From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Li Zhong , Naoya Horiguchi , David Rientjes , Andrew Morton , Linus Torvalds Subject: [PATCH 3.16 028/158] mm: fix potential infinite loop in dissolve_free_huge_pages() Date: Mon, 15 Sep 2014 12:24:27 -0700 Message-Id: <20140915192543.730250398@linuxfoundation.org> In-Reply-To: <20140915192542.872134685@linuxfoundation.org> References: <20140915192542.872134685@linuxfoundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: 3.16-stable review patch. If anyone has any objections, please let me know. ------------------ From: Li Zhong 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@google.com: no legitimate reason to call dissolve_free_huge_pages() when !hugepages_supported()] Signed-off-by: Li Zhong Acked-by: Naoya Horiguchi Acked-by: David Rientjes Signed-off-by: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman --- 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))