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Re: [Cluster-devel] GFS2: Use kmalloc when possible for ->readdir()



On Wed, Jul 28, 2010 at 4:15 AM, Steven Whitehouse <swhiteho redhat com> wrote:
>
> We may be able to eliminate vmalloc entirely at some stage,
> but this is easy to do right away.

Quite frankly, I'd much rather see this abstracted out a bit. Why not just do a

  void *memalloc(unsigned int size)
  {
      if (size < KMALLOC_MAX_SIZE) {
         void *ptr = kmalloc(size, GFP_KERNEL | __GFP_NOWARN);
         if (ptr)
            return ptr;
      }
      return vmalloc(size);
   }

   void memfree(void *ptr)
   {
      unsigned long addr = (unsigned long) ptr;

      if (is_vmalloc_addr(addr)) {
         vfree(ptr);
         return;
      }

      kfree(ptr);
   }

wouldn't that be much nicer? No need for that explicit flag, and you
don't mess up an already way-too-ugly function even more.

Also, I do notice that you used GFP_NOFS, but you didn't use that for
the vmalloc() thing. If there really are lock reentrancy reasons, you
_could_ use __vmalloc(size, GFP_NOFS, PAGE_KERNEL).  But since you've
been using vmalloc() for a long time, I suspect GFP_KERNEL works fine.
Yes/no?

                      Linus


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