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From: Matthew Wilcox <willy@infradead.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Hugh Dickins <hughd@google.com>,
	David Hildenbrand <david@redhat.com>,
	Yang Shi <shy828301@gmail.com>, Linux-MM <linux-mm@kvack.org>,
	LKML <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>,
	huang ying <huang.ying.caritas@gmail.com>
Subject: Re: [PATCH] mm,shmem: Fix a typo in shmem_swapin_page()
Date: Tue, 3 Aug 2021 12:59:10 +0100	[thread overview]
Message-ID: <YQkvjng6ljwtp9eb@casper.infradead.org> (raw)
In-Reply-To: <877dh354vc.fsf@yhuang6-desk2.ccr.corp.intel.com>

On Tue, Aug 03, 2021 at 04:06:47PM +0800, Huang, Ying wrote:
> As Hugh pointed out, EINVAL isn't an appropriate error code for race
> condition.  After checking the code, I found that EEXIST is the error
> code used for race condition.  So I revise the patch as below.  If Hugh
> doesn't object, can you help to replace the patch with the below one?
> 
> Best Regards,
> Huang, Ying
> 
> -----------------------------8<---------------------------------------
> >From e2b281a0b09d34d6463942e214e577ed9357c213 Mon Sep 17 00:00:00 2001
> From: Huang Ying <ying.huang@intel.com>
> Date: Tue, 3 Aug 2021 10:51:16 +0800
> Subject: [PATCH] shmem_swapin_page(): fix error processing for
>  get_swap_device()
> 
> Firstly, "-" is missing before the error code.  Secondly, EINVAL isn't
> the proper error code for the race condition.  EEXIST is used in
> shmem_swapin_page() for that.  So the error code is changed to EEXIST
> too.
> 
> Link: https://lkml.kernel.org/r/20210723080000.93953-1-ying.huang@intel.com
> Fixes: 2efa33fc7f6e ("mm/shmem: fix shmem_swapin() race with swapoff")
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>

Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Also, the description is poor.  How about:

If we hit this rare race, returning EINVAL (or even -EINVAL) would cause
the page fault to be handled as a SIGBUS.  This is not correct; the page
is not missing or unreadable, it has simply changed location.  Returning
-EEXIST here will cause the lookup to be retried by the caller.


  reply	other threads:[~2021-08-03 12:00 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-07-23  8:00 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
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 [this message]
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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