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Message-ID: <c5c4e3e2-930d-f4c1-4d30-f17984079e6e@huaweicloud.com>
Date: Sat, 28 Jun 2025 11:17:29 +0800
From: Yu Kuai <yukuai1@...weicloud.com>
To: Wang Jinchao <wangjinchao600@...il.com>, Song Liu <song@...nel.org>
Cc: linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org,
 "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH v3 1/2] md/raid1: change r1conf->r1bio_pool to a pointer
 type

Hi,

在 2025/06/24 9:55, Wang Jinchao 写道:
> 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_kmalloc_pool() to
> avoid referencing a stack-based wait queue.
> 
> Signed-off-by: Wang Jinchao <wangjinchao600@...il.com>
> ---
>   drivers/md/raid1.c | 39 ++++++++++++++++++---------------------
>   drivers/md/raid1.h |  2 +-
>   2 files changed, 19 insertions(+), 22 deletions(-)
> 
> diff --git a/drivers/md/raid1.c b/drivers/md/raid1.c
> index fd4ce2a4136f..8249cbb89fec 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)
> @@ -1305,9 +1305,8 @@ 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);
> -	/* Ensure no bio records IO_BLOCKED */
> -	memset(r1_bio->bios, 0, conf->raid_disks * sizeof(r1_bio->bios[0]));
> +	r1_bio = mempool_alloc(conf->r1bio_pool, GFP_NOIO);
> +	memset(r1_bio, 0, offsetof(struct r1bio, bios[conf->raid_disks * 2]));
>   	init_r1bio(r1_bio, mddev, bio);
>   	return r1_bio;
>   }
> @@ -3084,6 +3083,7 @@ static struct r1conf *setup_conf(struct mddev *mddev)
>   	int i;
>   	struct raid1_info *disk;
>   	struct md_rdev *rdev;
> +	size_t r1bio_size;
>   	int err = -ENOMEM;
>   
>   	conf = kzalloc(sizeof(struct r1conf), GFP_KERNEL);
> @@ -3124,9 +3124,10 @@ 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)
> +
> +	r1bio_size = offsetof(struct r1bio, bios[mddev->raid_disks * 2]);

The local variable doesn't look necessary, it's just used once anyway.
> +	conf->r1bio_pool = mempool_create_kmalloc_pool(NR_RAID_BIOS, r1bio_size);
> +	if (!conf->r1bio_pool)
>   		goto abort;
>   
>   	err = bioset_init(&conf->bio_split, BIO_POOL_SIZE, 0, 0);
> @@ -3197,7 +3198,7 @@ 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 +3311,7 @@ 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 +3367,14 @@ 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;
> +	size_t new_r1bio_size;
>   	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 +3406,18 @@ 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,
> -			   rbio_pool_free, newpoolinfo);
> -	if (ret) {
> +	new_r1bio_size = offsetof(struct r1bio, bios[raid_disks * 2]);
same here. Otherwise looks good to me.

Reviewed-by: Yu Kuai <yukuai3@...wei.com>
> +	newpool = mempool_create_kmalloc_pool(NR_RAID_BIOS, new_r1bio_size);
> +	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 +3426,6 @@ 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 +3457,7 @@ 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;
> 


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