On Fri 29-06-18 07:02:24, Shakeel Butt wrote:
The size of kvm's shadow page tables corresponds to the size of the guest virtual machines on the system. Large VMs can spend a significant amount of memory as shadow page tables which can not be left as system memory overhead. So, account shadow page tables to the kmemcg.
Signed-off-by: Shakeel Butt shakeelb@google.com Cc: Michal Hocko mhocko@kernel.org Cc: Johannes Weiner hannes@cmpxchg.org Cc: Vladimir Davydov vdavydov.dev@gmail.com Cc: Paolo Bonzini pbonzini@redhat.com Cc: Greg Thelen gthelen@google.com Cc: Radim Krčmář rkrcmar@redhat.com Cc: Peter Feiner pfeiner@google.com Cc: Andrew Morton akpm@linux-foundation.org Cc: stable@vger.kernel.org
I am not familiar wtih kvm to judge but if we are going to account this memory we will probably want to let oom_badness know how much memory to account to a specific process. Is this something that we can do? We will probably need a new MM_KERNEL rss_stat stat for that purpose.
Just to make it clear. I am not opposing to this patch but considering that shadow page tables might consume a lot of memory it would be good to know who is responsible for it from the OOM perspective. Something to solve on top of this.
I would also love to see a note how this memory is bound to the owner life time in the changelog. That would make the review much more easier.
Changelog since v1:
- replaced (GFP_KERNEL|__GFP_ACCOUNT) with GFP_KERNEL_ACCOUNT
arch/x86/kvm/mmu.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c index d594690d8b95..6b8f11521c41 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -890,7 +890,7 @@ static int mmu_topup_memory_cache_page(struct kvm_mmu_memory_cache *cache, if (cache->nobjs >= min) return 0; while (cache->nobjs < ARRAY_SIZE(cache->objects)) {
page = (void *)__get_free_page(GFP_KERNEL);
page = (void *)__get_free_page(GFP_KERNEL_ACCOUNT);-- 2.18.0.rc2.346.g013aa6912e-goog