From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f169.google.com (mail-pd0-f169.google.com [209.85.192.169]) by kanga.kvack.org (Postfix) with ESMTP id EC4256B006C for ; Thu, 3 Apr 2014 20:43:07 -0400 (EDT) Received: by mail-pd0-f169.google.com with SMTP id fp1so2536537pdb.14 for ; Thu, 03 Apr 2014 17:43:07 -0700 (PDT) Received: from e28smtp07.in.ibm.com (e28smtp07.in.ibm.com. [122.248.162.7]) by mx.google.com with ESMTPS id xk5si2005362pbc.271.2014.04.03.17.43.05 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Thu, 03 Apr 2014 17:43:06 -0700 (PDT) Received: from /spool/local by e28smtp07.in.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Fri, 4 Apr 2014 06:13:03 +0530 Received: from d28relay05.in.ibm.com (d28relay05.in.ibm.com [9.184.220.62]) by d28dlp03.in.ibm.com (Postfix) with ESMTP id 521911258048 for ; Fri, 4 Apr 2014 06:15:30 +0530 (IST) Received: from d28av01.in.ibm.com (d28av01.in.ibm.com [9.184.220.63]) by d28relay05.in.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s340h4nX66453720 for ; Fri, 4 Apr 2014 06:13:05 +0530 Received: from d28av01.in.ibm.com (localhost [127.0.0.1]) by d28av01.in.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s340gw4F015793 for ; Fri, 4 Apr 2014 06:12:59 +0530 From: "Aneesh Kumar K.V" Subject: Re: hugetlb: ensure hugepage access is denied if hugepages are not supported In-Reply-To: <20140403231413.GB17412@linux.vnet.ibm.com> References: <20140403231413.GB17412@linux.vnet.ibm.com> Date: Fri, 04 Apr 2014 06:12:56 +0530 Message-ID: <87d2gxorfz.fsf@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain Sender: owner-linux-mm@kvack.org List-ID: To: Nishanth Aravamudan , linux-mm@kvack.org Cc: linuxppc-dev@lists.ozlabs.org, nyc@holomorphy.com, benh@kernel.crashing.org, paulus@samba.org, anton@samba.org, akpm@linux-foundation.org Nishanth Aravamudan 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 Reviewed-by: Aneesh Kumar K.V > > 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", -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org