Re-enable NUMA memory binding on newer kernels

lib/ljsyscall/syscall/linux/syscalls.lua

@@ -483,33 +483,30 @@ local function get_maxnumnodes()
        return math.floor(((#line+1)/9)*32)
      end
    end
+   -- If we don't know, guess that the system has a max of 1024 nodes.
+   return 1024
+end
+
+local function ensure_bitmask(mask, size)
+  if ffi.istype(t.bitmask, mask) then return mask end
+  return t.bitmask(mask, size or get_maxnumnodes())
 end
 
 function S.get_mempolicy(mode, mask, addr, flags)
   mode = mode or t.int1()
-  local size
-  if ffi.istype(t.bitmask, mask) then
-    -- if mask was provided by the caller, then use its size
-    -- and let the syscall error if it's too small
-    size = ffi.cast("uint64_t", tonumber(mask.size))
-  else
-    local mask_for_size = t.bitmask(mask)
-    -- Size should be at least equals to maxnumnodes.
-    size = ffi.cast("uint64_t", math.max(tonumber(mask_for_size.size), get_maxnumnodes()))
-    mask = t.bitmask(mask, tonumber(size))
-  end
-  local ret, err = C.get_mempolicy(mode, mask.mask, size, addr or 0, c.MPOL_FLAG[flags])
+  mask = ensure_bitmask(mask);
+  local ret, err = C.get_mempolicy(mode, mask.mask, mask.size, addr or 0, c.MPOL_FLAG[flags])
   if ret == -1 then return nil, t.error(err or errno()) end
   return { mode=mode[0], mask=mask }
 end
 function S.set_mempolicy(mode, mask)
-  mask = mktype(t.bitmask, mask)
+  mask = ensure_bitmask(mask);
   return retbool(C.set_mempolicy(c.MPOL_MODE[mode], mask.mask, mask.size))
 end
 
 function S.migrate_pages(pid, from, to)
-  from = mktype(t.bitmask, from)
-  to = mktype(t.bitmask, to)
+  from = ensure_bitmask(from);
+  to = ensure_bitmask(to, from.size)
   assert(from.size == to.size, "incompatible nodemask sizes")
   return retbool(C.migrate_pages(pid or 0, from.size, from.mask, to.mask))
 end

src/lib/numa.lua

@@ -97,57 +97,6 @@ function unbind_cpu ()
    bound_cpu = nil
 end
 
-local blacklisted_kernels = {
-   '>=4.15',
-}
-local function sys_kernel ()
-   return lib.readfile('/proc/sys/kernel/osrelease', '*all'):gsub('%s$', '')
-end
-local function parse_version_number (str)
-   local t = {}
-   for each in str:gmatch("([^.]+)") do
-      table.insert(t, tonumber(each) or 0)
-   end
-   return t
-end
-local function equals (v1, v2)
-   for i, p1 in ipairs(v1) do
-      local p2 = v2[i] or 0
-      if p1 ~= p2 then return false end
-   end
-   return true
-end
-local function greater_or_equals (v1, v2)
-   for i, p1 in ipairs(v1) do
-      local p2 = v2[i] or 0
-      if p2 > p1 then return false end
-   end
-   return true
-end
-local function greater (v1, v2)
-   return greater_or_equals(v1, v2) and not equals(v1, v2)
-end
-function is_blacklisted_kernel (v)
-   for _, each in ipairs(blacklisted_kernels) do
-      -- Greater or equal.
-      if each:sub(1, 2) == '>=' then
-         each = each:sub(3, #each)
-         local v1, v2 = parse_version_number(v), parse_version_number(each)
-         if greater_or_equals(v1, v2) then return true end
-      -- Greater than.
-      elseif each:sub(1, 1) == '>' then
-         each = each:sub(2, #each)
-         local v1, v2 = parse_version_number(v), parse_version_number(each)
-         if greater(v1, v2) then return true end
-      -- Equals.
-      else
-         local v1, v2 = parse_version_number(v), parse_version_number(each)
-         if equals(v1, v2) then return true end
-      end
-   end
-   return false
-end
-
 function bind_to_cpu (cpu)
    local function contains (t, e)
       for k,v in ipairs(t) do
@@ -177,11 +126,6 @@ function unbind_numa_node ()
 end
 
 function bind_to_numa_node (node, policy)
-   local kernel = sys_kernel()
-   if is_blacklisted_kernel(kernel) then
-      print(("WARNING: Buggy kernel '%s'. Not binding CPU to NUMA node."):format(kernel))
-      return
-   end
    if node == bound_numa_node then return end
    if not node then return unbind_numa_node() end
    assert(not bound_numa_node, "already bound")
@@ -247,9 +191,5 @@ function selftest ()
       test_pci_affinity(pciaddr)
    end
 
-   assert(greater(parse_version_number('4.15'), parse_version_number('4.4.80')))
-   assert(greater_or_equals(parse_version_number('4.15'), parse_version_number('4.15')))
-   assert(not greater(parse_version_number('4.14'), parse_version_number('4.15')))
-
    print('selftest: numa: ok')
 end