Re: [PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-24 Thread David Hildenbrand
On 23.10.19 09:26, David Hildenbrand wrote: On 22.10.19 23:54, Dan Williams wrote: Hi David, Thanks for tackling this! Thanks for having a look :) [...] I am probably a little bit too careful (but I don't want to break things). In most places (besides KVM and vfio that are nuts), the pfn_

Re: [PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-23 Thread David Hildenbrand
On 23.10.19 21:39, Dan Williams wrote: > On Wed, Oct 23, 2019 at 10:28 AM David Hildenbrand wrote: >> I dislike this for three reasons a) It does not protect against any races, really, it does not improve things. b) We do have the exact same problem with pfn_to_online_pag

Re: [PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-23 Thread Dan Williams
On Wed, Oct 23, 2019 at 10:28 AM David Hildenbrand wrote: > > >> I dislike this for three reasons > >> > >> a) It does not protect against any races, really, it does not improve > >> things. > >> b) We do have the exact same problem with pfn_to_online_page(). As long as > >> we > >>don't hol

Re: [PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-23 Thread David Hildenbrand
>> I dislike this for three reasons >> >> a) It does not protect against any races, really, it does not improve things. >> b) We do have the exact same problem with pfn_to_online_page(). As long as we >>don't hold the memory hotplug lock, memory can get offlined and remove >> any time. Racy. >

Re: [PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-23 Thread Dan Williams
On Wed, Oct 23, 2019 at 12:26 AM David Hildenbrand wrote: > > On 22.10.19 23:54, Dan Williams wrote: > > Hi David, > > > > Thanks for tackling this! > > Thanks for having a look :) > > [...] > > > >> I am probably a little bit too careful (but I don't want to break things). > >> In most places (be

Re: [PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-23 Thread David Hildenbrand
On 22.10.19 23:54, Dan Williams wrote: > Hi David, > > Thanks for tackling this! Thanks for having a look :) [...] >> I am probably a little bit too careful (but I don't want to break things). >> In most places (besides KVM and vfio that are nuts), the >> pfn_to_online_page() check could most

Re: [PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-22 Thread Dan Williams
Hi David, Thanks for tackling this! On Tue, Oct 22, 2019 at 10:13 AM David Hildenbrand wrote: > > This series is based on [2], which should pop up in linux/next soon: > https://lkml.org/lkml/2019/10/21/1034 > > This is the result of a recent discussion with Michal ([1], [2]). Right > now

[PATCH RFC v1 00/12] mm: Don't mark hotplugged pages PG_reserved (including ZONE_DEVICE)

2019-10-22 Thread David Hildenbrand
This series is based on [2], which should pop up in linux/next soon: https://lkml.org/lkml/2019/10/21/1034 This is the result of a recent discussion with Michal ([1], [2]). Right now we set all pages PG_reserved when initializing hotplugged memmaps. This includes ZONE_DEVICE memory. In cas