From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-180.mta0.migadu.com (out-180.mta0.migadu.com [91.218.175.180]) (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 8F86128468E for ; Tue, 31 Mar 2026 03:02:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.180 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774926160; cv=none; b=jxdi8SiZckJL6OPv6dd4CHXIg8xt/r1Yyh3aQ1+fhYNpFUP4Bg/vtZV04xYF2YgV35Uom5S5jNiGhe1w/49aM3ogbMwit4+D+/cjxomDhbpRU2/UDV9+36NYhVTAb8X6tALPPicuT7dcF4tbeq0jcJgrY6U3Afejz0WNlMtVng8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774926160; c=relaxed/simple; bh=yP7r+dIWD8nMvxHExLTNiSj69aK5L1ih4jGtfpkQScg=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Jy+L/Nu3PASlTYnsQ1HxpIbjSBIPwXQVR7H1j7AQJ82Jj8jwLhnOiC+8Agoe+6KebDYdePZbMxyAblqFvkIu7gcfrBzhGiFxJ+aDuEy7jh3v8zwTI1NB9iD61QkGZGa0baAMN6PzoacnY19448w63h0hOTNCk1tdQ2J4Zrq7cAY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=AjfzNudJ; arc=none smtp.client-ip=91.218.175.180 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="AjfzNudJ" Date: Mon, 30 Mar 2026 20:02:28 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1774926156; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=tcgf/nnaWd6CtKz6QeNTxmCGWplJP0pcuH1q2jZJj0U=; b=AjfzNudJ+37u2+bTzacJSPj7Y7zPpLOERw1g9uBPVSKcibUf86ePoyN72cc1vPJHdr2HFE skRaNLjBx4b6Ym1bSo8gkexoLRfAtQ8g73XyBAVC6Gq99djw9WqkE8eGZjrxRUY77Hiveu dAoPCCQ8p6yfJGnets+tnYQTGRyINv0= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Shakeel Butt To: David Rientjes 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 Message-ID: <20260331030102.GA615109@shakeel.butt@linux.dev> 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <371c86c8-1d47-bd70-b74c-769842718b1f@google.com> X-Migadu-Flow: FLOW_OUT On Mon, Mar 30, 2026 at 06:20:57PM -0700, David Rientjes 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?