From: Nishanth Aravamudan Date: Tue, 6 May 2014 19:50:00 +0000 (-0700) Subject: hugetlb: ensure hugepage access is denied if hugepages are not supported X-Git-Tag: v3.2.81~26 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=27468d24c717327232b7de5bc7762691cd44ae43;p=pandora-kernel.git hugetlb: ensure hugepage access is denied if hugepages are not supported commit 457c1b27ed56ec472d202731b12417bff023594a upstream. Currently, I am seeing the following when I `mount -t hugetlbfs /none /dev/hugetlbfs`, and then simply do a `ls /dev/hugetlbfs`. I think it's related to the fact that hugetlbfs is properly not correctly setting itself up in this state?: Unable to handle kernel paging request for data at address 0x00000031 Faulting instruction address: 0xc000000000245710 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 NUMA pSeries .... In KVM guests on Power, in a guest not backed by hugepages, we see the following: AnonHugePages: 0 kB HugePages_Total: 0 HugePages_Free: 0 HugePages_Rsvd: 0 HugePages_Surp: 0 Hugepagesize: 64 kB HPAGE_SHIFT == 0 in this configuration, which indicates that hugepages are not supported at boot-time, but this is only checked in hugetlb_init(). Extract the check to a helper function, and use it in a few relevant places. This does make hugetlbfs not supported (not registered at all) in this environment. I believe this is fine, as there are no valid hugepages and that won't change at runtime. [akpm@linux-foundation.org: use pr_info(), per Mel] [akpm@linux-foundation.org: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan Reviewed-by: Aneesh Kumar K.V Acked-by: Mel Gorman Cc: Randy Dunlap Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds [bwh: Backported to 3.2: - Drop changes to hugetlb_show_meminfo() - Adjust context] Signed-off-by: Ben Hutchings --- Reading git-diff-tree failed