[PATCH v2] s390/gmap: return proper error code on ksm unsharing

[PATCH v2] s390/gmap: return proper error code on ksm unsharing

[Christian Borntraeger]

If a signal is pending we might return -ENOMEM instead of -EINTR.
We should propagate the proper error during KSM unsharing.

Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
---
 arch/s390/mm/gmap.c | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 27926a06df32..1ef864c252e6 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2552,12 +2552,13 @@ int gmap_mark_unmergeable(void)
 {
 	struct mm_struct *mm = current->mm;
 	struct vm_area_struct *vma;
+	int ret;
 
 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
-		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
-				MADV_UNMERGEABLE, &vma->vm_flags)) {
-			return -ENOMEM;
-		}
+		ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,
+				  MADV_UNMERGEABLE, &vma->vm_flags);
+		if (ret)
+			return ret;
 	}
 	mm->def_flags &= ~VM_MERGEABLE;
 	return 0;
-- 
2.25.1

Re: [PATCH v2] s390/gmap: return proper error code on ksm unsharing

[David Hildenbrand]

On 27.03.20 10:23, Christian Borntraeger wrote:
> If a signal is pending we might return -ENOMEM instead of -EINTR.
> We should propagate the proper error during KSM unsharing.
> 
> Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
> Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/mm/gmap.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index 27926a06df32..1ef864c252e6 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -2552,12 +2552,13 @@ int gmap_mark_unmergeable(void)
>  {
>  	struct mm_struct *mm = current->mm;
>  	struct vm_area_struct *vma;
> +	int ret;
>  
>  	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> -		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
> -				MADV_UNMERGEABLE, &vma->vm_flags)) {
> -			return -ENOMEM;
> -		}
> +		ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,
> +				  MADV_UNMERGEABLE, &vma->vm_flags);
> +		if (ret)
> +			return ret;
>  	}
>  	mm->def_flags &= ~VM_MERGEABLE;
>  	return 0;
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb

Re: [PATCH v2] s390/gmap: return proper error code on ksm unsharing

[Cornelia Huck]

On Fri, 27 Mar 2020 05:23:56 -0400
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> If a signal is pending we might return -ENOMEM instead of -EINTR.
> We should propagate the proper error during KSM unsharing.
> 
> Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
> Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/mm/gmap.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 

Reviewed-by: Cornelia Huck <cohuck@redhat.com>

Re: [PATCH v2] s390/gmap: return proper error code on ksm unsharing

[Christian Borntraeger]

On 27.03.20 10:23, Christian Borntraeger wrote:
> If a signal is pending we might return -ENOMEM instead of -EINTR.
> We should propagate the proper error during KSM unsharing.
> 
> Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
> Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> ---
>  arch/s390/mm/gmap.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
> index 27926a06df32..1ef864c252e6 100644
> --- a/arch/s390/mm/gmap.c
> +++ b/arch/s390/mm/gmap.c
> @@ -2552,12 +2552,13 @@ int gmap_mark_unmergeable(void)
>  {
>  	struct mm_struct *mm = current->mm;
>  	struct vm_area_struct *vma;
> +	int ret;
>  
>  	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> -		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
> -				MADV_UNMERGEABLE, &vma->vm_flags)) {
> -			return -ENOMEM;
> -		}
> +		ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,
> +				  MADV_UNMERGEABLE, &vma->vm_flags);
> +		if (ret)
> +			return ret;
>  	}
>  	mm->def_flags &= ~VM_MERGEABLE;
>  	return 0;


After the qemu patch discussion I would add


diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
index 0e268b3d1591..ba8f9cbe4376 100644
--- a/Documentation/virt/kvm/api.rst
+++ b/Documentation/virt/kvm/api.rst
@@ -4680,6 +4680,12 @@ KVM_PV_ENABLE
   command has succeeded, any CPU added via hotplug will become
   protected during its creation as well.
 
+  Errors:
+
+  =====      =============================
+  EINTR      an unmasked signal is pending
+  =====      =============================
+
 KVM_PV_DISABLE
 
   Deregister the VM from the Ultravisor and reclaim the memory that


and change the patch description to something like


    s390/gmap: return proper error code on ksm unsharing
    
    If a signal is pending we might return -ENOMEM instead of -EINTR.
    We should propagate the proper error during KSM unsharing.
    unmerge_ksm_pages returns -ERESTARTSYS on signal_pending. This gets
    translated by entry.S to -EINTR. It is important to get this error
    code so that userspace can retry.
    
    Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
    Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
    Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
    Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
    Reviewed-by: David Hildenbrand <david@redhat.com>
    Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>

Re: [PATCH v2] s390/gmap: return proper error code on ksm unsharing

[David Hildenbrand]

On 27.03.20 11:23, Christian Borntraeger wrote:
> On 27.03.20 10:23, Christian Borntraeger wrote:
>> If a signal is pending we might return -ENOMEM instead of -EINTR.
>> We should propagate the proper error during KSM unsharing.
>>
>> Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
>> Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
>> Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
>> ---
>>  arch/s390/mm/gmap.c | 9 +++++----
>>  1 file changed, 5 insertions(+), 4 deletions(-)
>>
>> diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
>> index 27926a06df32..1ef864c252e6 100644
>> --- a/arch/s390/mm/gmap.c
>> +++ b/arch/s390/mm/gmap.c
>> @@ -2552,12 +2552,13 @@ int gmap_mark_unmergeable(void)
>>  {
>>  	struct mm_struct *mm = current->mm;
>>  	struct vm_area_struct *vma;
>> +	int ret;
>>  
>>  	for (vma = mm->mmap; vma; vma = vma->vm_next) {
>> -		if (ksm_madvise(vma, vma->vm_start, vma->vm_end,
>> -				MADV_UNMERGEABLE, &vma->vm_flags)) {
>> -			return -ENOMEM;
>> -		}
>> +		ret = ksm_madvise(vma, vma->vm_start, vma->vm_end,
>> +				  MADV_UNMERGEABLE, &vma->vm_flags);
>> +		if (ret)
>> +			return ret;
>>  	}
>>  	mm->def_flags &= ~VM_MERGEABLE;
>>  	return 0;
> 
> 
> After the qemu patch discussion I would add
> 
> 
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 0e268b3d1591..ba8f9cbe4376 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -4680,6 +4680,12 @@ KVM_PV_ENABLE
>    command has succeeded, any CPU added via hotplug will become
>    protected during its creation as well.
>  
> +  Errors:
> +
> +  =====      =============================
> +  EINTR      an unmasked signal is pending
> +  =====      =============================
> +
>  KVM_PV_DISABLE
>  
>    Deregister the VM from the Ultravisor and reclaim the memory that
> 
> 
> and change the patch description to something like
> 
> 
>     s390/gmap: return proper error code on ksm unsharing
>     
>     If a signal is pending we might return -ENOMEM instead of -EINTR.
>     We should propagate the proper error during KSM unsharing.
>     unmerge_ksm_pages returns -ERESTARTSYS on signal_pending. This gets
>     translated by entry.S to -EINTR. It is important to get this error
>     code so that userspace can retry.
>     
>     Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
>     Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
>     Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>     Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>     Reviewed-by: David Hildenbrand <david@redhat.com>
>     Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> 

Looks good.

-- 
Thanks,

David / dhildenb

Re: [PATCH v2] s390/gmap: return proper error code on ksm unsharing

[Cornelia Huck]

On Fri, 27 Mar 2020 11:23:33 +0100
Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> On 27.03.20 10:23, Christian Borntraeger wrote:

> After the qemu patch discussion I would add
> 
> 
> diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> index 0e268b3d1591..ba8f9cbe4376 100644
> --- a/Documentation/virt/kvm/api.rst
> +++ b/Documentation/virt/kvm/api.rst
> @@ -4680,6 +4680,12 @@ KVM_PV_ENABLE
>    command has succeeded, any CPU added via hotplug will become
>    protected during its creation as well.
>  
> +  Errors:
> +
> +  =====      =============================
> +  EINTR      an unmasked signal is pending
> +  =====      =============================
> +
>  KVM_PV_DISABLE
>  
>    Deregister the VM from the Ultravisor and reclaim the memory that
> 
> 
> and change the patch description to something like
> 
> 
>     s390/gmap: return proper error code on ksm unsharing
>     
>     If a signal is pending we might return -ENOMEM instead of -EINTR.
>     We should propagate the proper error during KSM unsharing.
>     unmerge_ksm_pages returns -ERESTARTSYS on signal_pending. This gets
>     translated by entry.S to -EINTR. It is important to get this error
>     code so that userspace can retry.
>     
>     Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
>     Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
>     Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>     Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
>     Reviewed-by: David Hildenbrand <david@redhat.com>
>     Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> 

LGTM

Re: [PATCH v2] s390/gmap: return proper error code on ksm unsharing

[Cornelia Huck]

On Fri, 27 Mar 2020 11:39:54 +0100
Cornelia Huck <cohuck@redhat.com> wrote:

> On Fri, 27 Mar 2020 11:23:33 +0100
> Christian Borntraeger <borntraeger@de.ibm.com> wrote:
> 
> > On 27.03.20 10:23, Christian Borntraeger wrote:
> 
> > After the qemu patch discussion I would add
> > 
> > 
> > diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst
> > index 0e268b3d1591..ba8f9cbe4376 100644
> > --- a/Documentation/virt/kvm/api.rst
> > +++ b/Documentation/virt/kvm/api.rst
> > @@ -4680,6 +4680,12 @@ KVM_PV_ENABLE
> >    command has succeeded, any CPU added via hotplug will become
> >    protected during its creation as well.
> >  
> > +  Errors:
> > +
> > +  =====      =============================
> > +  EINTR      an unmasked signal is pending
> > +  =====      =============================
> > +
> >  KVM_PV_DISABLE
> >  
> >    Deregister the VM from the Ultravisor and reclaim the memory that
> > 
> > 
> > and change the patch description to something like
> > 
> > 
> >     s390/gmap: return proper error code on ksm unsharing
> >     
> >     If a signal is pending we might return -ENOMEM instead of -EINTR.
> >     We should propagate the proper error during KSM unsharing.
> >     unmerge_ksm_pages returns -ERESTARTSYS on signal_pending. This gets
> >     translated by entry.S to -EINTR. It is important to get this error
> >     code so that userspace can retry.
> >     
> >     Fixes: 3ac8e38015d4 ("s390/mm: disable KSM for storage key enabled pages")
> >     Reviewed-by: Janosch Frank <frankja@linux.vnet.ibm.com>
> >     Reported-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> >     Tested-by: Marc Hartmayer <mhartmay@linux.ibm.com>
> >     Reviewed-by: David Hildenbrand <david@redhat.com>
> >     Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
> > 
> 
> LGTM

...well, if you add my

Reviewed-by: Cornelia Huck <cohuck@redhat.com>