* [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page
@ 2010-04-27 7:04 Huang Ying
2010-04-27 21:47 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: Huang Ying @ 2010-04-27 7:04 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, Andi Kleen, Avi Kivity
With this patch, the caller of __get_user_pages can distinguish
HWPOISON page from general FAULT page. This is needed by KVM, where
UCR MCE should be relayed to guest for HWPOISON page, while
instruction emulation and MMIO will be tried for general FAULT page.
Signed-off-by: Huang Ying <ying.huang@intel.com>
---
include/asm-generic/errno.h | 2 ++
mm/memory.c | 5 +++--
2 files changed, 5 insertions(+), 2 deletions(-)
--- a/include/asm-generic/errno.h
+++ b/include/asm-generic/errno.h
@@ -108,4 +108,6 @@
#define ERFKILL 132 /* Operation not possible due to RF-kill */
+#define EHWPOISON 133 /* Memory page has hardware error */
+
#endif
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1432,9 +1432,10 @@ int __get_user_pages(struct task_struct
if (ret & VM_FAULT_ERROR) {
if (ret & VM_FAULT_OOM)
return i ? i : -ENOMEM;
- if (ret &
- (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
+ if (ret & VM_FAULT_SIGBUS)
return i ? i : -EFAULT;
+ if (ret & VM_FAULT_HWPOISON)
+ return i ? i : -EHWPOISON;
BUG();
}
if (ret & VM_FAULT_MAJOR)
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page
2010-04-27 7:04 [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page Huang Ying
@ 2010-04-27 21:47 ` Andrew Morton
2010-04-28 1:50 ` Huang Ying
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Morton @ 2010-04-27 21:47 UTC (permalink / raw)
To: Huang Ying; +Cc: linux-kernel, Andi Kleen, Avi Kivity
On Tue, 27 Apr 2010 15:04:18 +0800
Huang Ying <ying.huang@intel.com> wrote:
> With this patch, the caller of __get_user_pages can distinguish
> HWPOISON page from general FAULT page. This is needed by KVM, where
> UCR MCE should be relayed to guest for HWPOISON page, while
> instruction emulation and MMIO will be tried for general FAULT page.
>
> Signed-off-by: Huang Ying <ying.huang@intel.com>
> ---
> include/asm-generic/errno.h | 2 ++
> mm/memory.c | 5 +++--
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> --- a/include/asm-generic/errno.h
> +++ b/include/asm-generic/errno.h
> @@ -108,4 +108,6 @@
>
> #define ERFKILL 132 /* Operation not possible due to RF-kill */
>
> +#define EHWPOISON 133 /* Memory page has hardware error */
> +
> #endif
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1432,9 +1432,10 @@ int __get_user_pages(struct task_struct
> if (ret & VM_FAULT_ERROR) {
> if (ret & VM_FAULT_OOM)
> return i ? i : -ENOMEM;
> - if (ret &
> - (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
> + if (ret & VM_FAULT_SIGBUS)
> return i ? i : -EFAULT;
> + if (ret & VM_FAULT_HWPOISON)
> + return i ? i : -EHWPOISON;
> BUG();
> }
> if (ret & VM_FAULT_MAJOR)
>
This will cause various code paths (eg: fs/direct-io.c) to return
-EHWPOISON to userspace, will it not?
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page
2010-04-27 21:47 ` Andrew Morton
@ 2010-04-28 1:50 ` Huang Ying
2010-04-27 22:56 ` Andrew Morton
0 siblings, 1 reply; 4+ messages in thread
From: Huang Ying @ 2010-04-28 1:50 UTC (permalink / raw)
To: Andrew Morton; +Cc: linux-kernel, Andi Kleen, Avi Kivity
On Wed, 2010-04-28 at 05:47 +0800, Andrew Morton wrote:
> On Tue, 27 Apr 2010 15:04:18 +0800
> Huang Ying <ying.huang@intel.com> wrote:
>
> > With this patch, the caller of __get_user_pages can distinguish
> > HWPOISON page from general FAULT page. This is needed by KVM, where
> > UCR MCE should be relayed to guest for HWPOISON page, while
> > instruction emulation and MMIO will be tried for general FAULT page.
> >
> > Signed-off-by: Huang Ying <ying.huang@intel.com>
> > ---
> > include/asm-generic/errno.h | 2 ++
> > mm/memory.c | 5 +++--
> > 2 files changed, 5 insertions(+), 2 deletions(-)
> >
> > --- a/include/asm-generic/errno.h
> > +++ b/include/asm-generic/errno.h
> > @@ -108,4 +108,6 @@
> >
> > #define ERFKILL 132 /* Operation not possible due to RF-kill */
> >
> > +#define EHWPOISON 133 /* Memory page has hardware error */
> > +
> > #endif
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -1432,9 +1432,10 @@ int __get_user_pages(struct task_struct
> > if (ret & VM_FAULT_ERROR) {
> > if (ret & VM_FAULT_OOM)
> > return i ? i : -ENOMEM;
> > - if (ret &
> > - (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
> > + if (ret & VM_FAULT_SIGBUS)
> > return i ? i : -EFAULT;
> > + if (ret & VM_FAULT_HWPOISON)
> > + return i ? i : -EHWPOISON;
> > BUG();
> > }
> > if (ret & VM_FAULT_MAJOR)
> >
>
> This will cause various code paths (eg: fs/direct-io.c) to return
> -EHWPOISON to userspace, will it not?
Yes. I think it may be returned to userspace. Do we need to keep the
userspace errno interface like this?
If it is, we can check whether the virtual page is hwpoisoned via going
through the page table because the hwpoisoned virtual page has a special
swap entry in page table.
Best Regards,
Huang Ying
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page
2010-04-28 1:50 ` Huang Ying
@ 2010-04-27 22:56 ` Andrew Morton
0 siblings, 0 replies; 4+ messages in thread
From: Andrew Morton @ 2010-04-27 22:56 UTC (permalink / raw)
To: Huang Ying; +Cc: linux-kernel, Andi Kleen, Avi Kivity
On Wed, 28 Apr 2010 09:50:12 +0800 Huang Ying <ying.huang@intel.com> wrote:
> On Wed, 2010-04-28 at 05:47 +0800, Andrew Morton wrote:
> > On Tue, 27 Apr 2010 15:04:18 +0800
> > Huang Ying <ying.huang@intel.com> wrote:
> >
>
> ...
>
> > > if (ret & VM_FAULT_ERROR) {
> > > if (ret & VM_FAULT_OOM)
> > > return i ? i : -ENOMEM;
> > > - if (ret &
> > > - (VM_FAULT_HWPOISON|VM_FAULT_SIGBUS))
> > > + if (ret & VM_FAULT_SIGBUS)
> > > return i ? i : -EFAULT;
> > > + if (ret & VM_FAULT_HWPOISON)
> > > + return i ? i : -EHWPOISON;
> > > BUG();
> > > }
> > > if (ret & VM_FAULT_MAJOR)
> > >
> >
> > This will cause various code paths (eg: fs/direct-io.c) to return
> > -EHWPOISON to userspace, will it not?
>
> Yes. I think it may be returned to userspace. Do we need to keep the
> userspace errno interface like this?
I don't think we should extend the kernel interface in a non-posix
fashion without good reason and some thought. manpages and glibc will
need to be updated, etc..
> If it is, we can check whether the virtual page is hwpoisoned via going
> through the page table because the hwpoisoned virtual page has a special
> swap entry in page table.
Spose so. Or you could perhaps extend __get_user_pages() by adding a
new FOLL_HWPOISON and make it return -EHWPOISON only if FOLL_HWPOISON
was set, and require that the __get_user_pages(FOLL_HWPOISON) caller
rewrite -EHWPOISON to something else. But I didn't think about that
very hard.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2010-04-28 1:58 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2010-04-27 7:04 [PATCH 1/2] mm, Make __get_user_pages return -EHWPOISON for HWPOISON page Huang Ying
2010-04-27 21:47 ` Andrew Morton
2010-04-28 1:50 ` Huang Ying
2010-04-27 22:56 ` Andrew Morton
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