Message ID | 20140403231413.GB17412@linux.vnet.ibm.com (mailing list archive) |
---|---|
State | Not Applicable |
Headers | show |
Nishanth Aravamudan <nacc@linux.vnet.ibm.com> writes: > 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. > > Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com> > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index d19b30a..cc8fcc7 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -1017,6 +1017,11 @@ static int __init init_hugetlbfs_fs(void) > int error; > int i; > > + if (!hugepages_supported()) { > + printk(KERN_ERR "hugetlbfs: Disabling because there are no supported hugepage sizes\n"); > + return -ENOTSUPP; > + } > + > error = bdi_init(&hugetlbfs_backing_dev_info); > if (error) > return error; > diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h > index 8c43cc4..0aea8de 100644 > --- a/include/linux/hugetlb.h > +++ b/include/linux/hugetlb.h > @@ -450,4 +450,14 @@ static inline spinlock_t *huge_pte_lock(struct hstate *h, > return ptl; > } > > +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; > +} > + > #endif /* _LINUX_HUGETLB_H */ > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index c01cb9f..1c99585 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -1949,11 +1949,7 @@ module_exit(hugetlb_exit); > > static int __init hugetlb_init(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 > - */ > - if (HPAGE_SHIFT == 0) > + if (!hugepages_supported()) > return 0; > > if (!size_to_hstate(default_hstate_size)) { > @@ -2069,6 +2065,9 @@ static int hugetlb_sysctl_handler_common(bool obey_mempolicy, > unsigned long tmp; > int ret; > > + if (!hugepages_supported()) > + return -ENOTSUPP; > + > tmp = h->max_huge_pages; > > if (write && h->order >= MAX_ORDER) > @@ -2122,6 +2121,9 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write, > unsigned long tmp; > int ret; > > + if (!hugepages_supported()) > + return -ENOTSUPP; > + > tmp = h->nr_overcommit_huge_pages; > > if (write && h->order >= MAX_ORDER) > @@ -2147,6 +2149,8 @@ out: > void hugetlb_report_meminfo(struct seq_file *m) > { > struct hstate *h = &default_hstate; > + if (!hugepages_supported()) > + return; > seq_printf(m, > "HugePages_Total: %5lu\n" > "HugePages_Free: %5lu\n" > @@ -2163,6 +2167,8 @@ void hugetlb_report_meminfo(struct seq_file *m) > int hugetlb_report_node_meminfo(int nid, char *buf) > { > struct hstate *h = &default_hstate; > + if (!hugepages_supported()) > + return 0; > return sprintf(buf, > "Node %d HugePages_Total: %5u\n" > "Node %d HugePages_Free: %5u\n" > @@ -2177,6 +2183,9 @@ void hugetlb_show_meminfo(void) > struct hstate *h; > int nid; > > + if (!hugepages_supported()) > + return; > + > for_each_node_state(nid, N_MEMORY) > for_each_hstate(h) > pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
On Thu, Apr 03, 2014 at 04:14:13PM -0700, Nishanth Aravamudan wrote: > 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. > > Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com> Acked-by: Mel Gorman <mgorman@suse.de> This patch looks ok but the changelog misses important information from the original report which is probably why it fell through the cracks. Add the fact that you encountered a problem during mount to the changelog and resend it directly to Andrew. This part from your original report; 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 .... It probably slipped through the cracks because from the changelog this looks like a minor formatting issue and not a functional fix. > > diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c > index d19b30a..cc8fcc7 100644 > --- a/fs/hugetlbfs/inode.c > +++ b/fs/hugetlbfs/inode.c > @@ -1017,6 +1017,11 @@ static int __init init_hugetlbfs_fs(void) > int error; > int i; > > + if (!hugepages_supported()) { > + printk(KERN_ERR "hugetlbfs: Disabling because there are no supported hugepage sizes\n"); > + return -ENOTSUPP; > + } > + > error = bdi_init(&hugetlbfs_backing_dev_info); > if (error) > return error; KERN_ERR feels like overkill for this type of issue. KERN_INFO?
diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index d19b30a..cc8fcc7 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -1017,6 +1017,11 @@ static int __init init_hugetlbfs_fs(void) int error; int i; + if (!hugepages_supported()) { + printk(KERN_ERR "hugetlbfs: Disabling because there are no supported hugepage sizes\n"); + return -ENOTSUPP; + } + error = bdi_init(&hugetlbfs_backing_dev_info); if (error) return error; diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 8c43cc4..0aea8de 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -450,4 +450,14 @@ static inline spinlock_t *huge_pte_lock(struct hstate *h, return ptl; } +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; +} + #endif /* _LINUX_HUGETLB_H */ diff --git a/mm/hugetlb.c b/mm/hugetlb.c index c01cb9f..1c99585 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -1949,11 +1949,7 @@ module_exit(hugetlb_exit); static int __init hugetlb_init(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 - */ - if (HPAGE_SHIFT == 0) + if (!hugepages_supported()) return 0; if (!size_to_hstate(default_hstate_size)) { @@ -2069,6 +2065,9 @@ static int hugetlb_sysctl_handler_common(bool obey_mempolicy, unsigned long tmp; int ret; + if (!hugepages_supported()) + return -ENOTSUPP; + tmp = h->max_huge_pages; if (write && h->order >= MAX_ORDER) @@ -2122,6 +2121,9 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write, unsigned long tmp; int ret; + if (!hugepages_supported()) + return -ENOTSUPP; + tmp = h->nr_overcommit_huge_pages; if (write && h->order >= MAX_ORDER) @@ -2147,6 +2149,8 @@ out: void hugetlb_report_meminfo(struct seq_file *m) { struct hstate *h = &default_hstate; + if (!hugepages_supported()) + return; seq_printf(m, "HugePages_Total: %5lu\n" "HugePages_Free: %5lu\n" @@ -2163,6 +2167,8 @@ void hugetlb_report_meminfo(struct seq_file *m) int hugetlb_report_node_meminfo(int nid, char *buf) { struct hstate *h = &default_hstate; + if (!hugepages_supported()) + return 0; return sprintf(buf, "Node %d HugePages_Total: %5u\n" "Node %d HugePages_Free: %5u\n" @@ -2177,6 +2183,9 @@ void hugetlb_show_meminfo(void) struct hstate *h; int nid; + if (!hugepages_supported()) + return; + for_each_node_state(nid, N_MEMORY) for_each_hstate(h) pr_info("Node %d hugepages_total=%u hugepages_free=%u hugepages_surp=%u hugepages_size=%lukB\n",
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. Signed-off-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>