From: "Huang, Ying" <ying.huang@intel.com>
To: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
David Hildenbrand <david@redhat.com>,
Yang Shi <shy828301@gmail.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Miaohe Lin <linmiaohe@huawei.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@suse.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Minchan Kim <minchan@kernel.org>
Subject: Re: [PATCH] mm,shmem: Fix a typo in shmem_swapin_page()
Date: Wed, 04 Aug 2021 17:04:20 +0800 [thread overview]
Message-ID: <875ywl4m3v.fsf@yhuang6-desk2.ccr.corp.intel.com> (raw)
In-Reply-To: <704d597-443b-32f-84eb-524a58dd8ef@google.com> (Hugh Dickins's message of "Tue, 3 Aug 2021 22:34:52 -0700 (PDT)")
Hugh Dickins <hughd@google.com> writes:
> On Tue, 3 Aug 2021, Matthew Wilcox wrote:
>> On Tue, Aug 03, 2021 at 04:14:38PM +0800, Huang, Ying wrote:
>> > Matthew Wilcox <willy@infradead.org> writes:
>> > > But I REALLY REALLY REALLY want a reproducer. Right now, I have a hard
>> > > time believing this, or any of the other races can really happen.
>> >
>> > I think the race is only theoretical too. Firstly, swapoff is a rare
>> > operations in practice; secondly, the race window is really small.
>>
>> So do something to provoke it. Widen the window. Put an msleep(1000)
>> between *pagep = NULL and the call to get_swap_device(). That's assuming
>> that the swapon/swapoff loop that I proposed doesn't work. Did you
>> try it?
>
> I've been doing that swapon/swapoff loop for years, while running kernel
> builds on tmpfs going out to swap; for better or worse on baremetal not VM.
>
> You're right that few will ever need that level of reliability; but it
> has caught problems from time to time, and I do insist on fixing them.
>
> I'm not as insistent as you on wanting a reproducer; and we all take pride
> sometimes in fixing ever more inconceivable bugs. I'm not against that,
> but it's easy to end up with a fix more dangerous than what it claims to
> fix, rather like with random newbie cleanups.
Yes. I totally agree, bug fixing is hard.
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2021-08-04 9:04 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-23 8:00 [PATCH] mm,shmem: Fix a typo in shmem_swapin_page() Huang Ying
2021-07-23 11:10 ` David Hildenbrand
2021-07-23 20:23 ` Hugh Dickins
2021-07-23 21:53 ` Matthew Wilcox
2021-08-03 8:14 ` Huang, Ying
2021-08-03 12:01 ` Matthew Wilcox
2021-08-04 5:34 ` Hugh Dickins
2021-08-04 9:04 ` Huang, Ying [this message]
2021-08-05 23:08 ` Yang Shi
2021-08-06 6:01 ` Hugh Dickins
2021-08-06 20:37 ` Yang Shi
2021-08-09 21:26 ` Yang Shi
2021-08-09 23:43 ` Huang, Ying
2021-08-10 1:11 ` Yang Shi
2021-08-04 9:01 ` Huang, Ying
2021-07-28 13:03 ` huang ying
2021-08-03 8:06 ` Huang, Ying
2021-08-03 11:59 ` Matthew Wilcox
2021-08-04 4:28 ` Hugh Dickins
2021-08-04 6:42 ` Hugh Dickins
2021-08-04 8:59 ` Huang, Ying
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