VM_KMEM_SIZE_MAX allows to limit kmem arena size. In our case this was
necessary, as decreasing size of kmem_arena leaves more space for
kernel_arena.
kernel_arena is pool used for contigmalloc (in effect, DMA) allocations,
which failed on Armada38x. This resulted in 'no memory errors' (e.g.
USB_ERR_NOMEM errors) and failure of whole system. The need for greater
size of kernel_arena probably comes from more peripherals making use of busdma.
Value used as upper limit is half of the default value (0x1399a000).
Submitted by: Wojciech Macek <wma@semihalf.com>
Obtained from: Semihalf
Sponsored by: Stormshield
Reviewed by:
Differential revision: