From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail190.messagelabs.com (mail190.messagelabs.com [216.82.249.51]) by kanga.kvack.org (Postfix) with SMTP id 4AE236B003D for ; Sat, 2 May 2009 22:09:38 -0400 (EDT) Date: Sat, 2 May 2009 22:08:41 -0400 From: Rik van Riel Subject: Re: [PATCH 1/6] ksm: limiting the num of mem regions user can register per fd. Message-ID: <20090502220841.376eb730@riellaptop.surriel.com> In-Reply-To: <1241302572-4366-2-git-send-email-ieidus@redhat.com> References: <1241302572-4366-1-git-send-email-ieidus@redhat.com> <1241302572-4366-2-git-send-email-ieidus@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: Izik Eidus Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, aarcange@redhat.com, chrisw@redhat.com, alan@lxorguk.ukuu.org.uk, device@lanana.org, linux-mm@kvack.org, hugh@veritas.com, nickpiggin@yahoo.com.au List-ID: On Sun, 3 May 2009 01:16:07 +0300 Izik Eidus wrote: > Right now user can open /dev/ksm fd and register unlimited number of > regions, such behavior may allocate unlimited amount of kernel memory > and get the whole host into out of memory situation. > > Signed-off-by: Izik Eidus > --- > mm/ksm.c | 15 +++++++++++++++ > 1 files changed, 15 insertions(+), 0 deletions(-) > > diff --git a/mm/ksm.c b/mm/ksm.c > index 6165276..d58db6b 100644 > --- a/mm/ksm.c > +++ b/mm/ksm.c > @@ -48,6 +48,9 @@ static int rmap_hash_size; > module_param(rmap_hash_size, int, 0); > MODULE_PARM_DESC(rmap_hash_size, "Hash table size for the reverse > mapping"); > +static int regions_per_fd; > +module_param(regions_per_fd, int, 0); > + > /* > * ksm_mem_slot - hold information for an userspace scanning range > * (the scanning for this region will be from addr untill addr + > @@ -67,6 +70,7 @@ struct ksm_mem_slot { > */ > struct ksm_sma { > struct list_head sma_slots; > + int nregions; > }; > > /** > @@ -453,6 +457,11 @@ static int > ksm_sma_ioctl_register_memory_region(struct ksm_sma *ksm_sma, struct > ksm_mem_slot *slot; int ret = -EPERM; > > + if ((ksm_sma->nregions + 1) > regions_per_fd) { > + ret = -EBUSY; > + goto out; > + } > + > slot = kzalloc(sizeof(struct ksm_mem_slot), GFP_KERNEL); > if (!slot) { > ret = -ENOMEM; > @@ -473,6 +482,7 @@ static int > ksm_sma_ioctl_register_memory_region(struct ksm_sma *ksm_sma, > list_add_tail(&slot->link, &slots); > list_add_tail(&slot->sma_link, &ksm_sma->sma_slots); > + ksm_sma->nregions++; > > up_write(&slots_lock); > return 0; > @@ -511,6 +521,7 @@ static int > ksm_sma_ioctl_remove_memory_region(struct ksm_sma *ksm_sma) > mmput(slot->mm); list_del(&slot->sma_link); > kfree(slot); > + ksm_sma->nregions--; > } > up_write(&slots_lock); > return 0; > @@ -1389,6 +1400,7 @@ static int > ksm_dev_ioctl_create_shared_memory_area(void) } > > INIT_LIST_HEAD(&ksm_sma->sma_slots); > + ksm_sma->nregions = 0; > > fd = anon_inode_getfd("ksm-sma", &ksm_sma_fops, ksm_sma, 0); > if (fd < 0) > @@ -1631,6 +1643,9 @@ static int __init ksm_init(void) > if (r) > goto out_free1; > > + if (!regions_per_fd) > + regions_per_fd = 1024; > + > ksm_thread = kthread_run(ksm_scan_thread, NULL, "kksmd"); > if (IS_ERR(ksm_thread)) { > printk(KERN_ERR "ksm: creating kthread failed\n"); -- All rights reversed. -- 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