vm: Don't break vm reserv that can't meet align reqs
Function vm_reserv_test_contig has incorrectly used its alignment and boundary parameters to find a well-positioned range of empty pages in a reservation. Consequently, a reservation could be broken mistakenly when it was unable to provide a satisfactory set of pages. Rename the function, correct the errors, and add assertions to detect the error in case it appears again. Reviewed by: alc, markj MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D33344
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@ -1233,25 +1233,29 @@ vm_reserv_reclaim_inactive(int domain)
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/*
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* Determine whether this reservation has free pages that satisfy the given
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* request for contiguous physical memory. Start searching from the lower
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* bound, defined by low_index.
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* bound, defined by lo, and stop at the upper bound, hi. Return the index
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* of the first satisfactory free page, or -1 if none is found.
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*/
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static bool
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vm_reserv_test_contig(vm_reserv_t rv, u_long npages, vm_paddr_t low,
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vm_paddr_t high, u_long alignment, vm_paddr_t boundary)
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static int
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vm_reserv_find_contig(vm_reserv_t rv, int npages, int lo,
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int hi, int ppn_align, int ppn_bound)
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{
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vm_paddr_t pa, size;
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u_long changes;
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int bitpos, bits_left, i, hi, lo, n;
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int bitpos, bits_left, i, n;
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vm_reserv_assert_locked(rv);
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size = npages << PAGE_SHIFT;
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pa = VM_PAGE_TO_PHYS(&rv->pages[0]);
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lo = (pa < low) ?
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((low + PAGE_MASK - pa) >> PAGE_SHIFT) : 0;
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KASSERT(npages <= VM_LEVEL_0_NPAGES - 1,
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("%s: Too many pages", __func__));
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KASSERT(ppn_bound <= VM_LEVEL_0_NPAGES,
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("%s: Too big a boundary for reservation size", __func__));
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KASSERT(npages <= ppn_bound,
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("%s: Too many pages for given boundary", __func__));
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KASSERT(ppn_align != 0 && powerof2(ppn_align),
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("ppn_align is not a positive power of 2"));
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KASSERT(ppn_bound != 0 && powerof2(ppn_bound),
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("ppn_bound is not a positive power of 2"));
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i = lo / NBPOPMAP;
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changes = rv->popmap[i] | ((1UL << (lo % NBPOPMAP)) - 1);
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hi = (pa + VM_LEVEL_0_SIZE > high) ?
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((high + PAGE_MASK - pa) >> PAGE_SHIFT) : VM_LEVEL_0_NPAGES;
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n = hi / NBPOPMAP;
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bits_left = hi % NBPOPMAP;
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hi = lo = -1;
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@ -1276,25 +1280,20 @@ vm_reserv_test_contig(vm_reserv_t rv, u_long npages, vm_paddr_t low,
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continue;
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}
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hi = NBPOPMAP * i + bitpos;
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pa = VM_PAGE_TO_PHYS(&rv->pages[lo]);
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if ((pa & (alignment - 1)) != 0) {
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if (lo < roundup2(lo, ppn_align)) {
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/* Skip to next aligned page. */
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lo += (((pa - 1) | (alignment - 1)) + 1) >>
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PAGE_SHIFT;
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lo = roundup2(lo, ppn_align);
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if (lo >= VM_LEVEL_0_NPAGES)
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return (false);
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pa = VM_PAGE_TO_PHYS(&rv->pages[lo]);
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return (-1);
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}
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if (((pa ^ (pa + size - 1)) & ~(boundary - 1)) != 0) {
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if (lo + npages > roundup2(lo, ppn_bound)) {
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/* Skip to next boundary-matching page. */
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lo += (((pa - 1) | (boundary - 1)) + 1) >>
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PAGE_SHIFT;
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lo = roundup2(lo, ppn_bound);
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if (lo >= VM_LEVEL_0_NPAGES)
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return (false);
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pa = VM_PAGE_TO_PHYS(&rv->pages[lo]);
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return (-1);
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}
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if (lo * PAGE_SIZE + size <= hi * PAGE_SIZE)
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return (true);
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if (lo + npages <= hi)
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return (lo);
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lo = hi;
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}
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if (++i < n)
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@ -1303,7 +1302,7 @@ vm_reserv_test_contig(vm_reserv_t rv, u_long npages, vm_paddr_t low,
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changes = bits_left == 0 ? -1UL :
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(rv->popmap[n] | (-1UL << bits_left));
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else
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return (false);
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return (-1);
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}
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}
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@ -1320,12 +1319,32 @@ vm_reserv_reclaim_contig(int domain, u_long npages, vm_paddr_t low,
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struct vm_reserv_queue *queue;
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vm_paddr_t pa, size;
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vm_reserv_t marker, rv, rvn;
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int hi, lo, posn, ppn_align, ppn_bound;
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KASSERT(npages > 0, ("npages is 0"));
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KASSERT(powerof2(alignment), ("alignment is not a power of 2"));
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KASSERT(powerof2(boundary), ("boundary is not a power of 2"));
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if (npages > VM_LEVEL_0_NPAGES - 1)
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return (false);
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size = npages << PAGE_SHIFT;
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/*
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* Ensure that a free range starting at a boundary-multiple
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* doesn't include a boundary-multiple within it. Otherwise,
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* no boundary-constrained allocation is possible.
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*/
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if (size > boundary)
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return (false);
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marker = &vm_rvd[domain].marker;
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queue = &vm_rvd[domain].partpop;
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size = npages << PAGE_SHIFT;
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/*
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* Compute shifted alignment, boundary values for page-based
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* calculations. Constrain to range [1, VM_LEVEL_0_NPAGES] to
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* avoid overflow.
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*/
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ppn_align = (int)(ulmin(ulmax(PAGE_SIZE, alignment),
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VM_LEVEL_0_SIZE) >> PAGE_SHIFT);
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ppn_bound = (int)(MIN(MAX(PAGE_SIZE, boundary),
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VM_LEVEL_0_SIZE) >> PAGE_SHIFT);
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vm_reserv_domain_scan_lock(domain);
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vm_reserv_domain_lock(domain);
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@ -1339,6 +1358,10 @@ vm_reserv_reclaim_contig(int domain, u_long npages, vm_paddr_t low,
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/* This entire reservation is too high; go to next. */
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continue;
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}
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if ((pa & (alignment - 1)) != 0) {
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/* This entire reservation is unaligned; go to next. */
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continue;
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}
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if (vm_reserv_trylock(rv) == 0) {
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TAILQ_INSERT_AFTER(queue, rv, marker, partpopq);
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@ -1356,8 +1379,21 @@ vm_reserv_reclaim_contig(int domain, u_long npages, vm_paddr_t low,
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TAILQ_REMOVE(queue, marker, partpopq);
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}
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vm_reserv_domain_unlock(domain);
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if (vm_reserv_test_contig(rv, npages, low, high,
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alignment, boundary)) {
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lo = (pa >= low) ? 0 :
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(int)((low + PAGE_MASK - pa) >> PAGE_SHIFT);
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hi = (pa + VM_LEVEL_0_SIZE <= high) ? VM_LEVEL_0_NPAGES :
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(int)((high - pa) >> PAGE_SHIFT);
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posn = vm_reserv_find_contig(rv, (int)npages, lo, hi,
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ppn_align, ppn_bound);
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if (posn >= 0) {
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pa = VM_PAGE_TO_PHYS(&rv->pages[posn]);
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KASSERT((pa & (alignment - 1)) == 0,
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("%s: adjusted address does not align to %lx",
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__func__, alignment));
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KASSERT(((pa ^ (pa + size - 1)) & -boundary) == 0,
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("%s: adjusted address spans boundary to %lx",
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__func__, boundary));
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vm_reserv_domain_scan_unlock(domain);
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vm_reserv_reclaim(rv);
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vm_reserv_unlock(rv);
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