Jan Kara: > Lockdep complains about a chain: > sb_internal#2 --> &ei->xattr_sem#2 --> fs_reclaim > > and shrink_dentry_list -> ext2_evict_inode -> ext2_xattr_delete_inode -> > down_write(ei->xattr_sem) creating a locking cycle in the reclaim path. > This is however a false positive because when we are in > ext2_evict_inode() we are the only holder of the inode reference and > nobody else should touch xattr_sem of that inode. So we cannot ever > block on acquiring the xattr_sem in the reclaim path. > > Silence the lockdep warning by using down_write_trylock() in > ext2_xattr_delete_inode() to not create false locking dependency. v5.6 is released. But I cannot see this patch applied. Sad. Anyway I am wondering whether acquiring xattr_sem in ext2_xattr_delete_inode() is really necessary or not. It is necessary because this function refers and clears i_file_acl, right? But this function handles the removed (nlink==0) and unused inodes only. If nobody else touches xattr_sem as you wrote, then it is same to i_file_acl, isn't it? Can we replace xattr_sem (only here) by memory barrier, or remove xattr_sem from ext2_xattr_delete_inode()? J. R. Okajima
