From: Bob Liu <lliubbo@gmail.com>
To: Weijie Yang <weijie.yang@samsung.com>
Cc: Minchan Kim <minchan@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Seth Jennings <sjenning@linux.vnet.ibm.com>,
Bob Liu <bob.liu@oracle.com>,
Weijie Yang <weijie.yang.kh@gmail.com>,
Linux-MM <linux-mm@kvack.org>,
Linux-Kernel <linux-kernel@vger.kernel.org>,
stable@vger.kernel.org, d.j.shin@samsung.com,
heesub.shin@samsung.com,
Kyungmin Park <kyungmin.park@samsung.com>,
hau.chen@samsung.com, bifeng.tong@samsung.com,
rui.xie@samsung.com
Subject: Re: [PATCH v3 2/3] mm/zswap: bugfix: memory leak when invalidate and reclaim occur concurrently
Date: Sat, 12 Oct 2013 10:32:31 +0800 [thread overview]
Message-ID: <CAA_GA1dE+Cw+bi=+Kr=BHSW5Xe71M5KN_sApOzkHiHWeriqOFw@mail.gmail.com> (raw)
In-Reply-To: <000001ceba6a$997d0490$cc770db0$%yang@samsung.com>
On Thu, Sep 26, 2013 at 11:42 AM, Weijie Yang <weijie.yang@samsung.com> wrote:
> On Tue, Sep 24, 2013 at 9:03 AM, Minchan Kim <minchan@kernel.org> wrote:
>> On Mon, Sep 23, 2013 at 04:21:49PM +0800, Weijie Yang wrote:
>> >
>> > Modify:
>> > - check the refcount in fail path, free memory if it is not referenced.
>>
>> Hmm, I don't like this because zswap refcount routine is already mess for me.
>> I'm not sure why it was designed from the beginning. I hope we should fix it first.
>>
>> 1. zswap_rb_serach could include zswap_entry_get semantic if it founds a entry from
>> the tree. Of course, we should ranme it as find_get_zswap_entry like find_get_page.
>> 2. zswap_entry_put could hide resource free function like zswap_free_entry so that
>> all of caller can use it easily following pattern.
>>
>> find_get_zswap_entry
>> ...
>> ...
>> zswap_entry_put
>>
>> Of course, zswap_entry_put have to check the entry is in the tree or not
>> so if someone already removes it from the tree, it should avoid double remove.
>>
>> One of the concern I can think is that approach extends critical section
>> but I think it would be no problem because more bottleneck would be [de]compress
>> functions. If it were really problem, we can mitigate a problem with moving
>> unnecessary functions out of zswap_free_entry because it seem to be rather
>> over-enginnering.
>
> I refactor the zswap refcount routine according to Minchan's idea.
> Here is the new patch, Any suggestion is welcomed.
>
> To Seth and Bob, would you please review it again?
>
I have nothing in addition to Minchan's review.
Since the code is a bit complex, I'd suggest you to split it into two patches.
[1/2]: fix the memory leak
[2/2]: clean up the entry_put
And run some testing..
Thanks,
-Bob
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next prev parent reply other threads:[~2013-10-12 2:32 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-09-23 8:21 Weijie Yang
2013-09-24 1:03 ` Minchan Kim
2013-09-26 3:42 ` Weijie Yang
2013-10-10 19:54 ` Andrew Morton
2013-10-11 7:13 ` Minchan Kim
2013-10-12 2:50 ` Bob Liu
2013-10-12 9:14 ` Weijie Yang
2013-10-12 9:29 ` Bob Liu
2013-10-12 8:41 ` Weijie Yang
2013-10-12 9:37 ` Weijie Yang
2013-10-14 0:31 ` Minchan Kim
2013-10-14 8:05 ` Weijie Yang
2013-10-12 2:32 ` Bob Liu [this message]
2013-10-12 8:45 ` Weijie Yang
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