Re: [Xen-devel] xen/pvh linux: Use ballooning to allocate grant table pages

[Dan Carpenter <dan.carpenter@xxxxxxxxxx>]

Hello Mukesh Rathor,

The patch 40f633eb0def: "xen/pvh linux: Use ballooning to allocate
grant table pages" from Jan 31, 2013, leads to the following Sparse
warning: "drivers/xen/grant-table.c:1095:28: error: bad constant
        expression"

drivers/xen/grant-table.c
  1092  static int xlated_setup_gnttab_pages(int numpages, void **addr)
  1093  {
  1094          int i, rc;
  1095          unsigned long pfns[numpages];
  1096          struct page *pages[numpages];
                                   ^^^^^^^^
Because the kernel uses an 8k stack if this is over 500 it will cause
a kernel crash.  It will crash before we reach 500 actually.  It looks
like typical values for this are around 4 so we're probably safe, but
it's still a bit nasty.

  1097  
  1098          rc = alloc_xenballooned_pages(numpages, pages, 0);
  1099          if (rc != 0) {
  1100                  pr_warn("%s Could not balloon alloc %d pfns rc:%d\n", 
__func__,

regards,
dan carpenter


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