Hi Wei, On Mon, Mar 10, 2025 at 07:56:27AM +0000, Wei Yang wrote: > On Wed, Feb 26, 2025 at 02:09:15AM +0000, Wei Yang wrote: > >>> > >>> From the above call flow and background, there are three cases when > >>> memblock_alloc_range_nid() would be called: > >>> > >>> * If it is called before (1), memblock.reserved's nid would be adjusted correctly. > >>> * If it is called after (2), we don't touch memblock.reserved. > >>> * If it happens between (1) and (2), it looks would break the consistency of > >>> nid information in memblock.reserved. Because when we use > >>> memblock_reserve_kern(), NUMA_NO_NODE would be stored in region. > >>> > >>> So my question is if the third case happens, would it introduce a bug? If it > >>> won't happen, seems we don't need to specify the nid here? > >> > >>We don't really care about proper assignment of nodes between (1) and (2) > >>from one side and the third case does not happen on the other side. Nothing > >>should call membloc_alloc() after memblock_free_all(). > >> > > > >My point is if no one would call memblock_alloc() after memblock_free_all(), > >which set nid in memblock.reserved properly, it seems not necessary to do > >__memblock_reserve() with exact nid during memblock_alloc()? > > > >As you did __memblock_reserve(found, size, nid, MEMBLOCK_RSRV_KERN) in this > >patch. > > > > Hi, Mike > > Do you think my understanding is reasonable? Without KHO it is indeed not strictly necessary to set nid during memblock_alloc(). But since we anyway have nid parameter in memblock_alloc_range_nid() and it anyway propagates to memblock_add_range(), I think it's easier and cleaner to pass nid to __memblock_reserve() there. And for KHO estimation of scratch size it is important to have nid assigned to the reserved areas before memblock_free_all(), at least for the allocations that request particular nid explicitly. > -- > Wei Yang > Help you, Help me -- Sincerely yours, Mike.
