From: Dave Kleikamp <dave.kleikamp@oracle.com>
To: David Rientjes <rientjes@google.com>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Kleikamp <shaggy@kernel.org>, Christoph Hellwig <hch@lst.de>,
Sebastian Ott <sebott@linux.vnet.ibm.com>,
Mikulas Patocka <mpatocka@redhat.com>,
Catalin Marinas <catalin.marinas@arm.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
jfs-discussion@lists.sourceforge.net
Subject: Re: [patch 1/4] fs, jfs: remove slab object constructor
Date: Tue, 24 Mar 2015 18:41:29 -0500 [thread overview]
Message-ID: <5511F629.2070907@oracle.com> (raw)
In-Reply-To: <alpine.DEB.2.10.1503241607240.21805@chino.kir.corp.google.com>
On 03/24/2015 06:08 PM, David Rientjes wrote:
> Mempools based on slab caches with object constructors are risky because
> element allocation can happen either from the slab cache itself, meaning
> the constructor is properly called before returning, or from the mempool
> reserve pool, meaning the constructor is not called before returning,
> depending on the allocation context.
>
> For this reason, we should disallow creating mempools based on slab
> caches that have object constructors. Callers of mempool_alloc() will
> be responsible for properly initializing the returned element.
>
> Then, it doesn't matter if the element came from the slab cache or the
> mempool reserved pool.
>
> The only occurrence of a mempool being based on a slab cache with an
> object constructor in the tree is in fs/jfs/jfs_metapage.c. Remove it
> and properly initialize the element in alloc_metapage().
>
> At the same time, META_free is never used, so remove it as well.
>
> Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: Dave Kleikamp <dave.kleikamp@oracle.com>
> ---
> fs/jfs/jfs_metapage.c | 31 ++++++++++++-------------------
> fs/jfs/jfs_metapage.h | 1 -
> 2 files changed, 12 insertions(+), 20 deletions(-)
>
> diff --git a/fs/jfs/jfs_metapage.c b/fs/jfs/jfs_metapage.c
> --- a/fs/jfs/jfs_metapage.c
> +++ b/fs/jfs/jfs_metapage.c
> @@ -183,30 +183,23 @@ static inline void remove_metapage(struct page *page, struct metapage *mp)
>
> #endif
>
> -static void init_once(void *foo)
> -{
> - struct metapage *mp = (struct metapage *)foo;
> -
> - mp->lid = 0;
> - mp->lsn = 0;
> - mp->flag = 0;
> - mp->data = NULL;
> - mp->clsn = 0;
> - mp->log = NULL;
> - set_bit(META_free, &mp->flag);
> - init_waitqueue_head(&mp->wait);
> -}
> -
> static inline struct metapage *alloc_metapage(gfp_t gfp_mask)
> {
> - return mempool_alloc(metapage_mempool, gfp_mask);
> + struct metapage *mp = mempool_alloc(metapage_mempool, gfp_mask);
> +
> + if (mp) {
> + mp->lid = 0;
> + mp->lsn = 0;
> + mp->data = NULL;
> + mp->clsn = 0;
> + mp->log = NULL;
> + init_waitqueue_head(&mp->wait);
> + }
> + return mp;
> }
>
> static inline void free_metapage(struct metapage *mp)
> {
> - mp->flag = 0;
> - set_bit(META_free, &mp->flag);
> -
> mempool_free(mp, metapage_mempool);
> }
>
> @@ -216,7 +209,7 @@ int __init metapage_init(void)
> * Allocate the metapage structures
> */
> metapage_cache = kmem_cache_create("jfs_mp", sizeof(struct metapage),
> - 0, 0, init_once);
> + 0, 0, NULL);
> if (metapage_cache == NULL)
> return -ENOMEM;
>
> diff --git a/fs/jfs/jfs_metapage.h b/fs/jfs/jfs_metapage.h
> --- a/fs/jfs/jfs_metapage.h
> +++ b/fs/jfs/jfs_metapage.h
> @@ -48,7 +48,6 @@ struct metapage {
>
> /* metapage flag */
> #define META_locked 0
> -#define META_free 1
> #define META_dirty 2
> #define META_sync 3
> #define META_discard 4
>
next prev parent reply other threads:[~2015-03-24 23:42 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-24 23:08 [patch 1/4] fs, jfs: remove slab object constructor David Rientjes
2015-03-24 23:09 ` [patch 2/4] mm, mempool: disallow mempools based on slab caches with constructors David Rientjes
2015-03-24 23:09 ` [patch v2 3/4] mm, mempool: poison elements backed by slab allocator David Rientjes
2015-03-24 23:10 ` [patch v2 4/4] mm, mempool: poison elements backed by page allocator David Rientjes
2015-03-25 21:55 ` Andrew Morton
2015-03-26 16:07 ` Andrey Ryabinin
2015-03-26 20:38 ` Andrey Ryabinin
2015-03-26 22:50 ` David Rientjes
2015-03-30 8:53 ` Andrey Ryabinin
2015-03-31 11:33 ` Andrey Ryabinin
2015-04-03 1:04 ` David Rientjes
2015-04-03 1:07 ` [patch -mm] mm, mempool: poison elements backed by page allocator fix fix David Rientjes
2015-03-24 23:41 ` Dave Kleikamp [this message]
2015-03-26 2:18 ` [patch 1/4] fs, jfs: remove slab object constructor Mikulas Patocka
2015-03-26 2:37 ` David Rientjes
2015-03-26 7:28 ` Christoph Hellwig
2015-03-26 14:57 ` Dave Kleikamp
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