At Fri, 22 Jun 2007 09:56:35 -0500,
Matt Mackall wrote:
> 
> On Fri, Jun 22, 2007 at 05:08:07PM +0900, Yoshinori Sato wrote:
> > Because the page which SLOB allocator got does not have PG_slab,
> 
> This is for a NOMMU system?

Yes.
 
> You're using an old kernel with an old version of SLOB. SLOB in newer
> kernels actually sets per-page flags. Nick, can you see any reason not
> to s/PG_active/PG_slab/ in the current code?

in mm/nommu.c
   109  unsigned int kobjsize(const void *objp)
   110  {
    :
   116          if (PageSlab(page))
   117                  return ksize(objp);
    :
   122          return (PAGE_SIZE << page->index);
   123  }

PG_slab is verified here.


> > Signed-off-by: Yoshinori Sato <[EMAIL PROTECTED]>
> > 
> > diff --git a/mm/slob.c b/mm/slob.c
> > index 71976c5..d10bcda 100644
> > --- a/mm/slob.c
> > +++ b/mm/slob.c
> > @@ -73,6 +73,21 @@ static DEFINE_SPINLOCK(block_lock);
> >  static void slob_free(void *b, int size);
> >  static void slob_timer_cbk(void);
> >  
> > +static inline void set_slabflags(const void *ptr, int order)
> > +{
> > +   int i;
> > +   struct page *page = virt_to_page(ptr);
> > +   for (i = 0; i < (1 << order); i++)
> > +           __SetPageSlab(page++);
> > +}
> > +
> > +static inline void clear_slabflags(const void *ptr, int order)
> > +{
> > +   int i;
> > +   struct page *page = virt_to_page(ptr);
> > +   for (i = 0; i < (1 << order); i++)
> > +           __ClearPageSlab(page++);
> > +}
> >  
> >  static void *slob_alloc(size_t size, gfp_t gfp, int align)
> >  {
> > @@ -180,6 +195,7 @@ void *__kmalloc(size_t size, gfp_t gfp)
> >     bb->pages = (void *)__get_free_pages(gfp, bb->order);
> >  
> >     if (bb->pages) {
> > +           set_slabflags(bb->pages, bb->order);
> >             spin_lock_irqsave(&block_lock, flags);
> >             bb->next = bigblocks;
> >             bigblocks = bb;
> > @@ -240,6 +256,7 @@ void kfree(const void *block)
> >                     if (bb->pages == block) {
> >                             *last = bb->next;
> >                             spin_unlock_irqrestore(&block_lock, flags);
> > +                           clear_slabflags(block, bb->order);
> >                             free_pages((unsigned long)block, bb->order);
> >                             slob_free(bb, sizeof(bigblock_t));
> >                             return;
> > @@ -323,9 +340,11 @@ void *kmem_cache_alloc(struct kmem_cache *c, gfp_t 
> > flags)
> >  
> >     if (c->size < PAGE_SIZE)
> >             b = slob_alloc(c->size, flags, c->align);
> > -   else
> > +   else {
> >             b = (void *)__get_free_pages(flags, get_order(c->size));
> > -
> > +           if (b)
> > +                   set_slabflags(b, get_order(c->size));
> > +   }
> >     if (c->ctor)
> >             c->ctor(b, c, 0);
> >  
> > @@ -347,8 +366,10 @@ static void __kmem_cache_free(void *b, int size)
> >  {
> >     if (size < PAGE_SIZE)
> >             slob_free(b, size);
> > -   else
> > +   else {
> > +           clear_slabflags(b, get_order(size));
> >             free_pages((unsigned long)b, get_order(size));
> > +   }
> >  }
> >  
> >  static void kmem_rcu_free(struct rcu_head *head)
> 
> -- 
> Mathematics is the supreme nostalgia of our time.
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