redonkable
/
alistair23-linux
1
0
Fork 0
Code Releases Activity

KVM: MMU: reclaim the zapped-obsolete page first 

As Marcelo pointed out that
| "(retention of large number of pages while zapping)
| can be fatal, it can lead to OOM and host crash"

We introduce a list, kvm->arch.zapped_obsolete_pages, to link all
the pages which are deleted from the mmu cache but not actually
freed. When page reclaiming is needed, we always zap this kind of
pages first.

Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Reviewed-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Gleb Natapov <gleb@redhat.com>
hifive-unleashed-5.1
Xiao Guangrong 2013-05-31 08:36:29 +08:00 committed by Gleb Natapov
parent f34d251d66
commit 365c886860
3 changed files with 20 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
arch/x86/include/asm/kvm_host.h
View File

@ -536,6 +536,8 @@ struct kvm_arch {
* Hash table of struct kvm_mmu_page.
*/
struct list_head active_mmu_pages;
struct list_head zapped_obsolete_pages;
struct list_head assigned_dev_head;
struct iommu_domain *iommu_domain;
int iommu_flags;

21
arch/x86/kvm/mmu.c
View File

@ -4211,7 +4211,6 @@ void kvm_mmu_slot_remove_write_access(struct kvm *kvm, int slot)
static void kvm_zap_obsolete_pages(struct kvm *kvm)
{
struct kvm_mmu_page *sp, *node;
LIST_HEAD(invalid_list);
int batch = 0;
restart:
@ -4244,7 +4243,8 @@ restart:
goto restart;
}
ret = kvm_mmu_prepare_zap_page(kvm, sp, &invalid_list);
ret = kvm_mmu_prepare_zap_page(kvm, sp,
&kvm->arch.zapped_obsolete_pages);
batch += ret;
if (ret)
@ -4255,7 +4255,7 @@ restart:
* Should flush tlb before free page tables since lockless-walking
* may use the pages.
*/
kvm_mmu_commit_zap_page(kvm, &invalid_list);
kvm_mmu_commit_zap_page(kvm, &kvm->arch.zapped_obsolete_pages);
}
/*
@ -4306,6 +4306,11 @@ restart:
spin_unlock(&kvm->mmu_lock);
}
static bool kvm_has_zapped_obsolete_pages(struct kvm *kvm)
{
return unlikely(!list_empty_careful(&kvm->arch.zapped_obsolete_pages));
}
static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)
{
struct kvm *kvm;
@ -4334,15 +4339,23 @@ static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)
* want to shrink a VM that only started to populate its MMU
* anyway.
*/
if (!kvm->arch.n_used_mmu_pages)
if (!kvm->arch.n_used_mmu_pages &&
!kvm_has_zapped_obsolete_pages(kvm))
continue;
idx = srcu_read_lock(&kvm->srcu);
spin_lock(&kvm->mmu_lock);
if (kvm_has_zapped_obsolete_pages(kvm)) {
kvm_mmu_commit_zap_page(kvm,
&kvm->arch.zapped_obsolete_pages);
goto unlock;
}
prepare_zap_oldest_mmu_page(kvm, &invalid_list);
kvm_mmu_commit_zap_page(kvm, &invalid_list);
unlock:
spin_unlock(&kvm->mmu_lock);
srcu_read_unlock(&kvm->srcu, idx);

1
arch/x86/kvm/x86.c
View File

@ -6832,6 +6832,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
return -EINVAL;
INIT_LIST_HEAD(&kvm->arch.active_mmu_pages);
INIT_LIST_HEAD(&kvm->arch.zapped_obsolete_pages);
INIT_LIST_HEAD(&kvm->arch.assigned_dev_head);
/* Reserve bit 0 of irq_sources_bitmap for userspace irq source */