Re: [PATCH v3] shmem: fix a race between shmem_unused_huge_shrink and shmem_evict_inode

On Wed, Nov 24, 2021 at 05:43:16PM +0800, Gang Li wrote:

+move_back:

• /* inodes that are on @list and will not be deleted must be moved back to
  

•  * global list before iput for two reasons:
  

•  * 1. iput in lock: iput call shmem_evict_inode, then cause deadlock.
  

•  * 2. iput before lock: shmem_evict_inode may grab the inode on @list,
  

•  *    which will cause race.
  

•  */
  

• spin_lock(&sbinfo->shrinklist_lock);
  

• list_move(&info->shrinklist, &sbinfo->shrinklist);
  

• sbinfo->shrinklist_len++;
  

• spin_unlock(&sbinfo->shrinklist_lock);
  

+put: iput(inode); }

• spin_lock(&sbinfo->shrinklist_lock);
• list_splice_tail(&list, &sbinfo->shrinklist);
• sbinfo->shrinklist_len -= removed;
• spin_unlock(&sbinfo->shrinklist_lock);
• return split;

}

Okay, I guess it works. Locking is not pretty, but well..

Acked-by: Kirill A. Shutemov kirill.shutemov@linux.intel.com