linux-kernel - Re: [PATCH] mm, oom_reaper: make sure that mmput_async is called only when memory was reaped

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Date:	Tue, 7 Jun 2016 20:30:24 +0800
From:	kbuild test robot <lkp@...el.com>
To:	Michal Hocko <mhocko@...nel.org>
Cc:	kbuild-all@...org, Andrew Morton <akpm@...ux-foundation.org>,
	Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>,
	David Rientjes <rientjes@...gle.com>, linux-mm@...ck.org,
	LKML <linux-kernel@...r.kernel.org>,
	Michal Hocko <mhocko@...e.com>
Subject: Re: [PATCH] mm, oom_reaper: make sure that mmput_async is called
 only when memory was reaped

Hi,

[auto build test WARNING on next-20160607]
[cannot apply to v4.7-rc2 v4.7-rc1 v4.6-rc7 v4.7-rc2]
[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/Michal-Hocko/mm-oom_reaper-make-sure-that-mmput_async-is-called-only-when-memory-was-reaped/20160607-211715
config: mn10300-asb2364_defconfig (attached as .config)
compiler: am33_2.0-linux-gcc (GCC) 4.9.0
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        make.cross ARCH=mn10300 

All warnings (new ones prefixed by >>):

   mm/oom_kill.c: In function '__oom_reap_task':
>> mm/oom_kill.c:490:7: warning: passing argument 1 of 'mmget_not_zero' from incompatible pointer type
     if (!mmget_not_zero(&mm->mm_users)) {
          ^
   In file included from include/linux/oom.h:5:0,
                    from mm/oom_kill.c:20:
   include/linux/sched.h:2746:20: note: expected 'struct mm_struct *' but argument is of type 'struct atomic_t *'
    static inline bool mmget_not_zero(struct mm_struct *mm)
                       ^

vim +/mmget_not_zero +490 mm/oom_kill.c

   474		if (!p)
   475			goto unlock_oom;
   476		mm = p->mm;
   477		atomic_inc(&mm->mm_count);
   478		task_unlock(p);
   479	
   480		if (!down_read_trylock(&mm->mmap_sem)) {
   481			ret = false;
   482			goto mm_drop;
   483		}
   484	
   485		/*
   486		 * increase mm_users only after we know we will reap something so
   487		 * that the mmput_async is called only when we have reaped something
   488		 * and delayed __mmput doesn't matter that much
   489		 */
 > 490		if (!mmget_not_zero(&mm->mm_users)) {
   491			up_read(&mm->mmap_sem);
   492			goto mm_drop;
   493		}
   494	
   495		tlb_gather_mmu(&tlb, mm, 0, -1);
   496		for (vma = mm->mmap ; vma; vma = vma->vm_next) {
   497			if (is_vm_hugetlb_page(vma))
   498				continue;

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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