linux-kernel - Re: [akpm-mm:mm-unstable 284/293] mm/khugepaged.c:2409 madvise_collapse() warn: possible memory leak of 'cc'

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Message-ID: <Ys17SBJRS7XaE6nA@google.com>
Date:   Tue, 12 Jul 2022 06:46:48 -0700
From:   Zach O'Keefe <zokeefe@...gle.com>
To:     Dan Carpenter <dan.carpenter@...cle.com>
Cc:     kbuild@...ts.01.org, lkp@...el.com, kbuild-all@...ts.01.org,
        linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linux Memory Management List <linux-mm@...ck.org>
Subject: Re: [akpm-mm:mm-unstable 284/293] mm/khugepaged.c:2409
 madvise_collapse() warn: possible memory leak of 'cc'

On Jul 12 15:35, Dan Carpenter wrote:
> tree:   https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git mm-unstable
> head:   0e9f775fb0b4adf1a4ef50ea156ead09a0fc5194
> commit: 9f626ffb1d1c5c26b4a8e0fdffec784a5f773274 [284/293] mm/madvise: introduce MADV_COLLAPSE sync hugepage collapse
> config: i386-randconfig-m021 (https://download.01.org/0day-ci/archive/20220710/202207100715.TBIYQ4fc-lkp@intel.com/config)
> compiler: gcc-11 (Debian 11.3.0-3) 11.3.0
> 
> If you fix the issue, kindly add following tag where applicable
> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
> 
> smatch warnings:
> mm/khugepaged.c:2409 madvise_collapse() warn: possible memory leak of 'cc'
> 
> vim +/cc +2409 mm/khugepaged.c
> 
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2387  int madvise_collapse(struct vm_area_struct *vma, struct vm_area_struct **prev,
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2388  		     unsigned long start, unsigned long end)
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2389  {
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2390  	struct collapse_control *cc;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2391  	struct mm_struct *mm = vma->vm_mm;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2392  	unsigned long hstart, hend, addr;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2393  	int thps = 0, last_fail = SCAN_FAIL;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2394  	bool mmap_locked = true;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2395  
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2396  	BUG_ON(vma->vm_start > start);
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2397  	BUG_ON(vma->vm_end < end);
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2398  
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2399  	cc = kmalloc(sizeof(*cc), GFP_KERNEL);
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2400  	if (!cc)
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2401  		return -ENOMEM;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2402  	cc->is_khugepaged = false;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2403  	cc->last_target_node = NUMA_NO_NODE;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2404  
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2405  	*prev = vma;
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2406  
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2407  	/* TODO: Support file/shmem */
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06  2408  	if (!vma->anon_vma || !vma_is_anonymous(vma))
> 9f626ffb1d1c5c Zach O'Keefe 2022-07-06 @2409  		return -EINVAL;
> 
> kfree(cc);?
> 
> 
> -- 
> 0-DAY CI Kernel Test Service
> https://01.org/lkp
> 

Yikes. Glad this was caught - my apologies here.

Thanks Dan/lkp!