From: Matthew Wilcox <willy@infradead.org>
To: Minchan Kim <minchan@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
LKML <linux-kernel@vger.kernel.org>,
cgoldswo@codeaurora.org, linux-fsdevel@vger.kernel.org,
mhocko@suse.com, david@redhat.com, vbabka@suse.cz,
viro@zeniv.linux.org.uk, joaodias@google.com
Subject: Re: [RFC 1/2] mm: disable LRU pagevec during the migration temporarily
Date: Tue, 16 Feb 2021 18:22:42 +0000 [thread overview]
Message-ID: <20210216182242.GJ2858050@casper.infradead.org> (raw)
In-Reply-To: <20210216170348.1513483-1-minchan@kernel.org>
On Tue, Feb 16, 2021 at 09:03:47AM -0800, Minchan Kim wrote:
> LRU pagevec holds refcount of pages until the pagevec are drained.
> It could prevent migration since the refcount of the page is greater
> than the expection in migration logic. To mitigate the issue,
> callers of migrate_pages drains LRU pagevec via migrate_prep or
> lru_add_drain_all before migrate_pages call.
>
> However, it's not enough because pages coming into pagevec after the
> draining call still could stay at the pagevec so it could keep
> preventing page migration. Since some callers of migrate_pages have
> retrial logic with LRU draining, the page would migrate at next trail
> but it is still fragile in that it doesn't close the fundamental race
> between upcoming LRU pages into pagvec and migration so the migration
> failure could cause contiguous memory allocation failure in the end.
Have you been able to gather any numbers on this? eg does migration
now succeed 5% more often?
next prev parent reply other threads:[~2021-02-16 18:24 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-16 17:03 [RFC 1/2] mm: disable LRU pagevec during the migration temporarily Minchan Kim
2021-02-16 17:03 ` [RFC 2/2] mm: fs: Invalidate BH LRU during page migration Minchan Kim
2021-02-16 18:22 ` Matthew Wilcox [this message]
2021-02-16 21:30 ` [RFC 1/2] mm: disable LRU pagevec during the migration temporarily Minchan Kim
2021-02-17 8:59 ` Michal Hocko
2021-02-17 9:50 ` Michal Hocko
2021-02-17 20:51 ` Minchan Kim
2021-02-17 21:11 ` Matthew Wilcox
2021-02-17 21:22 ` Minchan Kim
2021-02-17 20:46 ` Minchan Kim
2021-02-17 21:16 ` Matthew Wilcox
2021-02-17 21:32 ` Minchan Kim
2021-02-18 8:17 ` Michal Hocko
2021-02-18 8:24 ` David Hildenbrand
2021-02-18 15:52 ` Minchan Kim
2021-02-18 16:08 ` Michal Hocko
2021-02-18 16:21 ` Minchan Kim
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