Re: [PATCH v2] mm: workingset: fix NULL ptr dereference

From: kbuild test robot <lkp@intel.com>
To: Minchan Kim <minchan@kernel.org>
Cc: kbuild-all@01.org, Matthew Wilcox <willy@infradead.org>,
	Chao Yu <yuchao0@huawei.com>, Jaegeuk Kim <jaegeuk@kernel.org>,
	Christopher Lameter <cl@linux.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	linux-mm <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Johannes Weiner <hannes@cmpxchg.org>, Jan Kara <jack@suse.cz>,
	Chris Fries <cfries@google.com>,
	linux-f2fs-devel@lists.sourceforge.net,
	linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v2] mm: workingset: fix NULL ptr dereference
Date: Tue, 10 Apr 2018 21:11:35 +0800	[thread overview]
Message-ID: <201804102116.2TH1yH5I%fengguang.wu@intel.com> (raw)
In-Reply-To: <20180410023339.GB214542@rodete-desktop-imager.corp.google.com>

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Hi Minchan,

I love your patch! Yet something to improve:

[auto build test ERROR on linus/master]
[also build test ERROR on v4.16 next-20180410]
[if your patch is applied to the wrong git tree, please drop us a note to help improve the system]

url:    https://github.com/0day-ci/linux/commits/Minchan-Kim/mm-workingset-fix-NULL-ptr-dereference/20180410-163500
config: i386-randconfig-a0-201814 (attached as .config)
compiler: gcc-4.9 (Debian 4.9.4-2) 4.9.4
reproduce:
        # save the attached .config to linux build tree
        make ARCH=i386 

All errors (new ones prefixed by >>):

   lib/radix-tree.c: In function 'radix_tree_preload':
>> lib/radix-tree.c:522:16: error: 'GFP_ZERO' undeclared (first use in this function)
      gfp_mask &= ~GFP_ZERO
                   ^
   lib/radix-tree.c:522:16: note: each undeclared identifier is reported only once for each function it appears in
   lib/radix-tree.c:524:2: error: expected ';' before 'return'
     return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
     ^
   lib/radix-tree.c:525:1: warning: control reaches end of non-void function [-Wreturn-type]
    }
    ^

vim +/GFP_ZERO +522 lib/radix-tree.c

   500	
   501	/*
   502	 * Load up this CPU's radix_tree_node buffer with sufficient objects to
   503	 * ensure that the addition of a single element in the tree cannot fail.  On
   504	 * success, return zero, with preemption disabled.  On error, return -ENOMEM
   505	 * with preemption not disabled.
   506	 *
   507	 * To make use of this facility, the radix tree must be initialised without
   508	 * __GFP_DIRECT_RECLAIM being passed to INIT_RADIX_TREE().
   509	 */
   510	int radix_tree_preload(gfp_t gfp_mask)
   511	{
   512		/* Warn on non-sensical use... */
   513		WARN_ON_ONCE(!gfpflags_allow_blocking(gfp_mask));
   514		/*
   515		 * New allocate node must have node->private_list as INIT_LIST_HEAD
   516		 * state by workingset shadow memory implementation.
   517		 * If user pass  __GFP_ZERO by mistake, slab allocator will clear
   518		 * node->private_list, which makes a BUG. Rather than going Oops,
   519		 * just fix and warn about it.
   520		 */
   521		if (WARN_ON(gfp_mask & __GFP_ZERO))
 > 522			gfp_mask &= ~GFP_ZERO
   523	
   524		return __radix_tree_preload(gfp_mask, RADIX_TREE_PRELOAD_SIZE);
   525	}
   526	EXPORT_SYMBOL(radix_tree_preload);
   527	

---
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