tree 0bf89d34e5290ae34773a390fea85b546772b625
parent b23e5844dfe78a80ba672793187d3f52e4b528d7
author Juergen Gross <jgross@suse.com> 1560934856 +0200
committer Juergen Gross <jgross@suse.com> 1563425064 +0200

xen: let alloc_xenballooned_pages() fail if not enough memory free

Instead of trying to allocate pages with GFP_USER in
add_ballooned_pages() check the available free memory via
si_mem_available(). GFP_USER is far less limiting memory exhaustion
than the test via si_mem_available().

This will avoid dom0 running out of memory due to excessive foreign
page mappings especially on ARM and on x86 in PVH mode, as those don't
have a pre-ballooned area which can be used for foreign mappings.

As the normal ballooning suffers from the same problem don't balloon
down more than si_mem_available() pages in one iteration. At the same
time limit the default maximum number of retries.

This is part of XSA-300.

Signed-off-by: Juergen Gross <jgross@suse.com>