[Xen-devel] RE: [PATCH] mem_sharing: fix race condition of nominate and unshare

[MaoXiaoyun <tinnycloud@xxxxxxxxxxx>]

Hi Juihao:
 
     I have no xenpaging run.
     Is it only necessary for memory sharing?
          
     But I don't think my box confront with OOM, since I've been periodically
check memory through "xm info", it shows about 10G free memory. Also,
this is the first time the test run into this bug.
 
     Could you let me know how you set up memory sharing scenario?

 
> Date: Mon, 17 Jan 2011 17:02:02 +0800
> Subject: Re: [PATCH] mem_sharing: fix race condition of nominate and unshare
> From: juihaochiang@xxxxxxxxx
> To: tinnycloud@xxxxxxxxxxx
> CC: xen-devel@xxxxxxxxxxxxxxxxxxx; tim.deegan@xxxxxxxxxx
>
> Hi, tinnycloud:
>
> Do you have xenpaging tools running properly?
> I haven't gone through that one, but it seems you have run out of memory.
> When this case happens, mem_sharing will request memory to the
> xenpaging daemon, which tends to page out and free some memory.
> Otherwise, the allocation would fail.
> Is this your scenario?
>
> Bests,
> Jui-Hao
>
> 2011/1/17 MaoXiaoyun <tinnycloud@xxxxxxxxxxx>:
> > Another failure on BUG() in mem_sharing_alloc_page()
> >
> >  memset(&req, 0, sizeof(req));
> >  if(must_succeed)
> >     {
> &g t;         /* We do not support 'must_succeed' any more. External operations
> > such
> >          * as grant table mappings may fail with OOM condition!
> >          */
> >         BUG();===================>bug here
> >     }
> >     else
> >     {
> >         /* All foreign attempts to unshare pages should be handled through
> >          * 'must_succeed' case. */
> >         ASSERT(v->domain->domain_id == d->domain_id);
> >         vcpu_pause_nosync(v);
> >         req.flags |= MEM_EVENT_ FLAG_VCPU_PAUSED;
> >     }
> >

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