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Mon, 20 May 2019 17:00:34 +0300 Subject: [PATCH v2 6/7] mm: Introduce find_vma_filter_flags() helper From: Kirill Tkhai To: akpm@linux-foundation.org, dan.j.williams@intel.com, ktkhai@virtuozzo.com, mhocko@suse.com, keith.busch@intel.com, kirill.shutemov@linux.intel.com, alexander.h.duyck@linux.intel.com, ira.weiny@intel.com, andreyknvl@google.com, arunks@codeaurora.org, vbabka@suse.cz, cl@linux.com, riel@surriel.com, keescook@chromium.org, hannes@cmpxchg.org, npiggin@gmail.com, mathieu.desnoyers@efficios.com, shakeelb@google.com, guro@fb.com, aarcange@redhat.com, hughd@google.com, jglisse@redhat.com, mgorman@techsingularity.net, daniel.m.jordan@oracle.com, jannh@google.com, kilobyte@angband.pl, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Date: Mon, 20 May 2019 17:00:34 +0300 Message-ID: <155836083406.2441.7999607190635457587.stgit@localhost.localdomain> In-Reply-To: <155836064844.2441.10911127801797083064.stgit@localhost.localdomain> References: <155836064844.2441.10911127801797083064.stgit@localhost.localdomain> User-Agent: StGit/0.18 MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patch introduce a new helper, which returns vma of enough length at given address, but only if it does not contain passed flags. v2: New Signed-off-by: Kirill Tkhai --- include/linux/mm.h | 3 +++ mm/mremap.c | 39 ++++++++++++++++++++++++++------------- 2 files changed, 29 insertions(+), 13 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 54328d08dbdd..65ceb56acd44 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1515,6 +1515,9 @@ void unmap_mapping_pages(struct address_space *mapping, pgoff_t start, pgoff_t nr, bool even_cows); void unmap_mapping_range(struct address_space *mapping, loff_t const holebegin, loff_t const holelen, int even_cows); +struct vm_area_struct *find_vma_without_flags(struct mm_struct *mm, + unsigned long addr, unsigned long len, + unsigned long prohibited_flags); #else static inline vm_fault_t handle_mm_fault(struct vm_area_struct *vma, unsigned long address, unsigned int flags) diff --git a/mm/mremap.c b/mm/mremap.c index 9a96cfc28675..dabae6a70287 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -430,14 +430,37 @@ static unsigned long move_vma(struct vm_area_struct *vma, return new_addr; } +struct vm_area_struct *find_vma_without_flags(struct mm_struct *mm, + unsigned long addr, unsigned long len, + unsigned long prohibited_flags) +{ + struct vm_area_struct *vma = find_vma(mm, addr); + + if (!vma || vma->vm_start > addr) + return ERR_PTR(-EFAULT); + + /* vm area boundaries crossing */ + if (len > vma->vm_end - addr) + return ERR_PTR(-EFAULT); + + if (vma->vm_flags & prohibited_flags) + return ERR_PTR(-EFAULT); + + return vma; +} + static struct vm_area_struct *vma_to_resize(unsigned long addr, unsigned long old_len, unsigned long new_len, unsigned long *p) { struct mm_struct *mm = current->mm; - struct vm_area_struct *vma = find_vma(mm, addr); - unsigned long pgoff; + struct vm_area_struct *vma; + unsigned long pgoff, prohibited_flags = VM_HUGETLB; - if (!vma || vma->vm_start > addr) + if (old_len != new_len) + prohibited_flags |= VM_DONTEXPAND | VM_PFNMAP; + + vma = find_vma_without_flags(mm, addr, old_len, prohibited_flags); + if (IS_ERR(vma)) return ERR_PTR(-EFAULT); /* @@ -453,13 +476,6 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, return ERR_PTR(-EINVAL); } - if (is_vm_hugetlb_page(vma)) - return ERR_PTR(-EINVAL); - - /* We can't remap across vm area boundaries */ - if (old_len > vma->vm_end - addr) - return ERR_PTR(-EFAULT); - if (new_len == old_len) return vma; @@ -469,9 +485,6 @@ static struct vm_area_struct *vma_to_resize(unsigned long addr, if (pgoff + (new_len >> PAGE_SHIFT) < pgoff) return ERR_PTR(-EINVAL); - if (vma->vm_flags & (VM_DONTEXPAND | VM_PFNMAP)) - return ERR_PTR(-EFAULT); - if (vma->vm_flags & VM_LOCKED) { unsigned long locked, lock_limit; locked = atomic64_read(&mm->locked_vm) << PAGE_SHIFT;