From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 59F297DA7F; Wed, 6 Nov 2024 12:32:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730896361; cv=none; b=PiaMmS2w/dR4D2TdYMjiez25fIukAnkUAZCdL42i+hE2EETsL45EAa1C7UZUhGFvsfZLEnw8VLaVlwNdzoPrn+U/UL4vHkpe5SLY+9O/ADNMeSdwMid84ks7obxBlqhynvE+hyT0fnlf/XBRFOCk83yL8qOygmHTBv0MGl7XoZQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730896361; c=relaxed/simple; bh=g9gw8P4YtUt6Jb3hUfIw7pqS0hzCblkIAuiTOZdRdaU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RpqogDLiX35URKFvR1jajrbb4YMozKCKJJCuECWdlJMzjgxzqB7qiePzbY4QFdI61mWCPZAh9ArU84lblhluqJ6yiir6oIfpis23sCb1ogKTtFrq+6iqgCwP60ddrw/8KzShPuc3lWEy9dfrLWUf+kvgUvoODDlOfDu04SfDRYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=O4nX0k38; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="O4nX0k38" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D2545C4CECD; Wed, 6 Nov 2024 12:32:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1730896361; bh=g9gw8P4YtUt6Jb3hUfIw7pqS0hzCblkIAuiTOZdRdaU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=O4nX0k38N4Vha/41tulTjpR1COUeyps27nQhvQKiMtrckU+ThA0HcAMfXIN9Mi1QU TaBxkqQxoNBY7UB+ACqncxV6jVbuiH8QQ0IdIjebEJvffqZg9dFxNJ6NjpYsBdS+Pw U5bbbqYOPkGZABg3l0l1WY2NFaIeHXv6u1XTRuoc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Matt Fleming , Vlastimil Babka , Mel Gorman , Michal Hocko , Andrew Morton , Sasha Levin Subject: [PATCH 6.11 176/245] mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves Date: Wed, 6 Nov 2024 13:03:49 +0100 Message-ID: <20241106120323.570324244@linuxfoundation.org> X-Mailer: git-send-email 2.47.0 In-Reply-To: <20241106120319.234238499@linuxfoundation.org> References: <20241106120319.234238499@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.11-stable review patch. If anyone has any objections, please let me know. ------------------ From: Matt Fleming [ Upstream commit 281dd25c1a018261a04d1b8bf41a0674000bfe38 ] Under memory pressure it's possible for GFP_ATOMIC order-0 allocations to fail even though free pages are available in the highatomic reserves. GFP_ATOMIC allocations cannot trigger unreserve_highatomic_pageblock() since it's only run from reclaim. Given that such allocations will pass the watermarks in __zone_watermark_unusable_free(), it makes sense to fallback to highatomic reserves the same way that ALLOC_OOM can. This fixes order-0 page allocation failures observed on Cloudflare's fleet when handling network packets: kswapd1: page allocation failure: order:0, mode:0x820(GFP_ATOMIC), nodemask=(null),cpuset=/,mems_allowed=0-7 CPU: 10 PID: 696 Comm: kswapd1 Kdump: loaded Tainted: G O 6.6.43-CUSTOM #1 Hardware name: MACHINE Call Trace: dump_stack_lvl+0x3c/0x50 warn_alloc+0x13a/0x1c0 __alloc_pages_slowpath.constprop.0+0xc9d/0xd10 __alloc_pages+0x327/0x340 __napi_alloc_skb+0x16d/0x1f0 bnxt_rx_page_skb+0x96/0x1b0 [bnxt_en] bnxt_rx_pkt+0x201/0x15e0 [bnxt_en] __bnxt_poll_work+0x156/0x2b0 [bnxt_en] bnxt_poll+0xd9/0x1c0 [bnxt_en] __napi_poll+0x2b/0x1b0 bpf_trampoline_6442524138+0x7d/0x1000 __napi_poll+0x5/0x1b0 net_rx_action+0x342/0x740 handle_softirqs+0xcf/0x2b0 irq_exit_rcu+0x6c/0x90 sysvec_apic_timer_interrupt+0x72/0x90 [mfleming@cloudflare.com: update comment] Link: https://lkml.kernel.org/r/20241015125158.3597702-1-matt@readmodwrite.com Link: https://lkml.kernel.org/r/20241011120737.3300370-1-matt@readmodwrite.com Link: https://lore.kernel.org/all/CAGis_TWzSu=P7QJmjD58WWiu3zjMTVKSzdOwWE8ORaGytzWJwQ@mail.gmail.com/ Fixes: 1d91df85f399 ("mm/page_alloc: handle a missing case for memalloc_nocma_{save/restore} APIs") Signed-off-by: Matt Fleming Suggested-by: Vlastimil Babka Reviewed-by: Vlastimil Babka Cc: Mel Gorman Cc: Michal Hocko Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin --- mm/page_alloc.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 91ace8ca97e21..ec459522c2934 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -2874,12 +2874,12 @@ struct page *rmqueue_buddy(struct zone *preferred_zone, struct zone *zone, page = __rmqueue(zone, order, migratetype, alloc_flags); /* - * If the allocation fails, allow OOM handling access - * to HIGHATOMIC reserves as failing now is worse than - * failing a high-order atomic allocation in the - * future. + * If the allocation fails, allow OOM handling and + * order-0 (atomic) allocs access to HIGHATOMIC + * reserves as failing now is worse than failing a + * high-order atomic allocation in the future. */ - if (!page && (alloc_flags & ALLOC_OOM)) + if (!page && (alloc_flags & (ALLOC_OOM|ALLOC_NON_BLOCK))) page = __rmqueue_smallest(zone, order, MIGRATE_HIGHATOMIC); if (!page) { -- 2.43.0