From: Vlastimil Babka <vbabka@suse.cz>
To: Hugh Dickins <hughd@google.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>,
akpm@linux-foundation.org, mgorman@techsingularity.net,
tj@kernel.org, khlebnikov@yandex-team.ru,
daniel.m.jordan@oracle.com, willy@infradead.org,
hannes@cmpxchg.org, lkp@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, cgroups@vger.kernel.org,
shakeelb@google.com, iamjoonsoo.kim@lge.com,
richard.weiyang@gmail.com, kirill@shutemov.name,
alexander.duyck@gmail.com, rong.a.chen@intel.com,
mhocko@suse.com, vdavydov.dev@gmail.com, shy828301@gmail.com,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH v21 14/19] mm/lru: introduce TestClearPageLRU
Date: Thu, 12 Nov 2020 12:24:17 +0100 [thread overview]
Message-ID: <057bb8c8-3993-5638-42e9-f58d72f21b9e@suse.cz> (raw)
In-Reply-To: <alpine.LSU.2.11.2011111729350.2174@eggly.anvils>
On 11/12/20 3:03 AM, Hugh Dickins wrote:
> On Wed, 11 Nov 2020, Vlastimil Babka wrote:
>> On 11/5/20 9:55 AM, Alex Shi wrote:
>>
>> > --- a/mm/vmscan.c
>> > +++ b/mm/vmscan.c
>> > @@ -1542,7 +1542,7 @@ unsigned int reclaim_clean_pages_from_list(struct
>> > zone *zone,
>> > */
>> > int __isolate_lru_page(struct page *page, isolate_mode_t mode)
>> > {
>> > - int ret = -EINVAL;
>> > + int ret = -EBUSY;
>> > /* Only take pages on the LRU. */
>> > if (!PageLRU(page))
>> > @@ -1552,8 +1552,6 @@ int __isolate_lru_page(struct page *page,
>> > isolate_mode_t mode)
>> > if (PageUnevictable(page) && !(mode & ISOLATE_UNEVICTABLE))
>> > return ret;
>> > - ret = -EBUSY;
>>
>> I'm not sure why this change is here, looks unrelated to the patch?
>>
>> Oh I see, you want to prevent the BUG() in isolate_lru_pages().
>
> Yes, I suggested this part of the patch to Alex, when I hit that BUG().
>
>>
>> But due to that, the PageUnevictable check was also affected unintentionally.
>> But I don't think it's that important to BUG() when we run into
>> PageUnevictable unexpectedly, so that's probably ok.
>
> Not unintentional. __isolate_lru_page(), or __isolate_lru_page_prepare(),
> is a silly function, used by two callers whose requirements are almost
> entirely disjoint. The ISOLATE_UNEVICTABLE case is only for compaction.c,
> which takes no interest in -EINVAL versus -EBUSY, and has no such BUG().
>
> I think it dates back to lumpy reclaim days, and it probably made more
> sense back then.
Ah, thanks for explaining.
>>
>> But with that, we can just make __isolate_lru_page() a bool function and
>> remove the ugly switch in isolate_lru_pages()?
>
> I agree that the switch statement in isolate_lru_pages() seems pointless
> now, and can be turned into an if{}else{}. But that cleanup is a
> diversion from this particular TestClearPageLRU patch, and I think from
> the whole series (checking final state of the patchset, yes, the switch
> is still there - though I think there have been variant series which
> removed it).
>
> Can we please leave that cleanup until after the series has gone in?
Sure thing!
The patch seems functionally fine, so
Acked-by: Vlastimil Babka <vbabka@suse.cz>
> I think several of us have cleanups or optimization that we want to
> follow (I had one that inlines what isolate_migratepages_block() wanted
> of __isolate_lru_page() into that function, so simplifying what vmscan.c
> needs; perhaps that can now eliminate it completely, I've not tried
> recently). But there was a point at which the series was growing
> ten patches per release as we all added our bits and pieces on top,
> it got harder and harder to review the whole, and further from
> getting the basics in: I do push back against that tendency.
>
> Hugh
>
next prev parent reply other threads:[~2020-11-12 11:24 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-05 8:55 [PATCH v21 00/19] per memcg lru lock Alex Shi
2020-11-05 8:55 ` [PATCH v21 01/19] mm/thp: move lru_add_page_tail func to huge_memory.c Alex Shi
2020-11-05 8:55 ` [PATCH v21 02/19] mm/thp: use head for head page in lru_add_page_tail Alex Shi
2020-11-05 8:55 ` [PATCH v21 03/19] mm/thp: Simplify lru_add_page_tail() Alex Shi
2020-11-05 8:55 ` [PATCH v21 04/19] mm/thp: narrow lru locking Alex Shi
2020-11-05 8:55 ` [PATCH v21 05/19] mm/vmscan: remove unnecessary lruvec adding Alex Shi
2020-11-11 12:36 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 06/19] mm/rmap: stop store reordering issue on page->mapping Alex Shi
2020-11-06 1:20 ` Alex Shi
2020-11-10 19:06 ` Johannes Weiner
2020-11-11 7:41 ` Hugh Dickins
2020-11-05 8:55 ` [PATCH v21 07/19] mm: page_idle_get_page() does not need lru_lock Alex Shi
2020-11-10 19:01 ` Johannes Weiner
2020-11-11 8:17 ` huang ying
2020-11-11 12:52 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 08/19] mm/memcg: add debug checking in lock_page_memcg Alex Shi
2020-11-05 8:55 ` [PATCH v21 09/19] mm/swap.c: fold vm event PGROTATED into pagevec_move_tail_fn Alex Shi
2020-11-05 8:55 ` [PATCH v21 10/19] mm/lru: move lock into lru_note_cost Alex Shi
2020-11-05 8:55 ` [PATCH v21 11/19] mm/vmscan: remove lruvec reget in move_pages_to_lru Alex Shi
2020-11-05 8:55 ` [PATCH v21 12/19] mm/mlock: remove lru_lock on TestClearPageMlocked Alex Shi
2020-11-11 13:03 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 13/19] mm/mlock: remove __munlock_isolate_lru_page Alex Shi
2020-11-11 13:07 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 14/19] mm/lru: introduce TestClearPageLRU Alex Shi
2020-11-11 13:36 ` Vlastimil Babka
2020-11-12 2:03 ` Hugh Dickins
2020-11-12 11:24 ` Vlastimil Babka [this message]
2020-11-05 8:55 ` [PATCH v21 15/19] mm/compaction: do page isolation first in compaction Alex Shi
2020-11-11 17:12 ` Vlastimil Babka
2020-11-12 2:28 ` Hugh Dickins
2020-11-12 3:35 ` Alex Shi
2020-11-12 11:25 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 16/19] mm/swap.c: serialize memcg changes in pagevec_lru_move_fn Alex Shi
2020-11-11 18:00 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 17/19] mm/lru: replace pgdat lru_lock with lruvec lock Alex Shi
2020-11-05 13:43 ` Alex Shi
2020-11-06 7:48 ` Alex Shi
2020-11-10 18:54 ` Johannes Weiner
2020-11-11 17:46 ` Vlastimil Babka
2020-11-11 17:59 ` Vlastimil Babka
2020-11-12 12:19 ` Vlastimil Babka
2020-11-12 14:19 ` Alex Shi
2020-11-05 8:55 ` [PATCH v21 18/19] mm/lru: introduce the relock_page_lruvec function Alex Shi
2020-11-06 7:50 ` Alex Shi
2020-11-10 18:59 ` Johannes Weiner
2020-11-12 12:31 ` Vlastimil Babka
2020-11-05 8:55 ` [PATCH v21 19/19] mm/lru: revise the comments of lru_lock Alex Shi
2020-11-12 12:37 ` Vlastimil Babka
2020-11-10 12:14 ` [PATCH v21 00/19] per memcg lru lock Alex Shi
2020-11-16 3:45 ` Alex Shi
2020-12-15 0:47 ` Andrew Morton
2020-12-15 2:16 ` Hugh Dickins
2020-12-15 2:28 ` Andrew Morton
2021-01-05 19:30 ` Qian Cai
2021-01-05 19:42 ` Shakeel Butt
2021-01-05 20:11 ` Qian Cai
2021-01-05 21:35 ` Hugh Dickins
2021-01-05 22:01 ` Qian Cai
2021-01-06 3:10 ` Hugh Dickins
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