From: David Hildenbrand Sent: November 14, 2018 at 11:05:38 PM GMT > Subject: Re: [PATCH RFC 0/6] mm/kdump: allow to exclude pages that are logically offline > > > On 14.11.18 23:57, Nadav Amit wrote: >> From: David Hildenbrand >> Sent: November 14, 2018 at 9:16:58 PM GMT >>> Subject: [PATCH RFC 0/6] mm/kdump: allow to exclude pages that are logically offline >>> >>> >>> Right now, pages inflated as part of a balloon driver will be dumped >>> by dump tools like makedumpfile. While XEN is able to check in the >>> crash kernel whether a certain pfn is actuall backed by memory in the >>> hypervisor (see xen_oldmem_pfn_is_ram) and optimize this case, dumps of >>> virtio-balloon and hv-balloon inflated memory will essentially result in >>> zero pages getting allocated by the hypervisor and the dump getting >>> filled with this data. >> >> Is there any reason that VMware balloon driver is not mentioned? > > Definitely ... > > ... not ;) . I haven't looked at vmware's balloon driver yet (I only saw > that there was quite some activity recently). I guess it should have > similar problems. (I mean reading and dumping data nobody cares about is > certainly not desired) > > Can you share if something like this is also desired for vmware's > implementation? (I tagged this as RFC to get some more feedback) > > It should in theory be as simple as adding a handful of > _SetPageOffline()/_ClearPageOffline() at the right spots. Thanks, I was just suspecting it is personal ;-) Actually, some patches that I sent for 4.20 to use the balloon-compaction infrastructure by the VMware balloon fell between the cracks, and I need to resend them. I would obviously prefer that your changes would be done on top of those that were skipped. This patch-set sounds very reasonable to me, but I prefer that Julien (cc’d) would also give his opinion. Regards, Nadav
