Re: [PATCH] md/raid1: change r1conf->r1bio_pool to a pointer type

[Wang Jinchao <wangjinchao600@gmail.com>]

On 6/19/25 08:56, Su Yue wrote:
> On Wed 18 Jun 2025 at 19:41, Wang Jinchao <wangjinchao600@gmail.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@gmail.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.
> 
At the beginning of the function, err is initialized 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;