Failure in update_l1e()

Failure in update_l1e()

[Jacob Gorm Hansen]

hi,

I am seeing occasional failures of cmpxchg_user() in update_l1e().
According to the the comments in the source, this is due to a page fault
caused by the update.

The error looks like this:

(XEN) DOM5: (file=memory.c, line=670) Failed to update 08fe6065 ->
08fe6465: saw 08fe6065
DOM5: Failed update VA mapping: 000bffff, 08fe6465, 00000002

The odd value is due to a special use of one of the AVL bits for my own
purposes.

This only happens when page_nr is 000bffff for some reason.

Any ideas what may be going wrong here?

thanks,
Jacob



-------------------------------------------------------
This SF.Net email is sponsored by: IBM Linux Tutorials
Free Linux tutorial presented by Daniel Robbins, President and CEO of
GenToo technologies. Learn everything from fundamentals to system
administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click

Re: Failure in update_l1e()

[Keir Fraser]

> hi,
> 
> I am seeing occasional failures of cmpxchg_user() in update_l1e().
> According to the the comments in the source, this is due to a page fault
> caused by the update.
> 
> The error looks like this:
> 
> (XEN) DOM5: (file=memory.c, line=670) Failed to update 08fe6065 ->
> 08fe6465: saw 08fe6065
> DOM5: Failed update VA mapping: 000bffff, 08fe6465, 00000002
> 
> The odd value is due to a special use of one of the AVL bits for my own
> purposes.
> 
> This only happens when page_nr is 000bffff for some reason.
> 
> Any ideas what may be going wrong here?

Most likely the page that you are trying to modify is mapped
read-only.

Any PTE linear address passed to update_va_mapping() /must/ be
writeable, or teh update will fail.

 -- Keir


-------------------------------------------------------
This SF.Net email is sponsored by: IBM Linux Tutorials
Free Linux tutorial presented by Daniel Robbins, President and CEO of
GenToo technologies. Learn everything from fundamentals to system
administration.http://ads.osdn.com/?ad_id=1470&alloc_id=3638&op=click