From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: + mm-migratec-migrate-pg_readahead-flag.patch added to -mm tree Date: Thu, 13 Feb 2020 18:57:02 -0800 Message-ID: <20200214025702.eluMnK_Zb%akpm@linux-foundation.org> References: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Return-path: Received: from mail.kernel.org ([198.145.29.99]:37602 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727604AbgBNC5D (ORCPT ); Thu, 13 Feb 2020 21:57:03 -0500 In-Reply-To: <20200203173311.6269a8be06a05e5a4aa08a93@linux-foundation.org> Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: mgorman@techsingularity.net, mhocko@suse.com, mm-commits@vger.kernel.org, willy@infradead.org, yang.shi@linux.alibaba.com The patch titled Subject: mm/migrate.c: migrate PG_readahead flag has been added to the -mm tree. Its filename is mm-migratec-migrate-pg_readahead-flag.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-migratec-migrate-pg_readahead-flag.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-migratec-migrate-pg_readahead-flag.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Yang Shi Subject: mm/migrate.c: migrate PG_readahead flag Currently the migration code doesn't migrate PG_readahead flag. Theoretically this would incur slight performance loss as the application might have to ramp its readahead back up again. Even though such problem happens, it might be hidden by something else since migration is typically triggered by compaction and NUMA balancing, any of which should be more noticeable. Migrate the flag after end_page_writeback() since it may clear PG_reclaim flag, which is the same bit as PG_readahead, for the new page. Link: http://lkml.kernel.org/r/1581640185-95731-1-git-send-email-yang.shi@linux.alibaba.com Signed-off-by: Yang Shi Cc: Matthew Wilcox Cc: Michal Hocko Cc: Mel Gorman Signed-off-by: Andrew Morton --- mm/migrate.c | 8 ++++++++ 1 file changed, 8 insertions(+) --- a/mm/migrate.c~mm-migratec-migrate-pg_readahead-flag +++ a/mm/migrate.c @@ -647,6 +647,14 @@ void migrate_page_states(struct page *ne if (PageWriteback(newpage)) end_page_writeback(newpage); + /* + * PG_readahead share the same bit with PG_reclaim, the above + * end_page_writeback() may clear PG_readahead mistakenly, so set + * the bit after that. + */ + if (PageReadahead(page)) + SetPageReadahead(newpage); + copy_page_owner(page, newpage); mem_cgroup_migrate(page, newpage); _ Patches currently in -mm which might be from yang.shi@linux.alibaba.com are mm-vmpressure-dont-need-call-kfree-if-kstrndup-fails.patch mm-vmpressure-use-mem_cgroup_is_root-api.patch mm-migratec-migrate-pg_readahead-flag.patch