Re: [PATCH V2 2/5] xfs: Remove kmem_zone_alloc() wrapper

From: "Darrick J. Wong" <darrick.wong@oracle.com>
To: Carlos Maiolino <cmaiolino@redhat.com>
Cc: linux-xfs@vger.kernel.org
Subject: Re: [PATCH V2 2/5] xfs: Remove kmem_zone_alloc() wrapper
Date: Wed, 20 Nov 2019 10:58:35 -0800	[thread overview]
Message-ID: <20191120185835.GO6219@magnolia> (raw)
In-Reply-To: <20191120104425.407213-3-cmaiolino@redhat.com>

On Wed, Nov 20, 2019 at 11:44:22AM +0100, Carlos Maiolino wrote:
> __GFP_NOFAIL can be used for an infinite retry + congestion_wait, so we
> can use kmem_cache_alloc() directly.
> 
> Signed-off-by: Carlos Maiolino <cmaiolino@redhat.com>

Looks ok,
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>

--D

> ---
> V2:
> 	- Rephrase commit log to explain why it's ok to remove the retry
> 	  loop from kmem_zone_alloc().
> 
>  fs/xfs/kmem.c             | 21 ---------------------
>  fs/xfs/kmem.h             |  2 --
>  fs/xfs/libxfs/xfs_alloc.c |  3 ++-
>  fs/xfs/libxfs/xfs_bmap.c  |  3 ++-
>  fs/xfs/xfs_icache.c       |  2 +-
>  fs/xfs/xfs_trace.h        |  1 -
>  6 files changed, 5 insertions(+), 27 deletions(-)
> 
> diff --git a/fs/xfs/kmem.c b/fs/xfs/kmem.c
> index 1da94237a8cf..2644fdaa0549 100644
> --- a/fs/xfs/kmem.c
> +++ b/fs/xfs/kmem.c
> @@ -115,24 +115,3 @@ kmem_realloc(const void *old, size_t newsize, xfs_km_flags_t flags)
>  		congestion_wait(BLK_RW_ASYNC, HZ/50);
>  	} while (1);
>  }
> -
> -void *
> -kmem_zone_alloc(kmem_zone_t *zone, xfs_km_flags_t flags)
> -{
> -	int	retries = 0;
> -	gfp_t	lflags = kmem_flags_convert(flags);
> -	void	*ptr;
> -
> -	trace_kmem_zone_alloc(kmem_cache_size(zone), flags, _RET_IP_);
> -	do {
> -		ptr = kmem_cache_alloc(zone, lflags);
> -		if (ptr || (flags & KM_MAYFAIL))
> -			return ptr;
> -		if (!(++retries % 100))
> -			xfs_err(NULL,
> -		"%s(%u) possible memory allocation deadlock in %s (mode:0x%x)",
> -				current->comm, current->pid,
> -				__func__, lflags);
> -		congestion_wait(BLK_RW_ASYNC, HZ/50);
> -	} while (1);
> -}
> diff --git a/fs/xfs/kmem.h b/fs/xfs/kmem.h
> index 3242de676808..7e4ad73771ce 100644
> --- a/fs/xfs/kmem.h
> +++ b/fs/xfs/kmem.h
> @@ -76,8 +76,6 @@ kmem_zalloc_large(size_t size, xfs_km_flags_t flags)
>  #define kmem_zone	kmem_cache
>  #define kmem_zone_t	struct kmem_cache
>  
> -extern void *kmem_zone_alloc(kmem_zone_t *, xfs_km_flags_t);
> -
>  static inline struct page *
>  kmem_to_page(void *addr)
>  {
> diff --git a/fs/xfs/libxfs/xfs_alloc.c b/fs/xfs/libxfs/xfs_alloc.c
> index 675613c7bacb..42cae87bdd2d 100644
> --- a/fs/xfs/libxfs/xfs_alloc.c
> +++ b/fs/xfs/libxfs/xfs_alloc.c
> @@ -2351,7 +2351,8 @@ xfs_defer_agfl_block(
>  	ASSERT(xfs_bmap_free_item_zone != NULL);
>  	ASSERT(oinfo != NULL);
>  
> -	new = kmem_zone_alloc(xfs_bmap_free_item_zone, 0);
> +	new = kmem_cache_alloc(xfs_bmap_free_item_zone,
> +			       GFP_KERNEL | __GFP_NOFAIL);
>  	new->xefi_startblock = XFS_AGB_TO_FSB(mp, agno, agbno);
>  	new->xefi_blockcount = 1;
>  	new->xefi_oinfo = *oinfo;
> diff --git a/fs/xfs/libxfs/xfs_bmap.c b/fs/xfs/libxfs/xfs_bmap.c
> index 9fbdca183465..37596e49b92e 100644
> --- a/fs/xfs/libxfs/xfs_bmap.c
> +++ b/fs/xfs/libxfs/xfs_bmap.c
> @@ -554,7 +554,8 @@ __xfs_bmap_add_free(
>  #endif
>  	ASSERT(xfs_bmap_free_item_zone != NULL);
>  
> -	new = kmem_zone_alloc(xfs_bmap_free_item_zone, 0);
> +	new = kmem_cache_alloc(xfs_bmap_free_item_zone,
> +			       GFP_KERNEL | __GFP_NOFAIL);
>  	new->xefi_startblock = bno;
>  	new->xefi_blockcount = (xfs_extlen_t)len;
>  	if (oinfo)
> diff --git a/fs/xfs/xfs_icache.c b/fs/xfs/xfs_icache.c
> index 950e8a51ec66..985f48e3795f 100644
> --- a/fs/xfs/xfs_icache.c
> +++ b/fs/xfs/xfs_icache.c
> @@ -40,7 +40,7 @@ xfs_inode_alloc(
>  	 * KM_MAYFAIL and return NULL here on ENOMEM. Set the
>  	 * code up to do this anyway.
>  	 */
> -	ip = kmem_zone_alloc(xfs_inode_zone, 0);
> +	ip = kmem_cache_alloc(xfs_inode_zone, GFP_KERNEL | __GFP_NOFAIL);
>  	if (!ip)
>  		return NULL;
>  	if (inode_init_always(mp->m_super, VFS_I(ip))) {
> diff --git a/fs/xfs/xfs_trace.h b/fs/xfs/xfs_trace.h
> index c13bb3655e48..192f499ccd7e 100644
> --- a/fs/xfs/xfs_trace.h
> +++ b/fs/xfs/xfs_trace.h
> @@ -3571,7 +3571,6 @@ DEFINE_KMEM_EVENT(kmem_alloc);
>  DEFINE_KMEM_EVENT(kmem_alloc_io);
>  DEFINE_KMEM_EVENT(kmem_alloc_large);
>  DEFINE_KMEM_EVENT(kmem_realloc);
> -DEFINE_KMEM_EVENT(kmem_zone_alloc);
>  
>  #endif /* _TRACE_XFS_H */
>  
> -- 
> 2.23.0
> 