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

[Yang Shi]

On Tue, Jul 12, 2022 at 5:36 AM Dan Carpenter <dan.carpenter@xxxxxxxxxx> 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@xxxxxxxxx/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@xxxxxxxxx>
> Reported-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
>
> 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;

It seems better to move the cc kmalloc after the anonymous vma check?

>
> kfree(cc);?
>
>
> --
> 0-DAY CI Kernel Test Service
> https://01.org/lkp
>
>