From: Miaohe Lin <linmiaohe@huawei.com>
To: riteshh <riteshh@linux.ibm.com>
Cc: <akpm@linux-foundation.org>, <hannes@cmpxchg.org>,
<mhocko@suse.com>, <iamjoonsoo.kim@lge.com>, <vbabka@suse.cz>,
<alex.shi@linux.alibaba.com>, <willy@infradead.org>,
<minchan@kernel.org>, <richard.weiyang@gmail.com>,
<ying.huang@intel.com>, <hughd@google.com>,
<tim.c.chen@linux.intel.com>, <linux-kernel@vger.kernel.org>,
<linux-mm@kvack.org>
Subject: Re: [PATCH 0/5] close various race windows for swap
Date: Fri, 9 Apr 2021 16:01:23 +0800 [thread overview]
Message-ID: <48892512-c2f7-9898-0373-a185975b456c@huawei.com> (raw)
In-Reply-To: <20210408145517.jqodfz6cmm4wwk7g@riteshh-domain>
On 2021/4/8 22:55, riteshh wrote:
> On 21/04/08 09:08AM, Miaohe Lin wrote:
>> Hi all,
>> When I was investigating the swap code, I found some possible race
>> windows. This series aims to fix all these races. But using current
>> get/put_swap_device() to guard against concurrent swapoff for
>> swap_readpage() looks terrible because swap_readpage() may take really
>> long time. And to reduce the performance overhead on the hot-path as
>> much as possible, it appears we can use the percpu_ref to close this
>> race window(as suggested by Huang, Ying). The patch 1 adds percpu_ref
>> support for swap and the rest of the patches use this to close various
>> race windows. More details can be found in the respective changelogs.
>> Thanks!
>>
>> Miaohe Lin (5):
>> mm/swapfile: add percpu_ref support for swap
>> swap: fix do_swap_page() race with swapoff
>> mm/swap_state: fix get_shadow_from_swap_cache() race with swapoff
>> mm/swap_state: fix potential faulted in race in swap_ra_info()
>> mm/swap_state: fix swap_cluster_readahead() race with swapoff
>
Many thanks for quick respond.
> Somehow I see Patch-1 and Patch-2 are missing on linux-mm[1].
I have no idea why Patch-1 and Patch-2 are missing. But they could be found at:
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2542188.html
> Also I wanted to ask if you have a way to trigger this in a more controlled
> environment (consistently)?
>
This is *theoretical* issue. The race window is very small but not impossible.
Please see the discussion:
https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg2530094.html
> [1]: https://patchwork.kernel.org/project/linux-mm/cover/20210408130820.48233-1-linmiaohe@huawei.com/
>
Thanks again.
> -ritesh
>
>>
>> include/linux/swap.h | 4 +++-
>> mm/memory.c | 10 +++++++++
>> mm/swap_state.c | 33 +++++++++++++++++++++--------
>> mm/swapfile.c | 50 +++++++++++++++++++++++++++-----------------
>> 4 files changed, 68 insertions(+), 29 deletions(-)
>>
>> --
>> 2.19.1
>>
>>
> .
>
prev parent reply other threads:[~2021-04-09 8:01 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-04-08 13:08 [PATCH 0/5] close various race windows for swap Miaohe Lin
2021-04-08 13:08 ` [PATCH 1/5] mm/swapfile: add percpu_ref support " Miaohe Lin
2021-04-12 3:30 ` Huang, Ying
2021-04-12 6:59 ` Miaohe Lin
2021-04-12 7:24 ` Huang, Ying
2021-04-13 12:39 ` Miaohe Lin
2021-04-14 1:17 ` Huang, Ying
2021-04-14 1:58 ` Miaohe Lin
2021-04-14 2:06 ` Huang, Ying
2021-04-14 3:44 ` Dennis Zhou
2021-04-14 3:59 ` Huang, Ying
2021-04-14 4:05 ` Dennis Zhou
2021-04-14 5:44 ` Huang, Ying
2021-04-14 14:53 ` Dennis Zhou
2021-04-15 3:16 ` Miaohe Lin
2021-04-15 4:20 ` Dennis Zhou
2021-04-15 9:17 ` Miaohe Lin
2021-04-15 5:24 ` Huang, Ying
2021-04-15 14:31 ` Dennis Zhou
2021-04-16 0:54 ` Huang, Ying
2021-04-16 2:27 ` Miaohe Lin
2021-04-16 6:25 ` Huang, Ying
2021-04-16 8:30 ` Miaohe Lin
2021-04-08 13:08 ` [PATCH 2/5] swap: fix do_swap_page() race with swapoff Miaohe Lin
2021-04-08 21:34 ` Tim Chen
2021-04-09 8:42 ` Miaohe Lin
2021-04-09 17:17 ` Tim Chen
2021-04-10 3:17 ` Miaohe Lin
2021-04-12 1:44 ` Huang, Ying
2021-04-12 3:24 ` Miaohe Lin
2021-04-13 1:27 ` Huang, Ying
2021-04-13 19:24 ` Tim Chen
2021-04-14 1:04 ` Huang, Ying
2021-04-14 2:20 ` Miaohe Lin
2021-04-14 16:13 ` Tim Chen
2021-04-15 3:19 ` Miaohe Lin
2021-04-14 2:55 ` Miaohe Lin
2021-04-14 3:07 ` Huang, Ying
2021-04-14 3:27 ` Miaohe Lin
2021-04-08 13:08 ` [PATCH 3/5] mm/swap_state: fix get_shadow_from_swap_cache() " Miaohe Lin
2021-04-13 1:33 ` Huang, Ying
2021-04-14 2:42 ` Miaohe Lin
2021-04-08 13:08 ` [PATCH 4/5] mm/swap_state: fix potential faulted in race in swap_ra_info() Miaohe Lin
2021-04-09 8:50 ` Huang, Ying
2021-04-09 9:00 ` Miaohe Lin
2021-04-12 0:55 ` Huang, Ying
2021-04-12 3:17 ` Miaohe Lin
2021-04-08 13:08 ` [PATCH 5/5] mm/swap_state: fix swap_cluster_readahead() race with swapoff Miaohe Lin
2021-04-13 1:36 ` Huang, Ying
2021-04-14 2:43 ` Miaohe Lin
2021-04-08 14:55 ` [PATCH 0/5] close various race windows for swap riteshh
2021-04-09 8:01 ` Miaohe Lin [this message]
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