Hello Naoya Horiguchi,
The patch c8721bbbdd36: "mm: memory-hotplug: enable memory hotplug to
handle hugepage" from Sep 11, 2013, leads to the following static
checker warning:
mm/hugetlb.c:1203 dissolve_free_huge_pages()
warn: potential right shift more than type allows '9,18,64'
mm/hugetlb.c
1189 void dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn)
1190 {
1191 unsigned int order = 8 * sizeof(void *);
^^^^^^^^^^^^^^^^^^
Let's say order is 64.
1192 unsigned long pfn;
1193 struct hstate *h;
1194
1195 if (!hugepages_supported())
1196 return;
1197
1198 /* Set scan step to minimum hugepage size */
1199 for_each_hstate(h)
1200 if (order > huge_page_order(h))
1201 order = huge_page_order(h);
1202 VM_BUG_ON(!IS_ALIGNED(start_pfn, 1 << order));
1203 for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order)
^^^^^^^^^^
1 << 64 is undefined but let's say it's zero because that's normal for
GCC. This is an endless loop.
1204 dissolve_free_huge_page(pfn_to_page(pfn));
1205 }
regards,
dan carpenter
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