[PATCH v5 6/7] malloc: Move MORECORE fallback mmap to sysmalloc_mmap_fallback

[DJ Delorie]

LGTM
Reviewed-by: DJ Delorie <dj@redhat.com>

Adhemerval Zanella via Libc-alpha <libc-alpha@sourceware.org> writes:
> diff --git a/malloc/malloc.c b/malloc/malloc.c
> +/*
> +   Allocate memory using mmap() based on S and NB requested size, aligning to
> +   PAGESIZE if required.  The EXTRA_FLAGS is used on mmap() call.  If the call
> +   succeedes S is updated with the allocated size.  This is used as a fallback
> +   if MORECORE fails.
> + */
> +static void *
> +sysmalloc_mmap_fallback (long int *s, INTERNAL_SIZE_T nb,
> +			 INTERNAL_SIZE_T old_size, size_t minsize,
> +			 size_t pagesize, int extra_flags, mstate av)
> +{
> +  long int size = *s;
> +
> +  /* Cannot merge with old top, so add its size back in */
> +  if (contiguous (av))
> +    size = ALIGN_UP (size + old_size, pagesize);
> +
> +  /* If we are relying on mmap as backup, then use larger units */
> +  if ((unsigned long) (size) < minsize)
> +    size = minsize;
> +
> +  /* Don't try if size wraps around 0 */
> +  if ((unsigned long) (size) <= (unsigned long) (nb))
> +    return MORECORE_FAILURE;
> +
> +  char *mbrk = (char *) (MMAP (0, size,
> +			       mtag_mmap_flags | PROT_READ | PROT_WRITE,
> +			       extra_flags));
> +  if (mbrk == MAP_FAILED)
> +    return MAP_FAILED;
> +
> +#ifdef MAP_HUGETLB
> +  if (!(extra_flags & MAP_HUGETLB))
> +    madvise_thp (mbrk, size);
> +#endif
> +
> +  /* Record that we no longer have a contiguous sbrk region.  After the first
> +     time mmap is used as backup, we do not ever rely on contiguous space
> +     since this could incorrectly bridge regions.  */
> +  set_noncontiguous (av);
> +
> +  *s = size;
> +  return mbrk;
> +}
> +
>  static void *
>  sysmalloc (INTERNAL_SIZE_T nb, mstate av)
>  {
> @@ -2695,38 +2740,14 @@ sysmalloc (INTERNAL_SIZE_T nb, mstate av)
>               segregated mmap region.
>             */
>  
> -          /* Cannot merge with old top, so add its size back in */
> -          if (contiguous (av))
> -            size = ALIGN_UP (size + old_size, pagesize);
> -
> -          /* If we are relying on mmap as backup, then use larger units */
> -          if ((unsigned long) (size) < (unsigned long) (MMAP_AS_MORECORE_SIZE))
> -            size = MMAP_AS_MORECORE_SIZE;
> -
> -          /* Don't try if size wraps around 0 */
> -          if ((unsigned long) (size) > (unsigned long) (nb))
> -            {
> -              char *mbrk = (char *) (MMAP (0, size,
> -					   mtag_mmap_flags | PROT_READ | PROT_WRITE,
> -					   0));
> -
> -              if (mbrk != MAP_FAILED)
> -                {
> -		  madvise_thp (mbrk, size);
> -
> -                  /* We do not need, and cannot use, another sbrk call to find end */
> -                  brk = mbrk;
> -                  snd_brk = brk + size;
> -
> -                  /*
> -                     Record that we no longer have a contiguous sbrk region.
> -                     After the first time mmap is used as backup, we do not
> -                     ever rely on contiguous space since this could incorrectly
> -                     bridge regions.
> -                   */
> -                  set_noncontiguous (av);
> -                }
> -            }
> +	  char *mbrk = sysmalloc_mmap_fallback (&size, nb, old_size, pagesize,
> +						MMAP_AS_MORECORE_SIZE, 0, av);
> +	  if (mbrk != MAP_FAILED)
> +	    {
> +	      /* We do not need, and cannot use, another sbrk call to find end */
> +	      brk = mbrk;
> +	      snd_brk = brk + size;
> +	    }
>          }
>  
>        if (brk != (char *) (MORECORE_FAILURE))