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X-IronPort-AV: E=McAfee;i="6500,9779,10578"; a="385985863" X-IronPort-AV: E=Sophos;i="5.96,295,1665471600"; d="scan'208";a="385985863" Received: from orsmga003.jf.intel.com ([10.7.209.27]) by orsmga105.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jan 2023 15:30:45 -0800 X-IronPort-AV: E=McAfee;i="6500,9779,10578"; a="604640922" X-IronPort-AV: E=Sophos;i="5.96,295,1665471600"; d="scan'208";a="604640922" Received: from yhuang6-desk2.sh.intel.com (HELO yhuang6-desk2.ccr.corp.intel.com) ([10.238.208.55]) by orsmga003-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 02 Jan 2023 15:30:42 -0800 From: "Huang, Ying" To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Zi Yan , Yang Shi , Baolin Wang , Oscar Salvador , Matthew Wilcox , Bharata B Rao , Alistair Popple , haoxin Subject: Re: [PATCH 5/8] migrate_pages: batch _unmap and _move References: <20221227002859.27740-1-ying.huang@intel.com> <20221227002859.27740-6-ying.huang@intel.com> <20221228152206.52435aef4072c4cad9087541@linux-foundation.org> Date: Tue, 03 Jan 2023 07:29:42 +0800 In-Reply-To: <20221228152206.52435aef4072c4cad9087541@linux-foundation.org> (Andrew Morton's message of "Wed, 28 Dec 2022 15:22:06 -0800") Message-ID: <87edscy0pl.fsf@yhuang6-desk2.ccr.corp.intel.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=ascii X-Rspamd-Queue-Id: B9DF61C001B X-Stat-Signature: eixwowoe4cg513rhjw4dmxj9squ5hnx3 X-Rspam-User: X-Rspamd-Server: rspam08 X-HE-Tag: 1672702250-452575 X-HE-Meta: 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Andrew Morton writes: > On Tue, 27 Dec 2022 08:28:56 +0800 Huang Ying wrote: > >> In this patch the _unmap and _move stage of the folio migration is >> batched. That for, previously, it is, >> >> for each folio >> _unmap() >> _move() >> >> Now, it is, >> >> for each folio >> _unmap() >> for each folio >> _move() >> >> Based on this, we can batch the TLB flushing and use some hardware >> accelerator to copy folios between batched _unmap and batched _move >> stages. >> >> ... >> >> --- a/mm/migrate.c >> +++ b/mm/migrate.c >> @@ -1027,8 +1027,32 @@ static void __migrate_folio_extract(struct folio *dst, >> dst->private = NULL; >> } >> >> +static void migrate_folio_undo_src(struct folio *src, >> + int page_was_mapped, >> + struct anon_vma *anon_vma, >> + struct list_head *ret) >> +{ >> + if (page_was_mapped) >> + remove_migration_ptes(src, src, false); >> + if (anon_vma) >> + put_anon_vma(anon_vma); >> + folio_unlock(src); >> + list_move_tail(&src->lru, ret); >> +} >> + >> +static void migrate_folio_undo_dst(struct folio *dst, >> + free_page_t put_new_page, >> + unsigned long private) >> +{ >> + folio_unlock(dst); >> + if (put_new_page) >> + put_new_page(&dst->page, private); >> + else >> + folio_put(dst); >> +} > > What do the above do? Are they so obvious that no comments are needed? Thank you for reminding, will add comments. > >> static int __migrate_folio_unmap(struct folio *src, struct folio *dst, >> - int force, enum migrate_mode mode) >> + int force, bool force_lock, enum migrate_mode mode) >> { >> int rc = -EAGAIN; >> int page_was_mapped = 0; >> @@ -1055,6 +1079,11 @@ static int __migrate_folio_unmap(struct folio *src, struct folio *dst, >> if (current->flags & PF_MEMALLOC) >> goto out; >> >> + if (!force_lock) { >> + rc = -EDEADLOCK; >> + goto out; >> + } > > Please document the use of EDEADLOCK in this code. What does it signify? Sure. Will do that in the next version. Best Regards, Huang, Ying >> folio_lock(src); >> } >>