From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f197.google.com (mail-wr0-f197.google.com [209.85.128.197]) by kanga.kvack.org (Postfix) with ESMTP id D638D2806D7 for ; Tue, 9 May 2017 08:55:41 -0400 (EDT) Received: by mail-wr0-f197.google.com with SMTP id u96so19785381wrc.7 for ; Tue, 09 May 2017 05:55:41 -0700 (PDT) Received: from szxga03-in.huawei.com (szxga03-in.huawei.com. [45.249.212.189]) by mx.google.com with ESMTPS id y3si2653561ljd.291.2017.05.09.05.55.38 for (version=TLS1 cipher=AES128-SHA bits=128/128); Tue, 09 May 2017 05:55:40 -0700 (PDT) Message-ID: <5911B40D.2020007@huawei.com> Date: Tue, 9 May 2017 20:20:29 +0800 From: zhong jiang MIME-Version: 1.0 Subject: Re: [PATCH v2] mm: fix the memory leak after collapsing the huge page fails References: <1494327305-835-1-git-send-email-zhongjiang@huawei.com> <442638e9-d6db-2f1c-e260-9290d7524f1d@suse.cz> In-Reply-To: <442638e9-d6db-2f1c-e260-9290d7524f1d@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, kirill.shutemov@linux.intel.com, hannes@cmpxchg.org, mgorman@techsingularity.net, linux-mm@kvack.org On 2017/5/9 19:34, Vlastimil Babka wrote: > On 05/09/2017 12:55 PM, 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. >> >> Signed-off-by: zhong jiang > Hmm, scratch that, there's no memory leak. The pointer to new_page is > stored in *hpage, and put_page() is called all the way up in > khugepaged_do_scan(). I see. I miss it. but why the new_page need to be release all the way. I do not see the count increment when scan success. it save the memory, only when page fault happen. Thanks zhongjiang >> --- >> mm/khugepaged.c | 4 ++++ >> 1 file changed, 4 insertions(+) >> >> diff --git a/mm/khugepaged.c b/mm/khugepaged.c >> index 7cb9c88..586b1f1 100644 >> --- a/mm/khugepaged.c >> +++ b/mm/khugepaged.c >> @@ -1082,6 +1082,8 @@ static void collapse_huge_page(struct mm_struct *mm, >> up_write(&mm->mmap_sem); >> out_nolock: >> trace_mm_collapse_huge_page(mm, isolated, result); >> + if (page != NULL && result != SCAN_SUCCEED) >> + put_page(new_page); >> return; >> out: >> mem_cgroup_cancel_charge(new_page, memcg, true); >> @@ -1555,6 +1557,8 @@ static void collapse_shmem(struct mm_struct *mm, >> } >> out: >> VM_BUG_ON(!list_empty(&pagelist)); >> + if (page != NULL && result != SCAN_SUCCEED) >> + put_page(new_page); >> /* TODO: tracepoints */ >> } >> >> > > . > -- 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