From nobody Tue Sep 16 00:50:13 2025 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 141ACC6379F for ; Mon, 9 Jan 2023 15:19:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233892AbjAIPSR (ORCPT ); Mon, 9 Jan 2023 10:18:17 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33288 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237211AbjAIPR5 (ORCPT ); Mon, 9 Jan 2023 10:17:57 -0500 Received: from outbound-smtp47.blacknight.com (outbound-smtp47.blacknight.com [46.22.136.64]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 4A04955A1 for ; Mon, 9 Jan 2023 07:17:47 -0800 (PST) Received: from mail.blacknight.com (pemlinmail04.blacknight.ie [81.17.254.17]) by outbound-smtp47.blacknight.com (Postfix) with ESMTPS id D1B80FA8A7 for ; Mon, 9 Jan 2023 15:17:45 +0000 (GMT) Received: (qmail 19193 invoked from network); 9 Jan 2023 15:17:45 -0000 Received: from unknown (HELO morpheus.112glenside.lan) (mgorman@techsingularity.net@[84.203.198.246]) by 81.17.254.9 with ESMTPA; 9 Jan 2023 15:17:45 -0000 From: Mel Gorman To: Linux-MM Cc: Andrew Morton , Michal Hocko , NeilBrown , Thierry Reding , Matthew Wilcox , Vlastimil Babka , LKML , Mel Gorman Subject: [PATCH 6/7] mm/page_alloc: Give GFP_ATOMIC and non-blocking allocations access to reserves Date: Mon, 9 Jan 2023 15:16:30 +0000 Message-Id: <20230109151631.24923-7-mgorman@techsingularity.net> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20230109151631.24923-1-mgorman@techsingularity.net> References: <20230109151631.24923-1-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" Explicit GFP_ATOMIC allocations get flagged ALLOC_HARDER which is a bit vague. In preparation for removing __GFP_ATOMIC, give GFP_ATOMIC and other non-blocking allocation requests equal access to reserve. Rename ALLOC_HARDER to ALLOC_NON_BLOCK to make it more clear what the flag means. Signed-off-by: Mel Gorman Acked-by: Vlastimil Babka --- mm/internal.h | 7 +++++-- mm/page_alloc.c | 23 +++++++++++++---------- 2 files changed, 18 insertions(+), 12 deletions(-) diff --git a/mm/internal.h b/mm/internal.h index 8706d46863df..23a37588073a 100644 --- a/mm/internal.h +++ b/mm/internal.h @@ -735,7 +735,10 @@ unsigned int reclaim_clean_pages_from_list(struct zone= *zone, #define ALLOC_OOM ALLOC_NO_WATERMARKS #endif =20 -#define ALLOC_HARDER 0x10 /* try to alloc harder */ +#define ALLOC_NON_BLOCK 0x10 /* Caller cannot block. Allow access + * to 25% of the min watermark or + * 62.5% if __GFP_HIGH is set. + */ #define ALLOC_MIN_RESERVE 0x20 /* __GFP_HIGH set. Allow access to 50% * of the min watermark. */ @@ -750,7 +753,7 @@ unsigned int reclaim_clean_pages_from_list(struct zone = *zone, #define ALLOC_KSWAPD 0x800 /* allow waking of kswapd, __GFP_KSWAPD_RECLAI= M set */ =20 /* Flags that allow allocations below the min watermark. */ -#define ALLOC_RESERVES (ALLOC_HARDER|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC|AL= LOC_OOM) +#define ALLOC_RESERVES (ALLOC_NON_BLOCK|ALLOC_MIN_RESERVE|ALLOC_HIGHATOMIC= |ALLOC_OOM) =20 enum ttu_flags; struct tlbflush_unmap_batch; diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d2df78f5baa2..2217bab2dbb2 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3999,7 +3999,7 @@ bool __zone_watermark_ok(struct zone *z, unsigned int= order, unsigned long mark, * if it cannot get memory quickly, particularly if it's * also __GFP_HIGH. */ - if (alloc_flags & ALLOC_HARDER) + if (alloc_flags & ALLOC_NON_BLOCK) min -=3D min / 4; =20 /* @@ -4851,28 +4851,30 @@ gfp_to_alloc_flags(gfp_t gfp_mask, unsigned int ord= er) * The caller may dip into page reserves a bit more if the caller * cannot run direct reclaim, or if the caller has realtime scheduling * policy or is asking for __GFP_HIGH memory. GFP_ATOMIC requests will - * set both ALLOC_HARDER (__GFP_ATOMIC) and ALLOC_MIN_RESERVE(__GFP_HIGH). + * set both ALLOC_NON_BLOCK and ALLOC_MIN_RESERVE(__GFP_HIGH). */ alloc_flags |=3D (__force int) (gfp_mask & (__GFP_HIGH | __GFP_KSWAPD_RECLAIM)); =20 - if (gfp_mask & __GFP_ATOMIC) { + if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) { /* * Not worth trying to allocate harder for __GFP_NOMEMALLOC even * if it can't schedule. */ if (!(gfp_mask & __GFP_NOMEMALLOC)) { - alloc_flags |=3D ALLOC_HARDER; + alloc_flags |=3D ALLOC_NON_BLOCK; =20 if (order > 0) alloc_flags |=3D ALLOC_HIGHATOMIC; } =20 /* - * Ignore cpuset mems for GFP_ATOMIC rather than fail, see the - * comment for __cpuset_node_allowed(). + * Ignore cpuset mems for non-blocking __GFP_HIGH (probably + * GFP_ATOMIC) rather than fail, see the comment for + * __cpuset_node_allowed(). */ - alloc_flags &=3D ~ALLOC_CPUSET; + if (alloc_flags & ALLOC_MIN_RESERVE) + alloc_flags &=3D ~ALLOC_CPUSET; } else if (unlikely(rt_task(current)) && in_task()) alloc_flags |=3D ALLOC_MIN_RESERVE; =20 @@ -5304,11 +5306,12 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int= order, =20 /* * Help non-failing allocations by giving them access to memory - * reserves but do not use ALLOC_NO_WATERMARKS because this + * reserves normally used for high priority non-blocking + * allocations but do not use ALLOC_NO_WATERMARKS because this * could deplete whole memory reserves which would just make - * the situation worse + * the situation worse. */ - page =3D __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERV= E|ALLOC_HARDER, ac); + page =3D __alloc_pages_cpuset_fallback(gfp_mask, order, ALLOC_MIN_RESERV= E|ALLOC_NON_BLOCK, ac); if (page) goto got_pg; =20 --=20 2.35.3