Commit 668ed92e authored by Chuck Lever's avatar Chuck Lever
Browse files

NFSD: WARN when freeing an item still linked via nf_lru 



Add a guardrail to prevent freeing memory that is still on a list.
This includes either a dispose list or the LRU list.

This is the sign of a bug, but this class of bugs can be detected
so that they don't endanger system stability, especially while
debugging.

Reviewed-by: default avatarJeff Layton <jlayton@kernel.org>
Signed-off-by: default avatarChuck Lever <chuck.lever@oracle.com>
parent 2e6c6e4c

fs/nfsd/filecache.c

+10 −2
Original line number Diff line number Diff line
@@ -214,6 +214,14 @@ nfsd_file_free(struct nfsd_file *nf) 
		fput(nf->nf_file);

		flush = true;

	}



	/*

	 * If this item is still linked via nf_lru, that's a bug.

	 * WARN and leak it to preserve system stability.

	 */

	if (WARN_ON_ONCE(!list_empty(&nf->nf_lru)))

		return flush;



	call_rcu(&nf->nf_rcu, nfsd_file_slab_free);

	return flush;

}
@@ -343,7 +351,7 @@ nfsd_file_dispose_list(struct list_head *dispose) 


	while(!list_empty(dispose)) {

		nf = list_first_entry(dispose, struct nfsd_file, nf_lru);

		list_del(&nf->nf_lru);

		list_del_init(&nf->nf_lru);

		nfsd_file_flush(nf);

		nfsd_file_put_noref(nf);

	}
@@ -357,7 +365,7 @@ nfsd_file_dispose_list_sync(struct list_head *dispose) 


	while(!list_empty(dispose)) {

		nf = list_first_entry(dispose, struct nfsd_file, nf_lru);

		list_del(&nf->nf_lru);

		list_del_init(&nf->nf_lru);

		nfsd_file_flush(nf);

		if (!refcount_dec_and_test(&nf->nf_ref))

			continue;