cross the given
* boundary.
*/
pa = VM_PAGE_TO_PHYS(m_ret);
pa_end = pa + size;
if (pa >= low && pa_end <= high &&
vm_addr_ok(pa, size, alignment, boundary))
if (pa < low || pa_end > high ||
!vm_addr_ok(pa, size, alignment, boundary))
continue;
/*
* Is the size of this allocation request
* no more than the largest block size?
*/
if (order < VM_NFREEORDER)
goto done;
/*
* Determine if the address range is valid
* (without overflow in pa_end calculation)
* and fits within the segment.
*/
if (pa_end < pa || pa_end > seg->end)
continue;
/*
* Determine if a sufficient number of
* subsequent blocks to satisfy the
* allocation request are free.
*/
do {
pa += 1 <<
(PAGE_SHIFT + VM_NFREEORDER - 1);
if (pa >= pa_end)
goto done;
} while (VM_NFREEORDER - 1 == seg->first_page[
atop(pa - seg->start)].order);
}
}
}