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 33231C4332F for ; Thu, 9 Nov 2023 17:49:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344847AbjKIRuA (ORCPT ); Thu, 9 Nov 2023 12:50:00 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52760 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231845AbjKIRt5 (ORCPT ); Thu, 9 Nov 2023 12:49:57 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6530A269E for ; Thu, 9 Nov 2023 09:49:55 -0800 (PST) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF245C433C8; Thu, 9 Nov 2023 17:49:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1699552195; bh=lZIcEOpqBq7V6sLEF4bOlqA/HFLe7+H0GXK/xFyC9AM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=xYTL38kU6Vve0VHhIA7PDkbEO6ODJS5kTg/g66xnrnAWnQ6fv2bvOLu68oKa36UG3 kLTKkhys5fV65SoLxC7MKrTU2QsIxGKzV79mqNn2AYrcCPWF4lVjNe1UQB08xSBqJb hTFFSzDJwriZyA8r19DYDpNEpgRb9FlJYZY9q4sM= Date: Thu, 9 Nov 2023 09:49:54 -0800 From: Andrew Morton To: Zhiguo Jiang Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Johannes Weiner , opensource.kernel@vivo.com Subject: Re: [PATCH v2 1/1] mm: ALLOC_HIGHATOMIC flag allocation issue Message-Id: <20231109094954.dd4b2a5b1f5dfcc9a721edba@linux-foundation.org> In-Reply-To: <20231109073133.792-2-justinjiang@vivo.com> References: <20231109073133.792-1-justinjiang@vivo.com> <20231109073133.792-2-justinjiang@vivo.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 9 Nov 2023 15:31:33 +0800 Zhiguo Jiang wrote: > Add a new bool* argument to pass return flag instead of *alloc_flags > and add the related comments. Please retain (and update) the changelog with each version of a patch. For reviewers (please), here's the v1 changelog: : In case of alloc_flags contain ALLOC_HIGHATOMIC and alloc order : is order1/2/3/10 in rmqueue(), if pages are alloced successfully : from pcplist cache, and move a free pageblock from the alloced : migratetype freelist to MIGRATE_HIGHATOMIC freelist, rather than : alloc from MIGRATE_HIGHATOMIC freelist firstly, so this will result : in an increasing number of pages on the MIGRATE_HIGHATOMIC freelist, : pages in other migratetype freelist are reduced and more likely to : allocation failure. : : Currently the sequence of ALLOC_HIGHATOMIC allocation is: : pcplist cache --> buddy (batch >> order) allocation migratetype : freelist --> buddy MIGRATE_HIGHATOMIC freelist --> buddy allocation : migratetype freelist. : : Due to the fact that requesting pages from the pcplist cache is faster : than buddy, the sequence of modifying the ALLOC_HIGHATOMIC allocation is: : pcplist --> buddy MIGRATE_HIGHATOMIC freelist --> buddy allocation : migrate freelist. : : This patch can solve the allocation failure of the Non-ALLOC_HIGHATOMIC : alloc_flag due to excessive pages reservations in MIGRATE_HIGHATOMIC : freelists. > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -905,7 +905,6 @@ unsigned int reclaim_clean_pages_from_list(struct zone *zone, > #endif > #define ALLOC_HIGHATOMIC 0x200 /* Allows access to MIGRATE_HIGHATOMIC */ > #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAIM set */ > -#define ALLOC_PCPLIST 0x1000 /* Allocations from pcplist */ > > /* Flags that allow allocations below the min watermark. */ > #define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|ALLOC_OOM) > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 67cec88164b1..3c84c3e3eeb0 100755 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -2854,6 +2854,11 @@ struct page *__rmqueue_pcplist(struct zone *zone, unsigned int order, > int batch = nr_pcp_alloc(pcp, zone, order); > int alloced; > > + /* > + * If pcplist is empty and alloc_flags is with ALLOC_HIGHATOMIC, > + * it should alloc from buddy highatomic migrate freelist firstly > + * to ensure quick and successful allocation. > + */ > if (alloc_flags & ALLOC_HIGHATOMIC) > goto out; > > @@ -2925,8 +2930,8 @@ __no_sanitize_memory > static inline > struct page *rmqueue(struct zone *preferred_zone, > struct zone *zone, unsigned int order, > - gfp_t gfp_flags, unsigned int *alloc_flags, > - int migratetype) > + gfp_t gfp_flags, unsigned int alloc_flags, > + int migratetype, bool *highatomc_allocation) > { > struct page *page; > > @@ -2938,19 +2943,33 @@ struct page *rmqueue(struct zone *preferred_zone, > > if (likely(pcp_allowed_order(order))) { > page = rmqueue_pcplist(preferred_zone, zone, order, > - migratetype, *alloc_flags); > - if (likely(page)) { > - *alloc_flags |= ALLOC_PCPLIST; > + migratetype, alloc_flags); > + if (likely(page)) > goto out; > - } > } > > - page = rmqueue_buddy(preferred_zone, zone, order, *alloc_flags, > + page = rmqueue_buddy(preferred_zone, zone, order, alloc_flags, > migratetype); > > + /* > + * The high-order atomic allocation pageblock reserved conditions: > + * > + * If the high-order atomic allocation page is alloced from pcplist, > + * the highatomic pageblock does not need to be reserved, which can > + * void to migrate an increasing number of pages into buddy > + * MIGRATE_HIGHATOMIC freelist and lead to an increasing risk of > + * allocation failure on other buddy migrate freelists. > + * > + * If the high-order atomic allocation page is alloced from buddy > + * highatomic migrate freelist, regardless of whether the allocation > + * is successful or not, the highatomic pageblock can try to be > + * reserved. > + */ > + if (unlikely(alloc_flags & ALLOC_HIGHATOMIC)) > + *highatomc_allocation = true; > out: > /* Separate test+clear to avoid unnecessary atomics */ > - if ((*alloc_flags & ALLOC_KSWAPD) && > + if ((alloc_flags & ALLOC_KSWAPD) && > unlikely(test_bit(ZONE_BOOSTED_WATERMARK, &zone->flags))) { > clear_bit(ZONE_BOOSTED_WATERMARK, &zone->flags); > wakeup_kswapd(zone, 0, 0, zone_idx(zone)); > @@ -3218,6 +3237,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > struct pglist_data *last_pgdat = NULL; > bool last_pgdat_dirty_ok = false; > bool no_fallback; > + bool highatomc_allocation = false; > > retry: > /* > @@ -3349,7 +3369,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > > try_this_zone: > page = rmqueue(ac->preferred_zoneref->zone, zone, order, > - gfp_mask, &alloc_flags, ac->migratetype); > + gfp_mask, alloc_flags, ac->migratetype, &highatomc_allocation); > if (page) { > prep_new_page(page, order, gfp_mask, alloc_flags); > > @@ -3357,8 +3377,7 @@ get_page_from_freelist(gfp_t gfp_mask, unsigned int order, int alloc_flags, > * If this is a high-order atomic allocation then check > * if the pageblock should be reserved for the future > */ > - if (unlikely(alloc_flags & ALLOC_HIGHATOMIC) && > - unlikely(!(alloc_flags & ALLOC_PCPLIST))) > + if (unlikely(highatomc_allocation)) > reserve_highatomic_pageblock(page, zone); > > return page; > -- > 2.39.0