Re: [PATCH v4 10/38] infiniband: update hfi1 to use remap_vmalloc_range()

In cases which map chip memory from vmalloc()'d ranges, the hfi1 infiniband
drivers currently installs a fault handler, and then smuggles the kernel
virtual address of this range in vma->vm_pgoff.

This is exposing KASLR-sensitive internal kernel state in the VMA, and is
entirely unnecessary.

Instead, use remap_vmalloc_range() to remap the VMA to the span, and
eliminate the fault handler altogether.

remap_vmalloc_range() checks that the VMA does not extend beyond the
vmalloc area, and the driver already requires the VMA to exactly match the
span of the memory being mapped, so this has no impact.

The memory is all preallocated so not having a fault handler has no impact
[ ... ]
There is a change in behaviour in that pages mapped using
remap_vmalloc_range() will now have normal GUP-able pages, however this
should have no impact as there is no reason not to allow this.

Signed-off-by: Lorenzo Stoakes (ARM) <ljs@kernel.org>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261003-b4-mmap-prepare-vma-flag-sanify-v4-0-a1f052500fd7@kernel.org?part=10