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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 7F6E8C4451B for ; Mon, 20 Jul 2026 03:38:17 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 83A6B6B0093; Sun, 19 Jul 2026 23:38:16 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 7C3E36B0095; Sun, 19 Jul 2026 23:38:16 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 68B686B0096; Sun, 19 Jul 2026 23:38:16 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 2BA606B0093 for ; Sun, 19 Jul 2026 23:38:16 -0400 (EDT) Received: from smtpin01.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id B55C31C076C for ; Mon, 20 Jul 2026 03:38:15 +0000 (UTC) X-FDA: 85007746950.01.C123932 Received: from mail-pl1-f173.google.com (mail-pl1-f173.google.com [209.85.214.173]) by imf13.hostedemail.com (Postfix) with ESMTP id ED0A720005 for ; Mon, 20 Jul 2026 03:38:13 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=fPHNRiw7; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf13.hostedemail.com: domain of realwujing@gmail.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=realwujing@gmail.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784518693; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=2IYPYAaWLt0mLcr+u21OpJLddua6jvE6TZ5CKvfA5kU=; b=Loyvt+gdwTL/EkE+8zKYV83AgAZjq9+DDiQqa4PJ6Nqcyruqp+QdyUuDwHzfbsJBOfQe8m hehq8rzQPC9CwtMsYdsedXBauLn5catfTfNdnpKh9LKw4aco+XWtfRIMwh1MsbTATnUCQp 19eXfcRBISZFfgm8+W6ih8vCfjmjyZg= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=gmail.com header.s=20251104 header.b=fPHNRiw7; dmarc=pass (policy=none) header.from=gmail.com; spf=pass (imf13.hostedemail.com: domain of realwujing@gmail.com designates 209.85.214.173 as permitted sender) smtp.mailfrom=realwujing@gmail.com ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784518693; b=RIGLA8n0P9Wtk3L5ottJ6D9k0ErDisAPT6TRUu9SRug9LFq4LN+PruZWZ/imSPvV5z0GBG vqhWP6BriJUciTjSiAHTHAYEMrmF4W/agY4+8Olppb7nMV86cMkZQUkgL7v2Dg3I1vjxYS nPyyJHRcHSCz9EC24ZL1i93k83KEkSM= Received: by mail-pl1-f173.google.com with SMTP id d9443c01a7336-2caed617615so106734055ad.3 for ; Sun, 19 Jul 2026 20:38:13 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1784518693; x=1785123493; darn=kvack.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=2IYPYAaWLt0mLcr+u21OpJLddua6jvE6TZ5CKvfA5kU=; b=fPHNRiw729/FDvNV2PHzAC8StgtvIap6E8PeoLTj63NLn/9wq80CAQGcsEOlLxc7G5 c/BwVL05z1B4J/9gEJl3KsIdyiyXirV7ytVQdRe9MBDdjINtCh0aa6v9CHCfcfEpe0wU QN8EPAnQmdBWej+mDC2WgJN4dPMWpQJuf7pyGVWv+d1KMw/aWWgRyUjKPOJ8DUkJL4FF RqoYd5y5DxdSCtnx3l1CucxE2C9hx6rNWzq0OlD+njm3PvJ4xSWUmotDnCFaOzwCpMen ocyNWpcNOMnA5K1RVH4d3BYq7fJYUB93+2mZuc9vnmXvPZpI6OwNNj4sNQw2OObpJp/j ZYfw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1784518693; x=1785123493; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=2IYPYAaWLt0mLcr+u21OpJLddua6jvE6TZ5CKvfA5kU=; b=ib9Bfa3WR8W1Xd8vm6cpnlfOM5icFkwi/3Z09HOMVR74WInnDvO20y3CCfz5oguF9d EQb5dXAI9sBjhdEY9SfzQHfvhOyxD64sqX6wZOMJ+i7zDNlWxpeqhgxr6s9+EEGyxCRG wOhdzK6fKf0ZCfpXrkNHQwsQ+6GfWAZEfPvjYceBdkgKC9IibnTbERyJ0MShoeHHNpkw DKR6s3LD+JQRqs7cOQXw5R7FkfLj/z/JL2KjMdnhRMksSo30euHc/dL5l5hRlqeGro2T EmPwUDiHkrMGxmsOPYk4N3uIZmqgICHEVfGTf5TQ4YuR+gvVnG5rsJylKrqnSlrbrQiO u36Q== X-Forwarded-Encrypted: i=1; AHgh+RpvDyJ4JA4XNKRGYpoGwzZAzNSpnnNHVupAV8BjKI+6C2oSQteeL07MqaEvk3S2JzIJ4L3Mx2lkjg==@kvack.org X-Gm-Message-State: AOJu0YxR/UYbWEYTI2bfaddjqt7EgRZ52/pZsb2bOAv1Q5c4s5EbKkT8 qiJ5aRCEhFmnH2Np/LJG58eQWWEEFdQhOp2p63xmKUWQTKx8PTFfHSGr X-Gm-Gg: AfdE7cnvkZLAUnv6Nwo5DudHwgIdfrNQOuY/Nzn9Jwv5XRLVdMRAWw5ba5dCVl8iFRI bhmh7PeGvhp8L/01ezNXXzFJCzfgMXM0UCJtTm5+qDkojHazyw0qyA1lBdw0pice6ewkRxCcXCC gfVHzz3Re5njQ8He/jWthB+wQibED98PFhjXYL2A63vCTMlBwkxjXkX/V0mPc7xmzBKJXMbl8d2 CknYoIS/bml7Xi1bbCjd4uB7KRtZnSWLP549d5VQYtBW/GujixqbXY8bFkogf3Q/mGm7SxDPfpK P2tlsBOS82wZCdE0yc4DJxPqYHc9vUSzm41yLSm5tcABH3nCfapMc7/ZpMG3ComWLSvreHMUxKS flt9ldbWwiYviSHvq5CSovKH/f0j0U9L9SyvQEJZapBb8ov9QEhSDMjyPLq+dgMWqL9qk7RA= X-Received: by 2002:a05:6a20:2583:b0:3c0:ac0f:6558 with SMTP id adf61e73a8af0-3c3ad677d0amr13026984637.2.1784518692673; Sun, 19 Jul 2026 20:38:12 -0700 (PDT) Received: from ubuntu.. ([23.254.208.9]) by smtp.gmail.com with ESMTPSA id a92af1059eb24-13ce2ddfb35sm26535048c88.14.2026.07.19.20.38.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 19 Jul 2026 20:38:12 -0700 (PDT) From: Jing Wu To: Vlastimil Babka Cc: Qiliang Yuan , Andrew Morton , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Axel Rasmussen , Yuanchu Xie , Wei Xu , Brendan Jackman , Johannes Weiner , Zi Yan , Lance Yang , SeongJae Park , Matthew Wilcox , linux-mm@kvack.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org Subject: Re: [PATCH v10] mm/page_alloc: boost watermarks on atomic allocation failure Date: Mon, 20 Jul 2026 11:38:03 +0800 Message-ID: <20260720033804.3862547-1-realwujing@gmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: References: <20260214-wujing-mm-page_alloc-v8-v10-1-bdfea431fd97@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Stat-Signature: jyq1rmwo7b7e5uschxunycyseor9ypr3 X-Rspamd-Queue-Id: ED0A720005 X-Rspamd-Server: rspam01 X-Rspam-User: X-HE-Tag: 1784518693-483630 X-HE-Meta: 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 gAaFAstw 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Qiliang Yuan Hi Vlastimil, Thanks for the review, and understood on taking the Ack back - the v10 changes were substantial, and I won't send v11 just to drop the tag. I'm folding it into an actual update instead. Let me answer your three points directly. 1) The Ack Yours is dropped. I've kept SeongJae's for now since he hasn't said anything to the contrary, but I'll understand if he'd rather it not carry over either, given v11 also fixes a debounce race in the atomic path that nobody, including me, had caught in nine prior rounds: last_boost_jiffies was checked and updated outside zone->lock, so concurrent CPUs (e.g. a multi-queue NIC spreading GFP_ATOMIC allocations across several softirqs) could all pass the once-per-second check for the same zone before either updated the timestamp. 2) Real-world benefit and side effects I don't have a clean before/after deployment number for this exact patch yet, and I want to be upfront about that. What I do have: a production host running a downstream 4.19 kernel logged 144 order-0 GFP_ATOMIC failures over a 4h15m window, every single one through the same NIC driver RX softirq path (bnxt_rx_pages -> net_rx_action -> __alloc_pages_slowpath), across several unrelated network-facing services on the box. That's evidence the failure mode is real and ongoing - it is not evidence that this patch fixes it, and I don't want to conflate the two. On side effects: the mechanism is bounded by construction, not just by intent. Each zone accepts at most one boost per second (the debounce timer), and watermark_boost is clamped to _watermark[WMARK_HIGH] / 10 per zone, independent of how many zones get boosted in a single slowpath call. Worst case this adds one extra kswapd wakeup per zone per second, and the ceiling on any single zone is 10% of its own high watermark - it can't run away or starve unrelated allocations past that. I've put this bound into the commit message itself so it isn't only visible in this thread. I know a bound isn't a measurement. If it would actually help, I can try to build a synthetic reproducer (fault-injected GFP_ATOMIC pressure under load) and come back with before/after numbers instead of leaving this as theory - let me know if that's the kind of evidence that would move this forward for you. 3) netdev Cc'd this time, along with Matthew Wilcox, who asked for the same thing on v1 and was never followed up on. Sorry that took ten versions. Thanks for staying on this thread. Qiliang