Re: [PATCH] fs: use kmalloc() to allocate fdmem if possible

Tetsuo Handa
2010-05-03T00:15:28Z

Avi Kivity wrote:
> On 05/02/2010 07:46 PM, Changli Gao wrote:
> > use kmalloc() to allocate fdmem if possible.
> >
> > vmalloc() is used as a fallback solution for fdmem allocation. Two members are
> > added into the hole of the structure fdtable to indicate if vmalloc() is used
> > or not.
> >
> >
> > diff --git a/fs/file.c b/fs/file.c
> > index 34bb7f7..f71dd85 100644
> > --- a/fs/file.c
> > +++ b/fs/file.c
> > @@ -39,28 +39,34 @@ int sysctl_nr_open_max = 1024 * 1024; /* raised later */
> > */
> > static DEFINE_PER_CPU(struct fdtable_defer, fdtable_defer_list);
> >
> > -static inline void * alloc_fdmem(unsigned int size)
> > +static inline void *alloc_fdmem(unsigned int size, unsigned short *use_vmalloc)
> > {
> > - if (size<= PAGE_SIZE)
> > - return kmalloc(size, GFP_KERNEL);
> > - else
> > - return vmalloc(size);
> > + void *data;
> > +
> > + data = kmalloc(size, GFP_KERNEL);
> > + if (data != NULL) {
> > + *use_vmalloc = 0;
> > + return data;
> > + }
> > + *use_vmalloc = 1;
> > +
> > + return vmalloc(size);
> > }
> >
>
> Perhaps vmalloc() should do this by itself? vfree() can examine the
> pointer and call kfree() if it isn't within the vmalloc address range.

You can use is_vmalloc_addr().

if (is_vmalloc_addr(p))
vfree(p);
else
kfree(p);