Subject: [merged] hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported.patch removed from -mm tree To: nacc@xxxxxxxxxxxxxxxxxx,aneesh.kumar@xxxxxxxxxxxxxxxxxx,mgorman@xxxxxxx,rdunlap@xxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Wed, 07 May 2014 12:05:01 -0700 The patch titled Subject: hugetlb: ensure hugepage access is denied if hugepages are not supported has been removed from the -mm tree. Its filename was hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported.patch This patch was dropped because it was merged into mainline or a subsystem tree ------------------------------------------------------ From: Nishanth Aravamudan <nacc@xxxxxxxxxxxxxxxxxx> Subject: 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@xxxxxxxxxxxxxxxxxxxx: use pr_info(), per Mel] [akpm@xxxxxxxxxxxxxxxxxxxx: fix build when HPAGE_SHIFT is undefined] Signed-off-by: Nishanth Aravamudan <nacc@xxxxxxxxxxxxxxxxxx> Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Acked-by: Mel Gorman <mgorman@xxxxxxx> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- fs/hugetlbfs/inode.c | 5 +++++ include/linux/hugetlb.h | 10 ++++++++++ mm/hugetlb.c | 19 ++++++++++++++----- 3 files changed, 29 insertions(+), 5 deletions(-) diff -puN fs/hugetlbfs/inode.c~hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported fs/hugetlbfs/inode.c --- a/fs/hugetlbfs/inode.c~hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported +++ a/fs/hugetlbfs/inode.c @@ -1030,6 +1030,11 @@ static int __init init_hugetlbfs_fs(void int error; int i; + if (!hugepages_supported()) { + pr_info("hugetlbfs: disabling because there are no supported hugepage sizes\n"); + return -ENOTSUPP; + } + error = bdi_init(&hugetlbfs_backing_dev_info); if (error) return error; diff -puN include/linux/hugetlb.h~hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported include/linux/hugetlb.h --- a/include/linux/hugetlb.h~hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported +++ a/include/linux/hugetlb.h @@ -412,6 +412,16 @@ static inline spinlock_t *huge_pte_lockp 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 diff -puN mm/hugetlb.c~hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported mm/hugetlb.c --- a/mm/hugetlb.c~hugetlb-ensure-hugepage-access-is-denied-if-hugepages-are-not-supported +++ a/mm/hugetlb.c @@ -1981,11 +1981,7 @@ static int __init hugetlb_init(void) { int i; - /* 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)) { @@ -2112,6 +2108,9 @@ static int hugetlb_sysctl_handler_common unsigned long tmp; int ret; + if (!hugepages_supported()) + return -ENOTSUPP; + tmp = h->max_huge_pages; if (write && h->order >= MAX_ORDER) @@ -2165,6 +2164,9 @@ int hugetlb_overcommit_handler(struct ct unsigned long tmp; int ret; + if (!hugepages_supported()) + return -ENOTSUPP; + tmp = h->nr_overcommit_huge_pages; if (write && h->order >= MAX_ORDER) @@ -2190,6 +2192,8 @@ 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" @@ -2206,6 +2210,8 @@ void hugetlb_report_meminfo(struct seq_f 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" @@ -2220,6 +2226,9 @@ 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", _ Patches currently in -mm which might be from nacc@xxxxxxxxxxxxxxxxxx are origin.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html