From: Vlastimil Babka <vbabka@suse.cz>
To: Mike Kravetz <mike.kravetz@oracle.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Cc: Andrew Morton <akpm@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Michal Hocko <mhocko@suse.com>, Aaron Lu <aaron.lu@intel.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Anshuman Khandual <khandual@linux.vnet.ibm.com>,
Linux API <linux-api@vger.kernel.org>
Subject: Re: [PATCH] mm/mremap: Fail map duplication attempts for private mappings
Date: Thu, 13 Jul 2017 21:11:08 +0200 [thread overview]
Message-ID: <4e921eb5-8741-3337-9a7d-5ec9473412da@suse.cz> (raw)
In-Reply-To: <1499961495-8063-1-git-send-email-mike.kravetz@oracle.com>
[+CC linux-api]
On 07/13/2017 05:58 PM, Mike Kravetz wrote:
> mremap will create a 'duplicate' mapping if old_size == 0 is
> specified. Such duplicate mappings make no sense for private
> mappings. If duplication is attempted for a private mapping,
> mremap creates a separate private mapping unrelated to the
> original mapping and makes no modifications to the original.
> This is contrary to the purpose of mremap which should return
> a mapping which is in some way related to the original.
>
> Therefore, return EINVAL in the case where if an attempt is
> made to duplicate a private mapping.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> mm/mremap.c | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> diff --git a/mm/mremap.c b/mm/mremap.c
> index cd8a1b1..076f506 100644
> --- a/mm/mremap.c
> +++ b/mm/mremap.c
> @@ -383,6 +383,13 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr,
> if (!vma || vma->vm_start > addr)
> return ERR_PTR(-EFAULT);
>
> + /*
> + * !old_len is a special case where a mapping is 'duplicated'.
> + * Do not allow this for private mappings.
> + */
> + if (!old_len && !(vma->vm_flags & (VM_SHARED | VM_MAYSHARE)))
> + return ERR_PTR(-EINVAL);
> +
> if (is_vm_hugetlb_page(vma))
> return ERR_PTR(-EINVAL);
>
>
--
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next prev parent reply other threads:[~2017-07-13 19:11 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-13 15:58 [PATCH] mm/mremap: Fail map duplication attempts for private mappings Mike Kravetz
2017-07-13 19:11 ` Vlastimil Babka [this message]
2017-07-13 22:33 ` Mike Kravetz
2017-07-14 4:51 ` Anshuman Khandual
2017-07-14 8:26 ` Michal Hocko
2017-07-14 17:29 ` Mike Kravetz
2017-07-17 6:44 ` Michal Hocko
2017-07-19 16:39 ` Mike Kravetz
2017-07-20 8:20 ` Michal Hocko
2017-07-20 20:37 ` [PATCH v2] " Mike Kravetz
2017-07-21 14:36 ` Michal Hocko
2017-07-21 21:18 ` Mike Kravetz
2017-07-24 8:50 ` Michal Hocko
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