Re: [xl] a fault happens on pv domain reboot

[Sergey Tovpeko <tsv.devel@gmail.com>]

The mlock issue isn't my case. I mean the patch didn't solve the problem.
The mentioned mlock returned success with the first iteration.

I thought below patch (trick) solves the issue, but it only decreases 
the probability of the bug.

diff -r 458589ad3793 tools/libxl/xl_cmdimpl.c
--- a/tools/libxl/xl_cmdimpl.c  Tue Jun 01 07:06:50 2010 +0100
+++ b/tools/libxl/xl_cmdimpl.c  Wed Jun 02 16:57:59 2010 +0400
@@ -1159,6 +1159,15 @@
                             libxl_free_waiter(w2);
                             free(w1);
                             free(w2);
+                            while (1) {
+                                struct libxl_dominfo info_t;
+                                if (libxl_domain_info(&ctx, &info_t, 
domid))
+                                    break;
+                                sleep(1);
+                            }
 
                             LOG("Done. Rebooting now");
                             goto start;
                         }


> Stefano Stabellini writes ("Re: [Xen-devel] [xl] a fault happens on pv domain reboot"):
>   
>> That means that xc_domain_getinfolist failed with EAGAIN, the reason
>> seems to be that mlock can actually failed with EAGAIN but we don't do
>> anything about it in libxc.
>> If mlock returns EAGAIN we should make sure that the pages are actually
>> available in RAM and try again.
>>     
>
> So, on that note, could you please try this patch ?
>
> Ian.
>
> diff -r 267ecb2ee5bf tools/libxc/xc_acm.c
> --- a/tools/libxc/xc_acm.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_acm.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -83,7 +83,7 @@
>  
>      hypercall.op = __HYPERVISOR_xsm_op;
>      hypercall.arg[0] = (unsigned long)&acmctl;
> -    if ( lock_pages(&acmctl, sizeof(acmctl)) != 0)
> +    if ( xc_lock_pages(xch, &acmctl, sizeof(acmctl)) != 0)
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          return -EFAULT;
> diff -r 267ecb2ee5bf tools/libxc/xc_cpupool.c
> --- a/tools/libxc/xc_cpupool.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_cpupool.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -71,7 +71,7 @@
>          set_xen_guest_handle(sysctl.u.cpupool_op.cpumap.bitmap, local);
>          sysctl.u.cpupool_op.cpumap.nr_cpus = sizeof(info->cpumap) * 8;
>  
> -        if ( (err = lock_pages(local, sizeof(local))) != 0 )
> +        if ( (err = xc_lock_pages(xch, local, sizeof(local))) != 0 )
>          {
>              PERROR("Could not lock memory for Xen hypercall");
>              break;
> @@ -147,7 +147,7 @@
>      set_xen_guest_handle(sysctl.u.cpupool_op.cpumap.bitmap, local);
>      sysctl.u.cpupool_op.cpumap.nr_cpus = sizeof(*cpumap) * 8;
>  
> -    if ( (err = lock_pages(local, sizeof(local))) != 0 )
> +    if ( (err = xc_lock_pages(xch, local, sizeof(local))) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          return err;
> diff -r 267ecb2ee5bf tools/libxc/xc_domain.c
> --- a/tools/libxc/xc_domain.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_domain.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -80,7 +80,7 @@
>      arg.domain_id = domid;
>      arg.reason = reason;
>  
> -    if ( lock_pages(&arg, sizeof(arg)) != 0 )
> +    if ( xc_lock_pages(xch, &arg, sizeof(arg)) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out1;
> @@ -119,7 +119,7 @@
>  
>      domctl.u.vcpuaffinity.cpumap.nr_cpus = cpusize * 8;
>      
> -    if ( lock_pages(local, cpusize) != 0 )
> +    if ( xc_lock_pages(xch, local, cpusize) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out;
> @@ -158,7 +158,7 @@
>      set_xen_guest_handle(domctl.u.vcpuaffinity.cpumap.bitmap, local);
>      domctl.u.vcpuaffinity.cpumap.nr_cpus = cpusize * 8;
>      
> -    if ( lock_pages(local, sizeof(local)) != 0 )
> +    if ( xc_lock_pages(xch, local, sizeof(local)) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out;
> @@ -243,7 +243,7 @@
>      int ret = 0;
>      DECLARE_SYSCTL;
>  
> -    if ( lock_pages(info, max_domains*sizeof(xc_domaininfo_t)) != 0 )
> +    if ( xc_lock_pages(xch, info, max_domains*sizeof(xc_domaininfo_t)) != 0 )
>          return -1;
>  
>      sysctl.cmd = XEN_SYSCTL_getdomaininfolist;
> @@ -276,7 +276,7 @@
>      set_xen_guest_handle(domctl.u.hvmcontext.buffer, ctxt_buf);
>  
>      if ( ctxt_buf ) 
> -        if ( (ret = lock_pages(ctxt_buf, size)) != 0 )
> +        if ( (ret = xc_lock_pages(xch, ctxt_buf, size)) != 0 )
>              return ret;
>  
>      ret = do_domctl(xch, &domctl);
> @@ -308,7 +308,7 @@
>      domctl.u.hvmcontext_partial.instance = instance;
>      set_xen_guest_handle(domctl.u.hvmcontext_partial.buffer, ctxt_buf);
>  
> -    if ( (ret = lock_pages(ctxt_buf, size)) != 0 )
> +    if ( (ret = xc_lock_pages(xch, ctxt_buf, size)) != 0 )
>          return ret;
>      
>      ret = do_domctl(xch, &domctl);
> @@ -333,7 +333,7 @@
>      domctl.u.hvmcontext.size = size;
>      set_xen_guest_handle(domctl.u.hvmcontext.buffer, ctxt_buf);
>  
> -    if ( (ret = lock_pages(ctxt_buf, size)) != 0 )
> +    if ( (ret = xc_lock_pages(xch, ctxt_buf, size)) != 0 )
>          return ret;
>  
>      ret = do_domctl(xch, &domctl);
> @@ -358,7 +358,7 @@
>      set_xen_guest_handle(domctl.u.vcpucontext.ctxt, &ctxt->c);
>  
>      
> -    if ( (rc = lock_pages(ctxt, sz)) != 0 )
> +    if ( (rc = xc_lock_pages(xch, ctxt, sz)) != 0 )
>          return rc;
>      rc = do_domctl(xch, &domctl);
>      unlock_pages(ctxt, sz);
> @@ -446,7 +446,8 @@
>  
>      set_xen_guest_handle(fmap.map.buffer, &e820);
>  
> -    if ( lock_pages(&fmap, sizeof(fmap)) || lock_pages(&e820, sizeof(e820)) )
> +    if ( xc_lock_pages(xch, &fmap, sizeof(fmap)) ||
> +         xc_lock_pages(xch, &e820, sizeof(e820)) )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          rc = -1;
> @@ -522,7 +523,7 @@
>      domctl.cmd = XEN_DOMCTL_gettscinfo;
>      domctl.domain = (domid_t)domid;
>      set_xen_guest_handle(domctl.u.tsc_info.out_info, &info);
> -    if ( (rc = lock_pages(&info, sizeof(info))) != 0 )
> +    if ( (rc = xc_lock_pages(xch, &info, sizeof(info))) != 0 )
>          return rc;
>      rc = do_domctl(xch, &domctl);
>      if ( rc == 0 )
> @@ -807,7 +808,7 @@
>      domctl.u.vcpucontext.vcpu = vcpu;
>      set_xen_guest_handle(domctl.u.vcpucontext.ctxt, &ctxt->c);
>  
> -    if ( (rc = lock_pages(ctxt, sz)) != 0 )
> +    if ( (rc = xc_lock_pages(xch, ctxt, sz)) != 0 )
>          return rc;
>      rc = do_domctl(xch, &domctl);
>      
> @@ -875,7 +876,7 @@
>      arg.domid = dom;
>      arg.index = param;
>      arg.value = value;
> -    if ( lock_pages(&arg, sizeof(arg)) != 0 )
> +    if ( xc_lock_pages(handle, &arg, sizeof(arg)) != 0 )
>          return -1;
>      rc = do_xen_hypercall(handle, &hypercall);
>      unlock_pages(&arg, sizeof(arg));
> @@ -893,7 +894,7 @@
>      hypercall.arg[1] = (unsigned long)&arg;
>      arg.domid = dom;
>      arg.index = param;
> -    if ( lock_pages(&arg, sizeof(arg)) != 0 )
> +    if ( xc_lock_pages(handle, &arg, sizeof(arg)) != 0 )
>          return -1;
>      rc = do_xen_hypercall(handle, &hypercall);
>      unlock_pages(&arg, sizeof(arg));
> @@ -946,7 +947,7 @@
>  
>      set_xen_guest_handle(domctl.u.get_device_group.sdev_array, sdev_array);
>  
> -    if ( lock_pages(sdev_array, max_sdevs * sizeof(*sdev_array)) != 0 )
> +    if ( xc_lock_pages(xch, sdev_array, max_sdevs * sizeof(*sdev_array)) != 0 )
>      {
>          PERROR("Could not lock memory for xc_get_device_group");
>          return -ENOMEM;
> diff -r 267ecb2ee5bf tools/libxc/xc_domain_restore.c
> --- a/tools/libxc/xc_domain_restore.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_domain_restore.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -1451,7 +1451,7 @@
>      memset(region_mfn, 0,
>             ROUNDUP(MAX_BATCH_SIZE * sizeof(xen_pfn_t), PAGE_SHIFT)); 
>  
> -    if ( lock_pages(region_mfn, sizeof(xen_pfn_t) * MAX_BATCH_SIZE) )
> +    if ( xc_lock_pages(xch, region_mfn, sizeof(xen_pfn_t) * MAX_BATCH_SIZE) )
>      {
>          PERROR("Could not lock region_mfn");
>          goto out;
> @@ -1801,7 +1801,7 @@
>          }
>      }
>  
> -    if ( lock_pages(&ctxt, sizeof(ctxt)) )
> +    if ( xc_lock_pages(xch, &ctxt, sizeof(ctxt)) )
>      {
>          PERROR("Unable to lock ctxt");
>          return 1;
> diff -r 267ecb2ee5bf tools/libxc/xc_domain_save.c
> --- a/tools/libxc/xc_domain_save.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_domain_save.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -1032,14 +1032,14 @@
>  
>      memset(to_send, 0xff, BITMAP_SIZE);
>  
> -    if ( lock_pages(to_send, BITMAP_SIZE) )
> +    if ( xc_lock_pages(xch, to_send, BITMAP_SIZE) )
>      {
>          PERROR("Unable to lock to_send");
>          return 1;
>      }
>  
>      /* (to fix is local only) */
> -    if ( lock_pages(to_skip, BITMAP_SIZE) )
> +    if ( xc_lock_pages(xch, to_skip, BITMAP_SIZE) )
>      {
>          PERROR("Unable to lock to_skip");
>          return 1;
> @@ -1077,7 +1077,7 @@
>      memset(pfn_type, 0,
>             ROUNDUP(MAX_BATCH_SIZE * sizeof(*pfn_type), PAGE_SHIFT));
>  
> -    if ( lock_pages(pfn_type, MAX_BATCH_SIZE * sizeof(*pfn_type)) )
> +    if ( xc_lock_pages(xch, pfn_type, MAX_BATCH_SIZE * sizeof(*pfn_type)) )
>      {
>          PERROR("Unable to lock pfn_type array");
>          goto out;
> diff -r 267ecb2ee5bf tools/libxc/xc_evtchn.c
> --- a/tools/libxc/xc_evtchn.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_evtchn.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -19,7 +19,7 @@
>      hypercall.arg[0] = cmd;
>      hypercall.arg[1] = (unsigned long)arg;
>  
> -    if ( lock_pages(arg, arg_size) != 0 )
> +    if ( xc_lock_pages(xch, arg, arg_size) != 0 )
>      {
>          PERROR("do_evtchn_op: arg lock failed");
>          goto out;
> diff -r 267ecb2ee5bf tools/libxc/xc_linux.c
> --- a/tools/libxc/xc_linux.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_linux.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -724,7 +724,7 @@
>      hypercall.arg[1] = (unsigned long)op;
>      hypercall.arg[2] = count;
>  
> -    if ( lock_pages(op, count* op_size) != 0 )
> +    if ( xc_lock_pages(xch, op, count* op_size) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out1;
> @@ -776,7 +776,7 @@
>      *gnt_num = query.nr_frames * (PAGE_SIZE / sizeof(grant_entry_v1_t) );
>  
>      frame_list = malloc(query.nr_frames * sizeof(unsigned long));
> -    if ( !frame_list || lock_pages(frame_list,
> +    if ( !frame_list || xc_lock_pages(xch, frame_list,
>                                     query.nr_frames * sizeof(unsigned long)) )
>      {
>          ERROR("Alloc/lock frame_list in xc_gnttab_map_table\n");
> diff -r 267ecb2ee5bf tools/libxc/xc_misc.c
> --- a/tools/libxc/xc_misc.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_misc.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -28,7 +28,7 @@
>          sysctl.u.readconsole.incremental = incremental;
>      }
>  
> -    if ( (ret = lock_pages(buffer, nr_chars)) != 0 )
> +    if ( (ret = xc_lock_pages(xch, buffer, nr_chars)) != 0 )
>          return ret;
>  
>      if ( (ret = do_sysctl(xch, &sysctl)) == 0 )
> @@ -52,7 +52,7 @@
>      set_xen_guest_handle(sysctl.u.debug_keys.keys, keys);
>      sysctl.u.debug_keys.nr_keys = len;
>  
> -    if ( (ret = lock_pages(keys, len)) != 0 )
> +    if ( (ret = xc_lock_pages(xch, keys, len)) != 0 )
>          return ret;
>  
>      ret = do_sysctl(xch, &sysctl);
> @@ -140,7 +140,7 @@
>      DECLARE_HYPERCALL;
>  
>      mc->interface_version = XEN_MCA_INTERFACE_VERSION;
> -    if ( lock_pages(mc, sizeof(mc)) )
> +    if ( xc_lock_pages(xch, mc, sizeof(mc)) )
>      {
>          PERROR("Could not lock xen_mc memory");
>          return -EINVAL;
> @@ -213,7 +213,7 @@
>      sysctl.u.getcpuinfo.max_cpus = max_cpus; 
>      set_xen_guest_handle(sysctl.u.getcpuinfo.info, info); 
>  
> -    if ( (rc = lock_pages(info, max_cpus*sizeof(*info))) != 0 )
> +    if ( (rc = xc_lock_pages(xch, info, max_cpus*sizeof(*info))) != 0 )
>          return rc;
>  
>      rc = do_sysctl(xch, &sysctl);
> @@ -236,7 +236,7 @@
>      struct xen_hvm_set_pci_intx_level _arg, *arg = &_arg;
>      int rc;
>  
> -    if ( (rc = hcall_buf_prep((void **)&arg, sizeof(*arg))) != 0 )
> +    if ( (rc = hcall_buf_prep(xch, (void **)&arg, sizeof(*arg))) != 0 )
>      {
>          PERROR("Could not lock memory");
>          return rc;
> @@ -269,7 +269,7 @@
>      struct xen_hvm_set_isa_irq_level _arg, *arg = &_arg;
>      int rc;
>  
> -    if ( (rc = hcall_buf_prep((void **)&arg, sizeof(*arg))) != 0 )
> +    if ( (rc = hcall_buf_prep(xch, (void **)&arg, sizeof(*arg))) != 0 )
>      {
>          PERROR("Could not lock memory");
>          return rc;
> @@ -305,7 +305,7 @@
>      arg.link    = link;
>      arg.isa_irq = isa_irq;
>  
> -    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
> +    if ( (rc = xc_lock_pages(xch, &arg, sizeof(arg))) != 0 )
>      {
>          PERROR("Could not lock memory");
>          return rc;
> @@ -336,7 +336,7 @@
>      arg.nr        = nr;
>      set_xen_guest_handle(arg.dirty_bitmap, (uint8_t *)dirty_bitmap);
>  
> -    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
> +    if ( (rc = xc_lock_pages(xch, &arg, sizeof(arg))) != 0 )
>      {
>          PERROR("Could not lock memory");
>          return rc;
> @@ -364,7 +364,7 @@
>      arg.first_pfn = first_pfn;
>      arg.nr        = nr;
>  
> -    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
> +    if ( (rc = xc_lock_pages(xch, &arg, sizeof(arg))) != 0 )
>      {
>          PERROR("Could not lock memory");
>          return rc;
> @@ -393,7 +393,7 @@
>      arg.first_pfn    = first_pfn;
>      arg.nr           = nr;
>  
> -    if ( (rc = lock_pages(&arg, sizeof(arg))) != 0 )
> +    if ( (rc = xc_lock_pages(xch, &arg, sizeof(arg))) != 0 )
>      {
>          PERROR("Could not lock memory");
>          return rc;
> diff -r 267ecb2ee5bf tools/libxc/xc_offline_page.c
> --- a/tools/libxc/xc_offline_page.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_offline_page.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -57,7 +57,7 @@
>      if ( !status || (end < start) )
>          return -EINVAL;
>  
> -    if (lock_pages(status, sizeof(uint32_t)*(end - start + 1)))
> +    if (xc_lock_pages(xch, status, sizeof(uint32_t)*(end - start + 1)))
>      {
>          ERROR("Could not lock memory for xc_mark_page_online\n");
>          return -EINVAL;
> @@ -84,7 +84,7 @@
>      if ( !status || (end < start) )
>          return -EINVAL;
>  
> -    if (lock_pages(status, sizeof(uint32_t)*(end - start + 1)))
> +    if (xc_lock_pages(xch, status, sizeof(uint32_t)*(end - start + 1)))
>      {
>          ERROR("Could not lock memory for xc_mark_page_offline");
>          return -EINVAL;
> @@ -111,7 +111,7 @@
>      if ( !status || (end < start) )
>          return -EINVAL;
>  
> -    if (lock_pages(status, sizeof(uint32_t)*(end - start + 1)))
> +    if (xc_lock_pages(xch, status, sizeof(uint32_t)*(end - start + 1)))
>      {
>          ERROR("Could not lock memory for xc_query_page_offline_status\n");
>          return -EINVAL;
> @@ -277,7 +277,7 @@
>          minfo->pfn_type[i] = pfn_to_mfn(i, minfo->p2m_table,
>                                          minfo->guest_width);
>  
> -    if ( lock_pages(minfo->pfn_type, minfo->p2m_size * sizeof(*minfo->pfn_type)) )
> +    if ( xc_lock_pages(xch, minfo->pfn_type, minfo->p2m_size * sizeof(*minfo->pfn_type)) )
>      {
>          ERROR("Unable to lock pfn_type array");
>          goto failed;
> diff -r 267ecb2ee5bf tools/libxc/xc_pm.c
> --- a/tools/libxc/xc_pm.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_pm.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -57,11 +57,11 @@
>      if ( (ret = xc_pm_get_max_px(xch, cpuid, &max_px)) != 0)
>          return ret;
>  
> -    if ( (ret = lock_pages(pxpt->trans_pt, 
> +    if ( (ret = xc_lock_pages(xch, pxpt->trans_pt, 
>          max_px * max_px * sizeof(uint64_t))) != 0 )
>          return ret;
>  
> -    if ( (ret = lock_pages(pxpt->pt, 
> +    if ( (ret = xc_lock_pages(xch, pxpt->pt, 
>          max_px * sizeof(struct xc_px_val))) != 0 )
>      {
>          unlock_pages(pxpt->trans_pt, max_px * max_px * sizeof(uint64_t));
> @@ -132,11 +132,11 @@
>      if ( (ret = xc_pm_get_max_cx(xch, cpuid, &max_cx)) )
>          goto unlock_0;
>  
> -    if ( (ret = lock_pages(cxpt, sizeof(struct xc_cx_stat))) )
> +    if ( (ret = xc_lock_pages(xch, cxpt, sizeof(struct xc_cx_stat))) )
>          goto unlock_0;
> -    if ( (ret = lock_pages(cxpt->triggers, max_cx * sizeof(uint64_t))) )
> +    if ( (ret = xc_lock_pages(xch, cxpt->triggers, max_cx * sizeof(uint64_t))) )
>          goto unlock_1;
> -    if ( (ret = lock_pages(cxpt->residencies, max_cx * sizeof(uint64_t))) )
> +    if ( (ret = xc_lock_pages(xch, cxpt->residencies, max_cx * sizeof(uint64_t))) )
>          goto unlock_2;
>  
>      sysctl.cmd = XEN_SYSCTL_get_pmstat;
> @@ -199,13 +199,13 @@
>               (!user_para->scaling_available_governors) )
>              return -EINVAL;
>  
> -        if ( (ret = lock_pages(user_para->affected_cpus,
> +        if ( (ret = xc_lock_pages(xch, user_para->affected_cpus,
>                                 user_para->cpu_num * sizeof(uint32_t))) )
>              goto unlock_1;
> -        if ( (ret = lock_pages(user_para->scaling_available_frequencies,
> +        if ( (ret = xc_lock_pages(xch, user_para->scaling_available_frequencies,
>                                 user_para->freq_num * sizeof(uint32_t))) )
>              goto unlock_2;
> -        if ( (ret = lock_pages(user_para->scaling_available_governors,
> +        if ( (ret = xc_lock_pages(xch, user_para->scaling_available_governors,
>                   user_para->gov_num * CPUFREQ_NAME_LEN * sizeof(char))) )
>              goto unlock_3;
>  
> diff -r 267ecb2ee5bf tools/libxc/xc_private.c
> --- a/tools/libxc/xc_private.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_private.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -174,7 +174,7 @@
>  
>  #ifdef __sun__
>  
> -int lock_pages(void *addr, size_t len) { return 0; }
> +int xc_lock_pages(xc_interface *xch, void *addr, size_t len) { return 0; }
>  void unlock_pages(void *addr, size_t len) { }
>  
>  int hcall_buf_prep(void **addr, size_t len) { return 0; }
> @@ -182,13 +182,40 @@
>  
>  #else /* !__sun__ */
>  
> -int lock_pages(void *addr, size_t len)
> +int xc_lock_pages(xc_interface *xch, void *addr, size_t len)
>  {
>        int e;
>        void *laddr = (void *)((unsigned long)addr & PAGE_MASK);
>        size_t llen = (len + ((unsigned long)addr - (unsigned long)laddr) +
>                       PAGE_SIZE - 1) & PAGE_MASK;
> -      e = mlock(laddr, llen);
> +      size_t offset;
> +      int iterations = 0;
> +      int dummy;
> +
> +      for (;;) {
> +          e = mlock(laddr, llen);
> +          if (!e) {
> +              if (iterations > 5)
> +                  DBGPRINTF("mlock (libxc_lock_pages) (len=%zu)"
> +                            " took %d iterations", len, iterations);
> +              return 0;
> +          }
> +          if (errno != EAGAIN) {
> +              PERROR("mlock (libxc_lock_pages) failed (len=%zu)", len);
> +              return e;
> +          }
> +          if (++iterations > 100) {
> +              ERROR("mlock (libxc_lock_pages) too much EAGAIN (len=%zu)", len);
> +              return -1;
> +          }
> +          if (iterations > 10) {
> +              /* max total time: 1/2 * 100 * 2000 us = 1 second */
> +              usleep(iterations * 2000);
> +          }
> +          for (offset = 0; offset < len; offset += PAGE_SIZE) {
> +              dummy = ((volatile unsigned char*)addr)[offset];
> +          }
> +      }
>        return e;
>  }
>  
> @@ -230,7 +257,7 @@
>      pthread_key_create(&hcall_buf_pkey, _xc_clean_hcall_buf);
>  }
>  
> -int hcall_buf_prep(void **addr, size_t len)
> +int hcall_buf_prep(xc_interface *xch, void **addr, size_t len)
>  {
>      struct hcall_buf *hcall_buf;
>  
> @@ -248,7 +275,7 @@
>      if ( !hcall_buf->buf )
>      {
>          hcall_buf->buf = xc_memalign(PAGE_SIZE, PAGE_SIZE);
> -        if ( !hcall_buf->buf || lock_pages(hcall_buf->buf, PAGE_SIZE) )
> +        if ( !hcall_buf->buf || xc_lock_pages(xch, hcall_buf->buf, PAGE_SIZE) )
>          {
>              free(hcall_buf->buf);
>              hcall_buf->buf = NULL;
> @@ -265,7 +292,7 @@
>      }
>  
>   out:
> -    return lock_pages(*addr, len);
> +    return xc_lock_pages(xch, *addr, len);
>  }
>  
>  void hcall_buf_release(void **addr, size_t len)
> @@ -307,7 +334,7 @@
>      DECLARE_HYPERCALL;
>      long ret = -EINVAL;
>  
> -    if ( hcall_buf_prep((void **)&op, nr_ops*sizeof(*op)) != 0 )
> +    if ( hcall_buf_prep(xch, (void **)&op, nr_ops*sizeof(*op)) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out1;
> @@ -341,7 +368,7 @@
>      hypercall.arg[2] = 0;
>      hypercall.arg[3] = mmu->subject;
>  
> -    if ( lock_pages(mmu->updates, sizeof(mmu->updates)) != 0 )
> +    if ( xc_lock_pages(xch, mmu->updates, sizeof(mmu->updates)) != 0 )
>      {
>          PERROR("flush_mmu_updates: mmu updates lock_pages failed");
>          err = 1;
> @@ -408,14 +435,14 @@
>      case XENMEM_increase_reservation:
>      case XENMEM_decrease_reservation:
>      case XENMEM_populate_physmap:
> -        if ( lock_pages(reservation, sizeof(*reservation)) != 0 )
> +        if ( xc_lock_pages(xch, reservation, sizeof(*reservation)) != 0 )
>          {
>              PERROR("Could not lock");
>              goto out1;
>          }
>          get_xen_guest_handle(extent_start, reservation->extent_start);
>          if ( (extent_start != NULL) &&
> -             (lock_pages(extent_start,
> +             (xc_lock_pages(xch, extent_start,
>                      reservation->nr_extents * sizeof(xen_pfn_t)) != 0) )
>          {
>              PERROR("Could not lock");
> @@ -424,13 +451,13 @@
>          }
>          break;
>      case XENMEM_machphys_mfn_list:
> -        if ( lock_pages(xmml, sizeof(*xmml)) != 0 )
> +        if ( xc_lock_pages(xch, xmml, sizeof(*xmml)) != 0 )
>          {
>              PERROR("Could not lock");
>              goto out1;
>          }
>          get_xen_guest_handle(extent_start, xmml->extent_start);
> -        if ( lock_pages(extent_start,
> +        if ( xc_lock_pages(xch, extent_start,
>                     xmml->max_extents * sizeof(xen_pfn_t)) != 0 )
>          {
>              PERROR("Could not lock");
> @@ -439,7 +466,7 @@
>          }
>          break;
>      case XENMEM_add_to_physmap:
> -        if ( lock_pages(arg, sizeof(struct xen_add_to_physmap)) )
> +        if ( xc_lock_pages(xch, arg, sizeof(struct xen_add_to_physmap)) )
>          {
>              PERROR("Could not lock");
>              goto out1;
> @@ -448,7 +475,7 @@
>      case XENMEM_current_reservation:
>      case XENMEM_maximum_reservation:
>      case XENMEM_maximum_gpfn:
> -        if ( lock_pages(arg, sizeof(domid_t)) )
> +        if ( xc_lock_pages(xch, arg, sizeof(domid_t)) )
>          {
>              PERROR("Could not lock");
>              goto out1;
> @@ -456,7 +483,7 @@
>          break;
>      case XENMEM_set_pod_target:
>      case XENMEM_get_pod_target:
> -        if ( lock_pages(arg, sizeof(struct xen_pod_target)) )
> +        if ( xc_lock_pages(xch, arg, sizeof(struct xen_pod_target)) )
>          {
>              PERROR("Could not lock");
>              goto out1;
> @@ -535,7 +562,7 @@
>      memset(pfn_buf, 0, max_pfns * sizeof(*pfn_buf));
>  #endif
>  
> -    if ( lock_pages(pfn_buf, max_pfns * sizeof(*pfn_buf)) != 0 )
> +    if ( xc_lock_pages(xch, pfn_buf, max_pfns * sizeof(*pfn_buf)) != 0 )
>      {
>          PERROR("xc_get_pfn_list: pfn_buf lock failed");
>          return -1;
> @@ -618,7 +645,7 @@
>          break;
>      }
>  
> -    if ( (argsize != 0) && (lock_pages(arg, argsize) != 0) )
> +    if ( (argsize != 0) && (xc_lock_pages(xch, arg, argsize) != 0) )
>      {
>          PERROR("Could not lock memory for version hypercall");
>          return -ENOMEM;
> diff -r 267ecb2ee5bf tools/libxc/xc_private.h
> --- a/tools/libxc/xc_private.h	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_private.h	Tue Jun 01 17:54:51 2010 +0100
> @@ -85,10 +85,10 @@
>  
>  void *xc_memalign(size_t alignment, size_t size);
>  
> -int lock_pages(void *addr, size_t len);
> +int xc_lock_pages(xc_interface*, void *addr, size_t len);
>  void unlock_pages(void *addr, size_t len);
>  
> -int hcall_buf_prep(void **addr, size_t len);
> +int hcall_buf_prep(xc_interface*, void **addr, size_t len);
>  void hcall_buf_release(void **addr, size_t len);
>  
>  static inline void safe_munlock(const void *addr, size_t len)
> @@ -117,7 +117,7 @@
>  
>      DECLARE_HYPERCALL;
>  
> -    if ( hcall_buf_prep(&op, len) != 0 )
> +    if ( hcall_buf_prep(xch, &op, len) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out1;
> @@ -145,7 +145,7 @@
>      int ret = -1;
>      DECLARE_HYPERCALL;
>  
> -    if ( hcall_buf_prep((void **)&domctl, sizeof(*domctl)) != 0 )
> +    if ( hcall_buf_prep(xch, (void **)&domctl, sizeof(*domctl)) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out1;
> @@ -174,7 +174,7 @@
>      int ret = -1;
>      DECLARE_HYPERCALL;
>  
> -    if ( hcall_buf_prep((void **)&sysctl, sizeof(*sysctl)) != 0 )
> +    if ( hcall_buf_prep(xch, (void **)&sysctl, sizeof(*sysctl)) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out1;
> diff -r 267ecb2ee5bf tools/libxc/xc_resume.c
> --- a/tools/libxc/xc_resume.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_resume.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -180,7 +180,7 @@
>          goto out;
>      }
>  
> -    if ( lock_pages(&ctxt, sizeof(ctxt)) )
> +    if ( xc_lock_pages(xch, &ctxt, sizeof(ctxt)) )
>      {
>          ERROR("Unable to lock ctxt");
>          goto out;
> diff -r 267ecb2ee5bf tools/libxc/xc_tbuf.c
> --- a/tools/libxc/xc_tbuf.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_tbuf.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -120,7 +120,7 @@
>      set_xen_guest_handle(sysctl.u.tbuf_op.cpu_mask.bitmap, bytemap);
>      sysctl.u.tbuf_op.cpu_mask.nr_cpus = sizeof(bytemap) * 8;
>  
> -    if ( lock_pages(&bytemap, sizeof(bytemap)) != 0 )
> +    if ( xc_lock_pages(xch, &bytemap, sizeof(bytemap)) != 0 )
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          goto out;
> diff -r 267ecb2ee5bf tools/libxc/xc_tmem.c
> --- a/tools/libxc/xc_tmem.c	Tue Jun 01 14:25:59 2010 +0100
> +++ b/tools/libxc/xc_tmem.c	Tue Jun 01 17:54:51 2010 +0100
> @@ -14,7 +14,7 @@
>  
>      hypercall.op = __HYPERVISOR_tmem_op;
>      hypercall.arg[0] = (unsigned long)op;
> -    if (lock_pages(op, sizeof(*op)) != 0)
> +    if (xc_lock_pages(xch, op, sizeof(*op)) != 0)
>      {
>          PERROR("Could not lock memory for Xen hypercall");
>          return -EFAULT;
> @@ -52,7 +52,7 @@
>      op.u.ctrl.arg3 = arg3;
>  
>      if (subop == TMEMC_LIST) {
> -        if ((arg1 != 0) && (lock_pages(buf, arg1) != 0))
> +        if ((arg1 != 0) && (xc_lock_pages(xch, buf, arg1) != 0))
>          {
>              PERROR("Could not lock memory for Xen hypercall");
>              return -ENOMEM;
>