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 8099D10F92E0 for ; Tue, 31 Mar 2026 16:44:36 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id E71096B0095; Tue, 31 Mar 2026 12:44:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E48826B0096; Tue, 31 Mar 2026 12:44:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D5E5B6B0098; Tue, 31 Mar 2026 12:44:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id C458D6B0095 for ; Tue, 31 Mar 2026 12:44:35 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 7B2ED1B6E98 for ; Tue, 31 Mar 2026 16:44:35 +0000 (UTC) X-FDA: 84606931710.09.2834B71 Received: from mail-pl1-f181.google.com (mail-pl1-f181.google.com [209.85.214.181]) by imf12.hostedemail.com (Postfix) with ESMTP id A9DF240009 for ; Tue, 31 Mar 2026 16:44:33 +0000 (UTC) Authentication-Results: imf12.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b=XQIfmewb; spf=pass (imf12.hostedemail.com: domain of rientjes@google.com designates 209.85.214.181 as permitted sender) smtp.mailfrom=rientjes@google.com; dmarc=pass (policy=reject) header.from=google.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1774975473; a=rsa-sha256; cv=none; b=4WE/irwnLcciZJXuqpqTtmG5qWHGQdU7YGrv+UogDmpnkOTpjzcoMKZrukc7NshH2RpuEC UKYTNnnPQGn/0u2OQpZBp/OKYZh/8Vn85AbPjtsDXgkgBHUNkpPOvLEU8DreEZNP+m6CvR scnfx7A7zsrl78wG5HJjFRtRqWNdo+w= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1774975473; 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-type:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=P9H7DtjUvqhXDyY5pBkhMdsDwbb7SsdQitFkTuKYIC0=; b=17i/4cpoBawNyWBbEeh1uTpm9sTc+PqTymLsARtdKjtyE7enV0xoeZbq2NZ4B02US6vQHD r6XGYxWD9rMapeZ/1NSprgweF7bpErFJOXjy2hZBzsVaI2xnPnrl2s9yBJG+tkvEgizwa2 1s+We1fh1OckKCBRMjq6PP7Xs+B8+nI= ARC-Authentication-Results: i=1; imf12.hostedemail.com; dkim=pass header.d=google.com header.s=20251104 header.b=XQIfmewb; spf=pass (imf12.hostedemail.com: domain of rientjes@google.com designates 209.85.214.181 as permitted sender) smtp.mailfrom=rientjes@google.com; dmarc=pass (policy=reject) header.from=google.com Received: by mail-pl1-f181.google.com with SMTP id d9443c01a7336-2b243198058so94665ad.1 for ; Tue, 31 Mar 2026 09:44:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1774975472; x=1775580272; darn=kvack.org; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=P9H7DtjUvqhXDyY5pBkhMdsDwbb7SsdQitFkTuKYIC0=; b=XQIfmewb2tFK8rmvtQNEL3jEWZo6E34QSoQ0WnKw6syFINyAHzu5QGc3fUP28J7+hF YMzKAxwYOGl/WCHzHEK5AJpvBygz91Q9bRX7yaHM2GTeLHiVeqhIAg1ohpeSSfXPkmd/ FD0zB3JhR1wrglqrAkCoxw/Bnft/ZG42/6N+TFlk5Ll+TRFKxaVWtUbQBTP/OmiR2iIg K7RiwOJ2dm0uN/B48ue0ugbu2cghbZbdbO+OeIBLpqRHKLOKLbUlRUH9TpYM/T0yBCJr yF4GGqxswNr2uo1LuXgX/HR1r78vUVjMz0EswRIQfgvqL03iLTQkuotVOmx5yIsJK4D0 hVBQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1774975472; x=1775580272; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-gg:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=P9H7DtjUvqhXDyY5pBkhMdsDwbb7SsdQitFkTuKYIC0=; b=kPTRnItlU6jt4KgxuVEm//mVo+ICb1oMDBcl/Z8hwfpJx24F6Zl+a0OyPYD3RlxVHo DSWoLQusg+22Z5mbvYwdPBXRyJeWV+S5Hf3nwqOlJvoKgDuS1Gb1Bh/rWDpX9MN0BmMn iG/zvj4ZvPL+ZWdprJ/irTZ+5ZfwF37HQIAUKemiMYbVbnNnO97t7gqYUm3Es2P5VaCc Z1n+yGhgwAFdX43x0fpf3tzAo/AmDk2A2CONT+jumQzK2DlmNXfZ1rFbhKcY1FpLWusT fXYe3iFmpXLpotxJa5ba0e5CBAfHO/gooib4B7Eif6IYH+6RjBbCyA4IWXa4uwqMoh1E sOpg== X-Forwarded-Encrypted: i=1; AJvYcCVAPuItVn5PYZaIGRIEic6OwP75+5scZ2wDwUY/hFbgBpMIwF8AehoqswMmtza8nFGVCrJA308y4Q==@kvack.org X-Gm-Message-State: AOJu0YyflhsrStGF5lTtH5mlyI3L/E9BlXfpQjoF8DkS6Sfojt3zoOgy v2DfuS0s4nWByr5ny2Nfykp/abq1kGnpJRJ2zC8w3I28RPKTyYNsHn1ANbZgZk8x9w== X-Gm-Gg: ATEYQzxwDhsBUqMV+l1I68GHm210Uq83+pRsi6zeTQkSSxpObOAkGEz4tS11o54/ADz RTwbyKE8YFm1EgoeY76ZA0oD3fSUihaalTAIwUsHpjTt7uApjyyXQUha4eR5I2zU8iXhw4r3kj/ RWGx+WuGrml27N1CDB3/+yLJiBY3K+Yue9J3dKfBDqt0dw/472ibcv/ZFyOsivSY7XLIr/wXeO3 ZDZ1MvlqjEaE3D2VTvU7/T59beavyHF44VBwWuaa6eUlC8Xmibpqux+PLELPieHwJZH15rNwZFd hGeHzdYUPthNVN2a8svuql4p2geeH6aESvSYjZB0ZwzwEZUDJ3w6ksGNDAvuFKopWMyQK/1luD0 +5P8E3dQx0kJVQ3SnmH1OGpvNbXlVIxzFNS6i/CxHrp+90ZY+j89bbkTATtXaFGlXiBSBxOQUTP lzQZAB2TRKnRD+2sIt+UMSreIe/M6xIGhKptecimxxiI5k/eMLWDRcVL7QQMN8VT96/J6v+DeU1 TBlEHTjwCtK1LQK6rM6YNQ91oIn6duGePn3Y15L6Gq0GaBMGVdp2w== X-Received: by 2002:a17:902:ebc6:b0:2a7:87c2:fcde with SMTP id d9443c01a7336-2b268f14089mr297505ad.15.1774975471796; Tue, 31 Mar 2026 09:44:31 -0700 (PDT) Received: from [2a00:79e0:2eb0:8:7c3f:a173:3e15:575a] ([2a00:79e0:2eb0:8:7c3f:a173:3e15:575a]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c76917bacc2sm9459387a12.26.2026.03.31.09.44.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 31 Mar 2026 09:44:31 -0700 (PDT) Date: Tue, 31 Mar 2026 09:44:30 -0700 (PDT) From: David Rientjes To: Shakeel Butt cc: Andrew Morton , Vlastimil Babka , Suren Baghdasaryan , Michal Hocko , Brendan Jackman , Johannes Weiner , Zi Yan , Petr Mladek , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [patch v3] mm, page_alloc: reintroduce page allocation stall warning In-Reply-To: <69cb3957.5d0a0220.93499.af4cSMTPIN_ADDED_BROKEN@mx.google.com> Message-ID: References: <30945cc3-9c4d-94bb-e7e7-dde71483800c@google.com> <231154f8-a3c3-229a-31a7-f91ab8ec1773@google.com> <58a10940-e44c-a120-dd6e-ee9f480c4946@google.com> <371c86c8-1d47-bd70-b74c-769842718b1f@google.com> <69cb3957.5d0a0220.93499.af4cSMTPIN_ADDED_BROKEN@mx.google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: A9DF240009 X-Stat-Signature: tuaot43stii3bgs7dqce9m6hrjq7hasf X-HE-Tag: 1774975473-680375 X-HE-Meta: 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 lAymWHjo Z80Ei76FkvTtPnqX0Z1q45FBM6sptfxGrlhX/iFefiiNNcUiPcY/BiBVn6QSek4CZkkwtM8Jg/L6GT2uYSjJmuijH27pm9aZOHpAt2cQAg1CjTYBZNlWaaDC26yx9PGmX1cgkoE/f+XkGU6v1bzMlx22FgfFrNrqzrzg9OF6Ba2eeAM0/MRu1U4w2o6dtBYlt3AqzbynlEtRr5tnfK1gQoOmgi1x/XclLI6tcBWU+ZzACeHzqp4o/PIy6pD7mJ85PbpcQ3zfuaKltqGFhn53l21wmLdKtSQU1x9t94X4O3nMa1i2VRFs9f728RzPO5OY+ig/GZtPD9T5xmtLPWalLmcTCmxYZYbfACsF8W52bs+MrShO6e3k5WsHPte5yg1avJl9VRTh19g/ouBDtRlqby/ia47prnXtQbtlWRZ8KpkYvag8= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, 30 Mar 2026, Shakeel Butt wrote: > > Previously, we had warnings when a single page allocation took longer > > than reasonably expected. This was introduced in commit 63f53dea0c98 > > ("mm: warn about allocations which stall for too long"). > > > > The warning was subsequently reverted in commit 400e22499dd9 ("mm: don't > > warn about allocations which stall for too long") because it was possible > > to generate memory pressure that would effectively stall further progress > > through printk execution. > > > > Page allocation stalls in excess of 10 seconds are always useful to debug > > because they can result in severe userspace unresponsiveness. Adding > > this artifact can be used to correlate with userspace going out to lunch > > and to understand the state of memory at the time. > > > > There should be a reasonable expectation that this warning will never > > trigger given it is very passive, it will only be emitted when a page > > allocation takes longer than 10 seconds. If it does trigger, this > > reveals an issue that should be fixed: a single page allocation should > > never loop for more than 10 seconds without oom killing to make memory > > available. > > > > Unlike the original implementation, this implementation only reports > > stalls once for the system every 10 seconds. Otherwise, many concurrent > > reclaimers could spam the kernel log unnecessarily. Stalls are only > > reported when calling into direct reclaim. > > > > Acked-by: Vlastimil Babka (SUSE) > > Signed-off-by: David Rientjes > > Reviewed-by: Shakeel Butt > > I am hoping that the reason you are reintroducing these warnings is > because you already are seeing such cases in your production > environment. Do you have anything interesting to share? > We don't have this patch in our production environment (yet). We've been stress testing allocations for page faults with lots of concurrent skb allocations that can keep us persistently below the per-zone min watermarks and hope that this patch will shed some light on some unresponsiveness issues that we've encountered if/when it happens.