From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f70.google.com (mail-pg0-f70.google.com [74.125.83.70]) by kanga.kvack.org (Postfix) with ESMTP id 3842A6B03ED for ; Tue, 9 May 2017 05:30:21 -0400 (EDT) Received: by mail-pg0-f70.google.com with SMTP id u187so89954674pgb.0 for ; Tue, 09 May 2017 02:30:21 -0700 (PDT) Received: from szxga01-in.huawei.com (szxga01-in.huawei.com. [45.249.212.187]) by mx.google.com with ESMTPS id l184si12626145pga.236.2017.05.09.02.30.19 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 09 May 2017 02:30:20 -0700 (PDT) Message-ID: <59118B04.1070404@huawei.com> Date: Tue, 9 May 2017 17:25:24 +0800 From: zhong jiang MIME-Version: 1.0 Subject: Re: [PATCH] mm: fix the memory leak after collapsing the huge page fails References: <1494317557-49680-1-git-send-email-zhongjiang@huawei.com> <7d5fd103-f997-e445-2ce6-2e44deed33d8@suse.cz> In-Reply-To: <7d5fd103-f997-e445-2ce6-2e44deed33d8@suse.cz> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Vlastimil Babka Cc: akpm@linux-foundation.org, mgorman@techsingularity.net, hannes@cmpxchg.org, kirill.shutemov@linux.intel.com, linux-mm@kvack.org On 2017/5/9 16:42, Vlastimil Babka wrote: > On 05/09/2017 10:12 AM, zhongjiang wrote: >> From: zhong jiang >> >> Current, when we prepare a huge page to collapse, due to some >> reasons, it can fail to collapse. At the moment, we should >> release the preallocate huge page. > Yeah, looks like the leak is there... > >> Signed-off-by: zhong jiang >> --- >> mm/khugepaged.c | 1 + >> 1 file changed, 1 insertion(+) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index 7cb9c88..3f5749e 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -1080,6 +1080,7 @@ static void collapse_huge_page(struct mm_struct *mm, >> result = SCAN_SUCCEED; >> out_up_write: >> up_write(&mm->mmap_sem); >> + put_page(new_page); > This doesn't seem correct. > - the put_page() will be called also on success, so a premature free? my God, I forget this. > - the out_nolock: case should be also handled khugepage_alloc_page fails . it also will reach out_nolock. The out_nolock is very mess, need to reconsider. > - collapse_shmem() seems to have the same problem yes. I will add the path to fix. >> out_nolock: >> trace_mm_collapse_huge_page(mm, isolated, result); >> return; >> > > . > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org