From: Vlastimil Babka <vbabka@suse.cz>
To: "Kirill A. Shutemov" <kirill@shutemov.name>,
Michal Hocko <mhocko@kernel.org>
Cc: kirill.shutemov@linux.intel.com,
Yang Shi <yang.shi@linux.alibaba.com>,
hannes@cmpxchg.org, rientjes@google.com,
akpm@linux-foundation.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: Re: [v2 PATCH -mm] mm: account deferred split THPs into MemAvailable
Date: Tue, 27 Aug 2019 14:01:56 +0200 [thread overview]
Message-ID: <aaaf9742-56f7-44b7-c3db-ad078b7b2220@suse.cz> (raw)
In-Reply-To: <20190827110210.lpe36umisqvvesoa@box>
On 8/27/19 1:02 PM, Kirill A. Shutemov wrote:
> On Tue, Aug 27, 2019 at 08:01:39AM +0200, Michal Hocko wrote:
>> On Mon 26-08-19 16:15:38, Kirill A. Shutemov wrote:
>>>
>>> Unmapped completely pages will be freed with current code. Deferred split
>>> only applies to partly mapped THPs: at least on 4k of the THP is still
>>> mapped somewhere.
>>
>> Hmm, I am probably misreading the code but at least current Linus' tree
>> reads page_remove_rmap -> [page_remove_anon_compound_rmap ->\ deferred_split_huge_page even
>> for fully mapped THP.
>
> Well, you read correctly, but it was not intended. I screwed it up at some
> point.
>
> See the patch below. It should make it work as intened.
>
> It's not bug as such, but inefficientcy. We add page to the queue where
> it's not needed.
But that adding to queue doesn't affect whether the page will be freed
immediately if there are no more partial mappings, right? I don't see
deferred_split_huge_page() pinning the page.
So your patch wouldn't make THPs freed immediately in cases where they
haven't been freed before immediately, it just fixes a minor
inefficiency with queue manipulation?
next prev parent reply other threads:[~2019-08-27 12:02 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-21 17:55 Yang Shi
2019-08-22 8:04 ` Michal Hocko
2019-08-22 12:56 ` Vlastimil Babka
2019-08-22 15:29 ` Kirill A. Shutemov
2019-08-26 7:40 ` Michal Hocko
2019-08-26 13:15 ` Kirill A. Shutemov
2019-08-27 6:01 ` Michal Hocko
2019-08-27 11:02 ` Kirill A. Shutemov
2019-08-27 11:48 ` Michal Hocko
2019-08-27 12:01 ` Vlastimil Babka [this message]
2019-08-27 12:09 ` Michal Hocko
2019-08-27 12:17 ` Kirill A. Shutemov
2019-08-27 12:59 ` Kirill A. Shutemov
2019-08-27 17:06 ` Yang Shi
2019-08-28 7:57 ` Michal Hocko
2019-08-28 14:03 ` Kirill A. Shutemov
[not found] ` <20190828141253.GM28313@dhcp22.suse.cz>
2019-08-28 14:46 ` Kirill A. Shutemov
2019-08-28 16:02 ` Michal Hocko
2019-08-29 17:03 ` Yang Shi
2019-08-30 6:23 ` Michal Hocko
2019-08-30 12:53 ` Kirill A. Shutemov
2019-08-22 15:49 ` Kirill A. Shutemov
2019-08-22 15:57 ` Yang Shi
2019-08-22 15:33 ` Yang Shi
2019-08-26 7:43 ` Michal Hocko
2019-08-27 4:27 ` Yang Shi
2019-08-27 5:59 ` Michal Hocko
2019-08-27 8:32 ` Kirill A. Shutemov
2019-08-27 9:00 ` Michal Hocko
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