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| author | Nishanth Aravamudan <nacc@linux.vnet.ibm.com> | 2014-05-06 12:50:00 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-10-09 12:21:27 -0700 |
| commit | de1fc405fbc586005607e51599da5997463fbefc (patch) | |
| tree | b2d8bd964d934eb1103fd023e9cdb9b346da0891 /include | |
| parent | 04ceeee9bb02eabbaaf14c0d0dc759caa60de230 (diff) | |
| download | linux-stable-de1fc405fbc586005607e51599da5997463fbefc.tar.gz linux-stable-de1fc405fbc586005607e51599da5997463fbefc.tar.bz2 linux-stable-de1fc405fbc586005607e51599da5997463fbefc.zip | |
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 <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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/hugetlb.h | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index bd1e9bcec547..42b05c4c53e5 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -400,6 +400,16 @@ static inline spinlock_t *huge_pte_lockptr(struct hstate *h, return &mm->page_table_lock; } +static inline bool hugepages_supported(void) +{ + /* + * Some platform decide whether they support huge pages at boot + * time. On these, such as powerpc, HPAGE_SHIFT is set to 0 when + * there is no such support + */ + return HPAGE_SHIFT != 0; +} + #else /* CONFIG_HUGETLB_PAGE */ struct hstate {}; #define alloc_huge_page_node(h, nid) NULL |