From: Wei Yang <richard.weiyang@gmail.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Wei Yang <richard.weiyang@gmail.com>,
ying.huang@intel.com, linux-kernel@vger.kernel.org,
linux-mm@kvack.org
Subject: Re: [PATCH 3/3] mm/swapfile.c: count won't be bigger than SWAP_MAP_MAX
Date: Sat, 2 May 2020 13:29:11 +0000 [thread overview]
Message-ID: <20200502132911.u6y6hkh56ik4ojne@master> (raw)
In-Reply-To: <20200501154853.bca4cfb7b2558bd43a4942f3@linux-foundation.org>
On Fri, May 01, 2020 at 03:48:53PM -0700, Andrew Morton wrote:
>On Fri, 1 May 2020 01:52:59 +0000 Wei Yang <richard.weiyang@gmail.com> wrote:
>
>> When the condition is true, there are two possibilities:
>
>I'm struggling with this one.
>
>> 1. count == SWAP_MAP_BAD
>> 2. count == (SWAP_MAP_MAX & COUNT_CONTINUED) == SWAP_MAP_SHMEM
>
>I'm not sure what 2. is trying to say. For a start, (SWAP_MAP_MAX &
>COUNT_CONTINUED) is zero. I guess it meant "|"?
Oops, you are right. It should be (SWAP_MAP_MAX | COUNT_CONTINUED).
Sorry for the confusion.
>
>Also, the return value documentation says we return EINVAL for migration
>entries. Where's that happening, or is the comment out of date?
>
Not paid attention to this.
Take look into the code, I don't find a relationship between the swap count
and migration. Seems we just make a migration entry but not duplicate it.
If my understanding is correct.
>> The first case would be filtered by the first if in __swap_duplicate().
>>
>> And the second case means this swap entry is for shmem. Since we never
>> do another duplication for shmem swap entry. This won't happen neither.
>
--
Wei Yang
Help you, Help me
next prev parent reply other threads:[~2020-05-02 13:29 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-01 1:52 [PATCH 1/3] mm/swapfile.c: classify SWAP_MAP_XXX to make it more readable Wei Yang
2020-05-01 1:52 ` [PATCH 2/3] mm/swapfile.c: __swap_entry_free() always free 1 entry Wei Yang
2020-05-01 1:52 ` [PATCH 3/3] mm/swapfile.c: count won't be bigger than SWAP_MAP_MAX Wei Yang
2020-05-01 22:48 ` Andrew Morton
2020-05-02 13:29 ` Wei Yang [this message]
2020-05-02 13:41 ` Wei Yang
2020-05-06 8:22 ` Huang, Ying
2020-05-07 22:20 ` Wei Yang
2020-05-07 23:48 ` Huang, Ying
2020-05-08 21:19 ` Wei Yang
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