Re: [RFC PATCH v3 09/10] mm: create __do_mmap() to take an mm_struct * arg

[Anthony Yznaga]

On 10/7/24 1:44 AM, Kirill A. Shutemov wrote:
> On Tue, Sep 03, 2024 at 04:22:40PM -0700, Anthony Yznaga wrote:
> > In preparation for mapping objects into an mshare region, create
> > __do_mmap() to allow mapping into a specified mm. There are no
> > functional changes otherwise.
> >
> > Signed-off-by: Anthony Yznaga <anthony.yznaga@xxxxxxxxxx>
> > ---
> >   include/linux/mm.h | 18 +++++++++++++++++-
> >   mm/mmap.c          | 12 +++++-------
> >   2 files changed, 22 insertions(+), 8 deletions(-)
> >
> > diff --git a/include/linux/mm.h b/include/linux/mm.h
> > index 3aa0b3322284..a9afbda73cb0 100644
> > --- a/include/linux/mm.h
> > +++ b/include/linux/mm.h
> > @@ -3409,11 +3409,27 @@ get_unmapped_area(struct file *file, unsigned long addr, unsigned long len,
> >   
> >   extern unsigned long mmap_region(struct file *file, unsigned long addr,
> >   	unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
> > -	struct list_head *uf);
> > +	struct list_head *uf, struct mm_struct *mm);
> > +#ifdef CONFIG_MMU
> > +extern unsigned long __do_mmap(struct file *file, unsigned long addr,
> > +	unsigned long len, unsigned long prot, unsigned long flags,
> > +	vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
> > +	struct list_head *uf, struct mm_struct *mm);
> > +static inline unsigned long do_mmap(struct file *file, unsigned long addr,
> > +	unsigned long len, unsigned long prot, unsigned long flags,
> > +	vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
> > +	struct list_head *uf)
> > +{
> > +	return __do_mmap(file, addr, len, prot, flags, vm_flags, pgoff,
> > +			 populate, uf, current->mm);
> > +}
> > +#else
> >   extern unsigned long do_mmap(struct file *file, unsigned long addr,
> >   	unsigned long len, unsigned long prot, unsigned long flags,
> >   	vm_flags_t vm_flags, unsigned long pgoff, unsigned long *populate,
> >   	struct list_head *uf);
> > +#endif
> > +
> >   extern int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
> >   			 unsigned long start, size_t len, struct list_head *uf,
> >   			 bool unlock);
> > diff --git a/mm/mmap.c b/mm/mmap.c
> > index d0dfc85b209b..4112f18e7302 100644
> > --- a/mm/mmap.c
> > +++ b/mm/mmap.c
> > @@ -1250,15 +1250,14 @@ static inline bool file_mmap_ok(struct file *file, struct inode *inode,
> >   }
> >   
> >   /*
> > - * The caller must write-lock current->mm->mmap_lock.
> > + * The caller must write-lock mm->mmap_lock.
> >    */
> > -unsigned long do_mmap(struct file *file, unsigned long addr,
> > +unsigned long __do_mmap(struct file *file, unsigned long addr,
> >   			unsigned long len, unsigned long prot,
> >   			unsigned long flags, vm_flags_t vm_flags,
> >   			unsigned long pgoff, unsigned long *populate,
> > -			struct list_head *uf)
> > +			struct list_head *uf, struct mm_struct *mm)
> Argument list getting too long. At some point we need to have a struct to
> pass them around.

I'll look into doing that.


Anthony

> >   {
> > -	struct mm_struct *mm = current->mm;
> >   	int pkey = 0;
> >   
> >   	*populate = 0;
> > @@ -1465,7 +1464,7 @@ unsigned long do_mmap(struct file *file, unsigned long addr,
> >   			vm_flags |= VM_NORESERVE;
> >   	}
> >   
> > -	addr = mmap_region(file, addr, len, vm_flags, pgoff, uf);
> > +	addr = mmap_region(file, addr, len, vm_flags, pgoff, uf, mm);
> >   	if (!IS_ERR_VALUE(addr) &&
> >   	    ((vm_flags & VM_LOCKED) ||
> >   	     (flags & (MAP_POPULATE | MAP_NONBLOCK)) == MAP_POPULATE))
> > @@ -2848,9 +2847,8 @@ int do_munmap(struct mm_struct *mm, unsigned long start, size_t len,
> >   
> >   unsigned long mmap_region(struct file *file, unsigned long addr,
> >   		unsigned long len, vm_flags_t vm_flags, unsigned long pgoff,
> > -		struct list_head *uf)
> > +		struct list_head *uf, struct mm_struct *mm)
> >   {
> > -	struct mm_struct *mm = current->mm;
> >   	struct vm_area_struct *vma = NULL;
> >   	struct vm_area_struct *next, *prev, *merge;
> >   	pgoff_t pglen = len >> PAGE_SHIFT;
> > --
> > 2.43.5