[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <026aaebd-ceb3-0659-8f54-2ec3cd81b5df@linux.alibaba.com>
Date: Wed, 2 Aug 2023 19:20:24 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Kemeng Shi <shikemeng@...weicloud.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
mgorman@...hsingularity.net, david@...hat.com
Subject: Re: [PATCH v2 2/8] mm/compaction: correct last_migrated_pfn update in
compact_zone
On 8/2/2023 5:37 PM, Kemeng Shi wrote:
> We record start pfn of last isolated page block with last_migrated_pfn. And
> then:
> 1. We check if we mark the page block skip for exclusive access in
> isolate_migratepages_block by test if next migrate pfn is still in last
> isolated page block. If so, we will set finish_pageblock to do the rescan.
> 2. We check if a full cc->order block is scanned by test if last scan range
> passes the cc->order block boundary. If so, we flush the pages were freed.
>
> We treat cc->migrate_pfn before isolate_migratepages as the start pfn of
> last isolated page range. However, we always align migrate_pfn to page block
> or move to another page block in fast_find_migrateblock or in linearly scan
> forward in isolate_migratepages before do page isolation in
> isolate_migratepages_block.
>
> Update last_migrated_pfn with pageblock_start_pfn(cc->migrate_pfn - 1)
> after scan to correctly set start pfn of last isolated page range. To
> avoid that:
> 1. Miss a rescan with finish_pageblock set as last_migrate_pfn does not
> point to right pageblock and the migrate will not be in pageblock of
> last_migrate_pfn as it should be.
> 2. Wrongly issue flush by test cc->order block boundary with wrong
> last_migrate_pfn.
>
> Signed-off-by: Kemeng Shi <shikemeng@...weicloud.com>
LGTM.
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>
> ---
> mm/compaction.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/mm/compaction.c b/mm/compaction.c
> index a8cea916df9d..ec3a96b7afce 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -2487,7 +2487,8 @@ compact_zone(struct compact_control *cc, struct capture_control *capc)
> goto check_drain;
> case ISOLATE_SUCCESS:
> update_cached = false;
> - last_migrated_pfn = iteration_start_pfn;
> + last_migrated_pfn = max(cc->zone->zone_start_pfn,
> + pageblock_start_pfn(cc->migrate_pfn - 1));
> }
>
> err = migrate_pages(&cc->migratepages, compaction_alloc,
Powered by blists - more mailing lists