Fix a boundary case error in vm_reserv_alloc_contig(): If a reservation
isn't being allocated for the last of the requested pages, because a reservation won't fit in the gap between allocated pages, then the reservation structure shouldn't be initialized. While I'm here, improve the nearby comments. Reported by: jeff, pho MFC after: 1 week Sponsored by: EMC / Isilon Storage Division
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=271351
@ -364,7 +364,7 @@ vm_reserv_populate(vm_reserv_t rv, int index)
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/*
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* Allocates a contiguous set of physical pages of the given size "npages"
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* from an existing or newly-created reservation. All of the physical pages
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* from existing or newly created reservations. All of the physical pages
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* must be at or above the given physical address "low" and below the given
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* physical address "high". The given value "alignment" determines the
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* alignment of the first physical page in the set. If the given value
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@ -436,8 +436,8 @@ vm_reserv_alloc_contig(vm_object_t object, vm_pindex_t pindex, u_long npages,
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/*
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* Could at least one reservation fit between the first index to the
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* left that can be used and the first index to the right that cannot
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* be used?
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* left that can be used ("leftcap") and the first index to the right
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* that cannot be used ("rightcap")?
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*/
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first = pindex - VM_RESERV_INDEX(object, pindex);
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if (mpred != NULL) {
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@ -459,6 +459,13 @@ vm_reserv_alloc_contig(vm_object_t object, vm_pindex_t pindex, u_long npages,
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if (first + maxpages > rightcap) {
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if (maxpages == VM_LEVEL_0_NPAGES)
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return (NULL);
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/*
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* At least one reservation will fit between "leftcap"
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* and "rightcap". However, a reservation for the
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* last of the requested pages will not fit. Reduce
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* the size of the upcoming allocation accordingly.
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*/
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allocpages = minpages;
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}
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}
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@ -482,16 +489,23 @@ vm_reserv_alloc_contig(vm_object_t object, vm_pindex_t pindex, u_long npages,
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}
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/*
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* Allocate and populate the new reservations. The alignment and
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* boundary specified for this allocation may be different from the
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* alignment and boundary specified for the requested pages. For
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* instance, the specified index may not be the first page within the
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* first new reservation.
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* Allocate the physical pages. The alignment and boundary specified
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* for this allocation may be different from the alignment and
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* boundary specified for the requested pages. For instance, the
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* specified index may not be the first page within the first new
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* reservation.
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*/
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m = vm_phys_alloc_contig(allocpages, low, high, ulmax(alignment,
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VM_LEVEL_0_SIZE), boundary > VM_LEVEL_0_SIZE ? boundary : 0);
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if (m == NULL)
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return (NULL);
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/*
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* The allocated physical pages always begin at a reservation
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* boundary, but they do not always end at a reservation boundary.
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* Initialize every reservation that is completely covered by the
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* allocated physical pages.
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*/
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m_ret = NULL;
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index = VM_RESERV_INDEX(object, pindex);
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do {
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@ -525,7 +539,7 @@ vm_reserv_alloc_contig(vm_object_t object, vm_pindex_t pindex, u_long npages,
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m += VM_LEVEL_0_NPAGES;
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first += VM_LEVEL_0_NPAGES;
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allocpages -= VM_LEVEL_0_NPAGES;
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} while (allocpages > 0);
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} while (allocpages >= VM_LEVEL_0_NPAGES);
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return (m_ret);
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/*
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