[Xen-changelog] [xen master] page_alloc: clear nr_bootmem_regions in end_boot_allocator()

[patchbot@xxxxxxx]

commit 5fcf1c2516d253011b7c1001fe6a82e6c293f708
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Feb 7 14:32:05 2017 +0100
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Feb 7 14:32:05 2017 +0100

    page_alloc: clear nr_bootmem_regions in end_boot_allocator()
    
    ... to make alloc_boot_pages() fail for late callers. Don't rely on
    reaching the BOOT_BUG_ON(1) near the end of that function though, but
    instead make this situation easier to distinguish from actual
    allocation failures by adding an explicit check.
    
    While there, make the iteration variable unsigned and guard against
    underflow.
    
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
---
 xen/common/page_alloc.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/xen/common/page_alloc.c b/xen/common/page_alloc.c
index ae2476d..915e1f7 100644
--- a/xen/common/page_alloc.c
+++ b/xen/common/page_alloc.c
@@ -329,13 +329,16 @@ unsigned long __init alloc_boot_pages(
     unsigned long nr_pfns, unsigned long pfn_align)
 {
     unsigned long pg, _e;
-    int i;
+    unsigned int i = nr_bootmem_regions;
 
-    for ( i = nr_bootmem_regions - 1; i >= 0; i-- )
+    BOOT_BUG_ON(!nr_bootmem_regions);
+
+    while ( i-- )
     {
         struct bootmem_region *r = &bootmem_region_list[i];
+
         pg = (r->e - nr_pfns) & ~(pfn_align - 1);
-        if ( pg < r->s )
+        if ( pg >= r->e || pg < r->s )
             continue;
 
 #if defined(CONFIG_X86) && !defined(NDEBUG)
@@ -1352,6 +1355,7 @@ void __init end_boot_allocator(void)
         if ( r->s < r->e )
             init_heap_pages(mfn_to_page(r->s), r->e - r->s);
     }
+    nr_bootmem_regions = 0;
     init_heap_pages(virt_to_page(bootmem_region_list), 1);
 
     if ( !dma_bitsize && (num_online_nodes() > 1) )
--
generated by git-patchbot for /home/xen/git/xen.git#master

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