[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH v2] x86/mem_sharing: Resolve mm-lock order violations when forking VMs with nested p2m
On Thu, Jan 7, 2021 at 8:55 AM Jan Beulich <jbeulich@xxxxxxxx> wrote: > > On 07.01.2021 14:23, Tamas K Lengyel wrote: > > Several lock-order violations have been encountered while attempting to fork > > VMs with nestedhvm=1 set. This patch resolves the issues. > > > > The order violations stems from a call to p2m_flush_nestedp2m being > > performed > > whenever the hostp2m changes. This functions always takes the p2m lock for > > the > > nested_p2m. However, with sharing the p2m locks always have to be taken > > before > > the sharing lock. To resolve this issue we avoid taking the sharing lock > > where > > possible (and was actually unecessary to begin with). But we also make > > p2m_flush_nestedp2m aware that the p2m lock may have already been taken and > > preemptively take all nested_p2m locks before unsharing a page where taking > > the > > sharing lock is necessary. > > > > Signed-off-by: Tamas K Lengyel <tamas.lengyel@xxxxxxxxx> > > Acked-by: Jan Beulich <jbeulich@xxxxxxxx> Thanks, Tamas
|
Lists.xenproject.org is hosted with RackSpace, monitoring our |