Re: [patch] slqb: remove unnecessary conditional in kmem_cache_create

[Pekka Enberg <penberg@cs.helsinki.fi>]

David Rientjes wrote:
> kmem_cache_open() panics when a SLAB_PANIC cache cannot be opened because
> it has early callers using the flag that do not go through
> kmem_cache_create().
> 
> If kmem_cache_open() fails for a SLAB_PANIC cache, it would have panicked
> the machine.  Thus, checking for this flag in kmem_cache_create() is
> unnecessary in the error patch since it is always clear.

Yes, but there are other error cases in kmem_cache_create() that "goto 
err" for which we do need to check for SLAB_PANIC.

> 
> Cc: Nick Piggin <npiggin@suse.de>
> Signed-off-by: David Rientjes <rientjes@google.com>
> ---
>  mm/slqb.c |    3 ---
>  1 files changed, 0 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/slqb.c b/mm/slqb.c
> --- a/mm/slqb.c
> +++ b/mm/slqb.c
> @@ -3077,9 +3077,6 @@ struct kmem_cache *kmem_cache_create(const char *name, size_t size,
>  
>  err:
>  	up_write(&slqb_lock);
> -	if (flags & SLAB_PANIC)
> -		panic("%s: failed to create slab `%s'\n", __func__, name);
> -
>  	return NULL;
>  }
>  EXPORT_SYMBOL(kmem_cache_create);