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> > > } > > > +#define MAX_UMAP_ENTRIES 1024 > > > > Only 170 of these fit in a 4k page :\ > > > > Are you worried about the high order allocation this could trigger? > > Should I worry? Probably? Experiance shows busy servers cannot do a high order allocation, even order 4 is likely to fail due to fragmentation. If you imagine you will need more than 1-4 pages of this then it would probably be a good idea to avoid the higher order allocation., > I define a max to guard against a DOS from userland requesting a huge number > of entries and causing the driver to allocate a huge amount of memory. > > The use cases I have seen only have dozens of entries. Do you have a figure > in mind for the upper bound? Then it is probably fine as is Jason