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Shutemov" , Mike Kravetz , Minchan Kim , Russell King , Thomas Bogendoerfer , Thomas Gleixner , Vishal Verma , Vlastimil Babka , Will Deacon , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: [PATCH 3/6] mremap: Don't allow MREMAP_DONTUNMAP on special_mappings and aio Date: Tue, 13 Oct 2020 02:34:13 +0100 Message-Id: <20201013013416.390574-4-dima@arista.com> X-Mailer: git-send-email 2.28.0 In-Reply-To: <20201013013416.390574-1-dima@arista.com> References: <20201013013416.390574-1-dima@arista.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: As kernel expect to see only one of such mappings, any further operations on the VMA-copy may be unexpected by the kernel. Maybe it's being on the safe side, but there doesn't seem to be any expected use-case for this, so restrict it now. Fixes: commit e346b3813067 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()"= ) Signed-off-by: Dmitry Safonov --- arch/x86/kernel/cpu/resctrl/pseudo_lock.c | 2 +- fs/aio.c | 5 ++++- include/linux/mm.h | 2 +- mm/mmap.c | 6 +++++- mm/mremap.c | 2 +- 5 files changed, 12 insertions(+), 5 deletions(-) diff --git a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c b/arch/x86/kernel/= cpu/resctrl/pseudo_lock.c index 0daf2f1cf7a8..e916646adc69 100644 --- a/arch/x86/kernel/cpu/resctrl/pseudo_lock.c +++ b/arch/x86/kernel/cpu/resctrl/pseudo_lock.c @@ -1458,7 +1458,7 @@ static int pseudo_lock_dev_release(struct inode *in= ode, struct file *filp) return 0; } =20 -static int pseudo_lock_dev_mremap(struct vm_area_struct *area) +static int pseudo_lock_dev_mremap(struct vm_area_struct *area, unsigned = long flags) { /* Not supported */ return -EINVAL; diff --git a/fs/aio.c b/fs/aio.c index d5ec30385566..3be3c0f77548 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -324,13 +324,16 @@ static void aio_free_ring(struct kioctx *ctx) } } =20 -static int aio_ring_mremap(struct vm_area_struct *vma) +static int aio_ring_mremap(struct vm_area_struct *vma, unsigned long fla= gs) { struct file *file =3D vma->vm_file; struct mm_struct *mm =3D vma->vm_mm; struct kioctx_table *table; int i, res =3D -EINVAL; =20 + if (flags & MREMAP_DONTUNMAP) + return -EINVAL; + spin_lock(&mm->ioctx_lock); rcu_read_lock(); table =3D rcu_dereference(mm->ioctx_table); diff --git a/include/linux/mm.h b/include/linux/mm.h index 16b799a0522c..fd51a4a1f722 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -550,7 +550,7 @@ struct vm_operations_struct { void (*open)(struct vm_area_struct * area); void (*close)(struct vm_area_struct * area); int (*split)(struct vm_area_struct * area, unsigned long addr); - int (*mremap)(struct vm_area_struct * area); + int (*mremap)(struct vm_area_struct *area, unsigned long flags); vm_fault_t (*fault)(struct vm_fault *vmf); vm_fault_t (*huge_fault)(struct vm_fault *vmf, enum page_entry_size pe_size); diff --git a/mm/mmap.c b/mm/mmap.c index bdd19f5b994e..50f853b0ec39 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -3372,10 +3372,14 @@ static const char *special_mapping_name(struct vm= _area_struct *vma) return ((struct vm_special_mapping *)vma->vm_private_data)->name; } =20 -static int special_mapping_mremap(struct vm_area_struct *new_vma) +static int special_mapping_mremap(struct vm_area_struct *new_vma, + unsigned long flags) { struct vm_special_mapping *sm =3D new_vma->vm_private_data; =20 + if (flags & MREMAP_DONTUNMAP) + return -EINVAL; + if (WARN_ON_ONCE(current->mm !=3D new_vma->vm_mm)) return -EFAULT; =20 diff --git a/mm/mremap.c b/mm/mremap.c index c248f9a52125..898e9818ba6d 100644 --- a/mm/mremap.c +++ b/mm/mremap.c @@ -384,7 +384,7 @@ static unsigned long move_vma(struct vm_area_struct *= vma, if (moved_len < old_len) { err =3D -ENOMEM; } else if (vma->vm_ops && vma->vm_ops->mremap) { - err =3D vma->vm_ops->mremap(new_vma); + err =3D vma->vm_ops->mremap(new_vma, flags); } =20 if (unlikely(err)) { --=20 2.28.0