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From: Andrew Morton <akpm@linux-foundation.org>
To: kernel test robot <lkp@intel.com>
Cc: Linux Memory Management List <linux-mm@kvack.org>,
	Chinwen Chang <chinwen.chang@mediatek.com>
Subject: Re: [linux-next:master] BUILD REGRESSION 605cbf3d5f20470ec303b79feda3202935f4a142
Date: Thu, 20 Aug 2020 13:43:05 -0700	[thread overview]
Message-ID: <20200820134305.baa5ac2c1300a6b412a0c7c9@linux-foundation.org> (raw)
In-Reply-To: <5f3edc64.qkHsk6Qli55TwDHw%lkp@intel.com>

On Fri, 21 Aug 2020 04:26:12 +0800 kernel test robot <lkp@intel.com> wrote:

> tree/branch: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git  master
> branch HEAD: 605cbf3d5f20470ec303b79feda3202935f4a142  Add linux-next specific files for 20200820
> 
> Error/Warning in current branch:

> ...
>
> 
> fs/proc/task_mmu.c:947 show_smaps_rollup() error: double unlocked 'mm->mmap_lock' (orig line 879)

This is code added by "mm: proc: smaps_rollup: do not stall write
attempts on mmap_lock"
(http://lkml.kernel.org/r/1597715898-3854-4-git-send-email-chinwen.chang@mediatek.com).

I don't get it.

: 		if (mmap_lock_is_contended(mm)) {
: 			mmap_read_unlock(mm);
: 			ret = mmap_read_lock_killable(mm);
: 			if (ret) {
: 				release_task_mempolicy(priv);
: 				goto out_put_mm;
: 			}

Here the mmap_lock is again taken for read

:		...
:
: 		}
: 		/* Case 2 above */
: 		vma = vma->vm_next;
: 	}
: 
: 	...
:
: 	mmap_read_unlock(mm);

and here it's unlocked.  I don't see a possibility for double-unlock?


  parent reply	other threads:[~2020-08-20 20:43 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-20 20:26 kernel test robot
2020-08-20 20:40 ` Andrew Morton
2020-08-20 21:03   ` Amir Goldstein
2020-08-20 20:43 ` Andrew Morton [this message]
2020-08-23  3:41   ` Philip Li

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