linux/include
Nishanth Aravamudan 457c1b27ed hugetlb: ensure hugepage access is denied if hugepages are not supported
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 <nacc@linux.vnet.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-05-06 13:04:58 -07:00
..
acpi IOMMU Upates for Linux v3.15 2014-04-05 18:46:26 -07:00
asm-generic - vexpress platform clocks initialisation moved earlier following the 2014-05-04 14:34:50 -07:00
clocksource
crypto crypto: export NULL algorithms defines 2014-03-21 21:54:26 +08:00
drm Merge branch 'drm-next-3.15-wip' of git://people.freedesktop.org/~deathsimple/linux into drm-next 2014-04-19 11:16:02 +10:00
dt-bindings dt: tegra: remove non-existent clock IDs 2014-04-24 15:37:08 +02:00
keys
kvm
linux hugetlb: ensure hugepage access is denied if hugepages are not supported 2014-05-06 13:04:58 -07:00
math-emu
media [media] rc-core: remove generic scancode filter 2014-04-06 11:30:29 -03:00
memory
misc
net vsock: Make transport the proto owner 2014-05-05 13:13:50 -04:00
pcmcia
ras
rdma Merge branches 'core', 'cxgb4', 'ip-roce', 'iser', 'misc', 'mlx4', 'nes', 'ocrdma', 'qib', 'sgwrapper', 'srp' and 'usnic' into for-next 2014-04-03 08:30:17 -07:00
rxrpc
scsi scsi: Make sure cmd_flags are 64-bit 2014-04-09 20:26:20 -06:00
sound ALSA: cs8427: separate HW initialization 2014-04-03 14:59:48 +02:00
target target/sbc: Add sbc_dif_read_strip software emulation 2014-04-07 01:48:57 -07:00
trace Fix: tracing: use 'E' instead of 'X' for unsigned module tain flag 2014-04-23 13:56:51 +09:30
uapi fuse: add renameat2 support 2014-04-28 16:43:44 +02:00
video fbdev changes for 3.15 (OMAP) 2014-04-07 10:47:51 -07:00
xen xen/acpi-processor: fix enabling interrupts on syscore_resume 2014-03-18 14:40:20 +00:00
Kbuild