linux-kernel - Re: [PATCH] md/raid1: change r1conf->r1bio

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Message-ID: <ldpoy2fo.fsf@damenly.org>
Date: Thu, 19 Jun 2025 08:56:11 +0800
From: Su Yue <l@...enly.org>
To: Wang Jinchao <wangjinchao600@...il.com>
Cc: Song Liu <song@...nel.org>,  Yu Kuai <yukuai3@...wei.com>,
  linux-raid@...r.kernel.org,  linux-kernel@...r.kernel.org
Subject: Re: [PATCH] md/raid1: change r1conf->r1bio_pool to a pointer type

On Wed 18 Jun 2025 at 19:41, Wang Jinchao 
<wangjinchao600@...il.com> wrote:

> In raid1_reshape(), newpool is a stack variable.
> mempool_init() initializes newpool->wait with the stack address.
> After assigning newpool to conf->r1bio_pool, the wait queue
> need to be reinitialized, which is not ideal.
>
> Change raid1_conf->r1bio_pool to a pointer type and
> replace mempool_init() with mempool_create() to
> avoid referencing a stack-based wait queue.
>
> Signed-off-by: Wang Jinchao <wangjinchao600@...il.com>
> ---
>  drivers/md/raid1.c | 31 +++++++++++++------------------
>  drivers/md/raid1.h |  2 +-
>  2 files changed, 14 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index fd4ce2a4136f..4d4833915b5f 100644
> --- a/drivers/md/raid1.c
> +++ b/drivers/md/raid1.c
> @@ -255,7 +255,7 @@ static void free_r1bio(struct r1bio *r1_bio)
>  	struct r1conf *conf = r1_bio->mddev->private;
>
>  	put_all_bios(conf, r1_bio);
> -	mempool_free(r1_bio, &conf->r1bio_pool);
> +	mempool_free(r1_bio, conf->r1bio_pool);
>  }
>
>  static void put_buf(struct r1bio *r1_bio)
> @@ -1305,7 +1305,7 @@ alloc_r1bio(struct mddev *mddev, struct 
> bio *bio)
>  	struct r1conf *conf = mddev->private;
>  	struct r1bio *r1_bio;
>
> -	r1_bio = mempool_alloc(&conf->r1bio_pool, GFP_NOIO);
> +	r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
>  	/* Ensure no bio records IO_BLOCKED */
>  	memset(r1_bio->bios, 0, conf->raid_disks * 
>  sizeof(r1_bio->bios[0]));
>  	init_r1bio(r1_bio, mddev, bio);
> @@ -3124,9 +3124,9 @@ static struct r1conf *setup_conf(struct 
> mddev *mddev)
>  	if (!conf->poolinfo)
>  		goto abort;
>  	conf->poolinfo->raid_disks = mddev->raid_disks * 2;
> -	err = mempool_init(&conf->r1bio_pool, NR_RAID_BIOS, 
> r1bio_pool_alloc,
> -			   rbio_pool_free, conf->poolinfo);
> -	if (err)
> +	conf->r1bio_pool = mempool_create(NR_RAID_BIOS, 
> r1bio_pool_alloc,
> +					  rbio_pool_free, conf->poolinfo);
> +	if (!conf->r1bio_pool)
>
err should be set to -ENOMEM.

--
Su

>  		goto abort;
>
>  	err = bioset_init(&conf->bio_split, BIO_POOL_SIZE, 0, 0);
> @@ -3197,7 +3197,7 @@ static struct r1conf *setup_conf(struct 
> mddev *mddev)
>
>   abort:
>  	if (conf) {
> -		mempool_exit(&conf->r1bio_pool);
> +		mempool_destroy(conf->r1bio_pool);
>  		kfree(conf->mirrors);
>  		safe_put_page(conf->tmppage);
>  		kfree(conf->poolinfo);
> @@ -3310,7 +3310,7 @@ static void raid1_free(struct mddev 
> *mddev, void *priv)
>  {
>  	struct r1conf *conf = priv;
>
> -	mempool_exit(&conf->r1bio_pool);
> +	mempool_destroy(conf->r1bio_pool);
>  	kfree(conf->mirrors);
>  	safe_put_page(conf->tmppage);
>  	kfree(conf->poolinfo);
> @@ -3366,17 +3366,13 @@ static int raid1_reshape(struct mddev 
> *mddev)
>  	 * At the same time, we "pack" the devices so that all the 
>  missing
>  	 * devices have the higher raid_disk numbers.
>  	 */
> -	mempool_t newpool, oldpool;
> +	mempool_t *newpool, *oldpool;
>  	struct pool_info *newpoolinfo;
>  	struct raid1_info *newmirrors;
>  	struct r1conf *conf = mddev->private;
>  	int cnt, raid_disks;
>  	unsigned long flags;
>  	int d, d2;
> -	int ret;
> -
> -	memset(&newpool, 0, sizeof(newpool));
> -	memset(&oldpool, 0, sizeof(oldpool));
>
>  	/* Cannot change chunk_size, layout, or level */
>  	if (mddev->chunk_sectors != mddev->new_chunk_sectors ||
> @@ -3408,18 +3404,18 @@ static int raid1_reshape(struct mddev 
> *mddev)
>  	newpoolinfo->mddev = mddev;
>  	newpoolinfo->raid_disks = raid_disks * 2;
>
> -	ret = mempool_init(&newpool, NR_RAID_BIOS, r1bio_pool_alloc,
> +	newpool = mempool_create(NR_RAID_BIOS, r1bio_pool_alloc,
>  			   rbio_pool_free, newpoolinfo);
> -	if (ret) {
> +	if (!newpool) {
>  		kfree(newpoolinfo);
> -		return ret;
> +		return -ENOMEM;
>  	}
>  	newmirrors = kzalloc(array3_size(sizeof(struct raid1_info),
>  					 raid_disks, 2),
>  			     GFP_KERNEL);
>  	if (!newmirrors) {
>  		kfree(newpoolinfo);
> -		mempool_exit(&newpool);
> +		mempool_destroy(newpool);
>  		return -ENOMEM;
>  	}
>
> @@ -3428,7 +3424,6 @@ static int raid1_reshape(struct mddev 
> *mddev)
>  	/* ok, everything is stopped */
>  	oldpool = conf->r1bio_pool;
>  	conf->r1bio_pool = newpool;
> -	init_waitqueue_head(&conf->r1bio_pool.wait);
>
>  	for (d = d2 = 0; d < conf->raid_disks; d++) {
>  		struct md_rdev *rdev = conf->mirrors[d].rdev;
> @@ -3460,7 +3455,7 @@ static int raid1_reshape(struct mddev 
> *mddev)
>  	set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
>  	md_wakeup_thread(mddev->thread);
>
> -	mempool_exit(&oldpool);
> +	mempool_destroy(oldpool);
>  	return 0;
>  }
>
> diff --git a/drivers/md/raid1.h b/drivers/md/raid1.h
> index 33f318fcc268..652c347b1a70 100644
> --- a/drivers/md/raid1.h
> +++ b/drivers/md/raid1.h
> @@ -118,7 +118,7 @@ struct r1conf {
>  	 * mempools - it changes when the array grows or shrinks
>  	 */
>  	struct pool_info	*poolinfo;
> -	mempool_t		r1bio_pool;
> +	mempool_t		*r1bio_pool;
>  	mempool_t		r1buf_pool;
>
>  	struct bio_set		bio_split;