From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE310C433FE for ; Tue, 22 Nov 2022 22:40:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235164AbiKVWk2 (ORCPT ); Tue, 22 Nov 2022 17:40:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43272 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233207AbiKVWk0 (ORCPT ); Tue, 22 Nov 2022 17:40:26 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A8F94C78C5 for ; Tue, 22 Nov 2022 14:40:25 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 603C8B81DEC for ; Tue, 22 Nov 2022 22:40:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DDCE6C433D6; Tue, 22 Nov 2022 22:40:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1669156823; bh=D12225qDBaGNNZ3gC0JwBIPyCKem+YlMkKRiMYyJ9Pg=; h=Date:To:From:Subject:From; b=EYA05cK0h9wK9jB7S9pMbK+LI9n3IKXZsLnXs7Nq9QZyvirELavgffKZE0saBOG2b H32SsPBaM6Fed9Dhhg24FgUk0gvuuYzwET6F36qsBsIO0mYU90e35CShdo/JCdgjx1 QjAY6XBedWFyRvqln+Ia9cRFtNBAPwTnf0WLpxCs= Date: Tue, 22 Nov 2022 14:40:22 -0800 To: mm-commits@vger.kernel.org, vbabka@suse.cz, mgorman@techsingularity.net, akpm@linux-foundation.org From: Andrew Morton Subject: + mm-page_alloc-simplify-locking-during-free_unref_page_list.patch added to mm-unstable branch Message-Id: <20221122224022.DDCE6C433D6@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: mm/page_alloc: simplify locking during free_unref_page_list has been added to the -mm mm-unstable branch. Its filename is mm-page_alloc-simplify-locking-during-free_unref_page_list.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-page_alloc-simplify-locking-during-free_unref_page_list.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 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 via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Mel Gorman Subject: mm/page_alloc: simplify locking during free_unref_page_list Date: Tue, 22 Nov 2022 13:12:29 +0000 While freeing a large list, the zone lock will be released and reacquired to avoid long hold times since commit c24ad77d962c ("mm/page_alloc.c: avoid excessive IRQ disabled times in free_unref_page_list()"). As suggested by Vlastimil Babka, the lockrelease/reacquire logic can be simplified by reusing the logic that acquires a different lock when changing zones. Link: https://lkml.kernel.org/r/20221122131229.5263-3-mgorman@techsingularity.net Signed-off-by: Mel Gorman Reviewed-by: Vlastimil Babka Signed-off-by: Andrew Morton --- mm/page_alloc.c | 25 +++++++++---------------- 1 file changed, 9 insertions(+), 16 deletions(-) --- a/mm/page_alloc.c~mm-page_alloc-simplify-locking-during-free_unref_page_list +++ a/mm/page_alloc.c @@ -3540,13 +3540,19 @@ void free_unref_page_list(struct list_he list_del(&page->lru); migratetype = get_pcppage_migratetype(page); - /* Different zone, different pcp lock. */ - if (zone != locked_zone) { + /* + * Either different zone requiring a different pcp lock or + * excessive lock hold times when freeing a large list of + * pages. + */ + if (zone != locked_zone || batch_count == SWAP_CLUSTER_MAX) { if (pcp) { pcp_spin_unlock(pcp); pcp_trylock_finish(UP_flags); } + batch_count = 0; + /* * trylock is necessary as pages may be getting freed * from IRQ or SoftIRQ context after an IO completion. @@ -3561,7 +3567,6 @@ void free_unref_page_list(struct list_he continue; } locked_zone = zone; - batch_count = 0; } /* @@ -3573,19 +3578,7 @@ void free_unref_page_list(struct list_he trace_mm_page_free_batched(page); free_unref_page_commit(zone, pcp, page, migratetype, 0); - - /* - * Guard against excessive lock hold times when freeing - * a large list of pages. Lock will be reacquired if - * necessary on the next iteration. - */ - if (++batch_count == SWAP_CLUSTER_MAX) { - pcp_spin_unlock(pcp); - pcp_trylock_finish(UP_flags); - batch_count = 0; - pcp = NULL; - locked_zone = NULL; - } + batch_count++; } if (pcp) { _ Patches currently in -mm which might be from mgorman@techsingularity.net are mm-page_alloc-always-remove-pages-from-temporary-list.patch mm-page_alloc-leave-irqs-enabled-for-per-cpu-page-allocations.patch mm-page_alloc-leave-irqs-enabled-for-per-cpu-page-allocations-fix.patch mm-page_alloc-simplify-locking-during-free_unref_page_list.patch