[colyli-bcache:for-next 4/7] drivers/md/bcache/btree.c:1511 btree_gc_rewrite_node() error: 'n' dereferencing possible ERR_PTR()

[kernel test robot <lkp@intel.com>]

BCC: lkp@intel.com
CC: oe-kbuild-all@lists.linux.dev
TO: Zheng Wang <zyytlz.wz@163.com>
CC: Coly Li <colyli@suse.de>

Hi Zheng,

FYI, the error/warning was bisected to this commit, please ignore it if it's irrelevant.

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/colyli/linux-bcache.git for-next
head:   313c29cf50657b993b76a2df466b9c09ac8f3d83
commit: 71e765f4f8e55289201daa575331e011f80c0b12 [4/7] bcache: Remove some unnecessary NULL point check for the return value of __bch_btree_node_alloc-related pointer
:::::: branch date: 5 days ago
:::::: commit date: 11 days ago
config: parisc-randconfig-m031-20230608 (https://download.01.org/0day-ci/archive/20230611/202306110753.VR6S20cb-lkp@intel.com/config)
compiler: hppa-linux-gcc (GCC) 12.3.0

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Reported-by: Dan Carpenter <error27@gmail.com>
| Closes: https://lore.kernel.org/r/202306110753.VR6S20cb-lkp@intel.com/

New smatch warnings:
drivers/md/bcache/btree.c:1511 btree_gc_rewrite_node() error: 'n' dereferencing possible ERR_PTR()

Old smatch warnings:
arch/parisc/include/asm/hash.h:44 __hash_32() warn: inconsistent indenting
drivers/md/bcache/btree.c:1527 btree_gc_rewrite_node() error: 'n' dereferencing possible ERR_PTR()

vim +/n +1511 drivers/md/bcache/btree.c

cafe563591446c Kent Overstreet 2013-03-23  1496  
0a63b66db566cf Kent Overstreet 2014-03-17  1497  static int btree_gc_rewrite_node(struct btree *b, struct btree_op *op,
0a63b66db566cf Kent Overstreet 2014-03-17  1498  				 struct btree *replace)
0a63b66db566cf Kent Overstreet 2014-03-17  1499  {
0a63b66db566cf Kent Overstreet 2014-03-17  1500  	struct keylist keys;
0a63b66db566cf Kent Overstreet 2014-03-17  1501  	struct btree *n;
0a63b66db566cf Kent Overstreet 2014-03-17  1502  
0a63b66db566cf Kent Overstreet 2014-03-17  1503  	if (btree_check_reserve(b, NULL))
0a63b66db566cf Kent Overstreet 2014-03-17  1504  		return 0;
0a63b66db566cf Kent Overstreet 2014-03-17  1505  
0a63b66db566cf Kent Overstreet 2014-03-17  1506  	n = btree_node_alloc_replacement(replace, NULL);
0a63b66db566cf Kent Overstreet 2014-03-17  1507  
0a63b66db566cf Kent Overstreet 2014-03-17  1508  	/* recheck reserve after allocating replacement node */
0a63b66db566cf Kent Overstreet 2014-03-17  1509  	if (btree_check_reserve(b, NULL)) {
0a63b66db566cf Kent Overstreet 2014-03-17  1510  		btree_node_free(n);
0a63b66db566cf Kent Overstreet 2014-03-17 @1511  		rw_unlock(true, n);
0a63b66db566cf Kent Overstreet 2014-03-17  1512  		return 0;
0a63b66db566cf Kent Overstreet 2014-03-17  1513  	}
0a63b66db566cf Kent Overstreet 2014-03-17  1514  
0a63b66db566cf Kent Overstreet 2014-03-17  1515  	bch_btree_node_write_sync(n);
0a63b66db566cf Kent Overstreet 2014-03-17  1516  
0a63b66db566cf Kent Overstreet 2014-03-17  1517  	bch_keylist_init(&keys);
0a63b66db566cf Kent Overstreet 2014-03-17  1518  	bch_keylist_add(&keys, &n->key);
0a63b66db566cf Kent Overstreet 2014-03-17  1519  
0a63b66db566cf Kent Overstreet 2014-03-17  1520  	make_btree_freeing_key(replace, keys.top);
0a63b66db566cf Kent Overstreet 2014-03-17  1521  	bch_keylist_push(&keys);
0a63b66db566cf Kent Overstreet 2014-03-17  1522  
0a63b66db566cf Kent Overstreet 2014-03-17  1523  	bch_btree_insert_node(b, op, &keys, NULL, NULL);
0a63b66db566cf Kent Overstreet 2014-03-17  1524  	BUG_ON(!bch_keylist_empty(&keys));
0a63b66db566cf Kent Overstreet 2014-03-17  1525  
0a63b66db566cf Kent Overstreet 2014-03-17  1526  	btree_node_free(replace);
0a63b66db566cf Kent Overstreet 2014-03-17  1527  	rw_unlock(true, n);
0a63b66db566cf Kent Overstreet 2014-03-17  1528  
0a63b66db566cf Kent Overstreet 2014-03-17  1529  	/* Invalidated our iterator */
0a63b66db566cf Kent Overstreet 2014-03-17  1530  	return -EINTR;
0a63b66db566cf Kent Overstreet 2014-03-17  1531  }
0a63b66db566cf Kent Overstreet 2014-03-17  1532  

:::::: The code at line 1511 was first introduced by commit
:::::: 0a63b66db566cffdf90182eb6e66fdd4d0479e63 bcache: Rework btree cache reserve handling

:::::: TO: Kent Overstreet <kmo@daterainc.com>
:::::: CC: Kent Overstreet <kmo@daterainc.com>

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