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Date: Mon, 15 Sep 2014 12:24:27 -0700 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Li Zhong <zhong@...ux.vnet.ibm.com>, Naoya Horiguchi <n-horiguchi@...jp.nec.com>, David Rientjes <rientjes@...gle.com>, Andrew Morton <akpm@...ux-foundation.org>, Linus Torvalds <torvalds@...ux-foundation.org> Subject: [PATCH 3.16 028/158] mm: fix potential infinite loop in dissolve_free_huge_pages() 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Li Zhong <zhong@...ux.vnet.ibm.com> commit d0177639310d23c7739500df3c6ce6fdfe34acec upstream. It is possible for some platforms, such as powerpc to set HPAGE_SHIFT to 0 to indicate huge pages not supported. When this is the case, hugetlbfs could be disabled during boot time: hugetlbfs: disabling because there are no supported hugepage sizes Then in dissolve_free_huge_pages(), order is kept maximum (64 for 64bits), and the for loop below won't end: for (pfn = start_pfn; pfn < end_pfn; pfn += 1 << order) As suggested by Naoya, below fix checks hugepages_supported() before calling dissolve_free_huge_pages(). [rientjes@...gle.com: no legitimate reason to call dissolve_free_huge_pages() when !hugepages_supported()] Signed-off-by: Li Zhong <zhong@...ux.vnet.ibm.com> Acked-by: Naoya Horiguchi <n-horiguchi@...jp.nec.com> Acked-by: David Rientjes <rientjes@...gle.com> Signed-off-by: David Rientjes <rientjes@...gle.com> Signed-off-by: Andrew Morton <akpm@...ux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org> --- mm/hugetlb.c | 3 +++ 1 file changed, 3 insertions(+) --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1089,6 +1089,9 @@ void dissolve_free_huge_pages(unsigned l unsigned long pfn; struct hstate *h; + if (!hugepages_supported()) + return; + /* Set scan step to minimum hugepage size */ for_each_hstate(h) if (order > huge_page_order(h)) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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