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 DA6B3C61DE2 for ; Mon, 31 Aug 2026 10:29:02 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 894656B0088; Mon, 31 Aug 2026 06:29:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 844CC6B008A; Mon, 31 Aug 2026 06:29:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 733F86B008C; Mon, 31 Aug 2026 06:29:01 -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 4BC1A6B0088 for ; Mon, 31 Aug 2026 06:29:01 -0400 (EDT) Received: from smtpin25.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay01.hostedemail.com (Postfix) with ESMTP id C6DB71C1FAA for ; Mon, 31 Aug 2026 10:29:00 +0000 (UTC) X-FDA: 85161191640.25.0337A84 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by imf26.hostedemail.com (Postfix) with ESMTP id 2CCB214000C for ; Mon, 31 Aug 2026 10:28:59 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=JYkRuxX8; dkim=pass header.d=linutronix.de header.s=2020e header.b=Et4TbARV; spf=pass (imf26.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1788172139; 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=oXHuqEMVd5r9Kb5uP27u7BqXJjMjwilyDDUTebyzQX4=; b=pxeyyyMN73Egh9OY8Tm1lou+CSkk1BUccj6QRCnkg2Bo0pjv7SGFJn9gKjpNaFxayr6D09 PAJ6car5k4SCrBJUvnTon3LcZ4/+U9LUmuF1KTHThelRW5KaWl0eWeu6Z99OUcOzfbISfJ /Gy14/l+nDG60S5unIc6WUy7o4+2MHU= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1788172139; b=EfmYDQhmgxM+kX6IH4VAsTiOkQ+MnFkEE9adxA0+C8H3DQPDMbVR7MqszOnnARRyPYgDOz 3SI9mU/pn3ycc2o9sLY0Tj+4oPgbD/eqlsS8RRO3mVKSrBgqCIdvzeq8j+oSGz4mZ5S0Vt TPiYtu/XHZmWj9brp3DO4CDI7T9Rm+Q= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=linutronix.de header.s=2020 header.b=JYkRuxX8; dkim=pass header.d=linutronix.de header.s=2020e header.b=Et4TbARV; spf=pass (imf26.hostedemail.com: domain of bigeasy@linutronix.de designates 193.142.43.55 as permitted sender) smtp.mailfrom=bigeasy@linutronix.de; dmarc=pass (policy=none) header.from=linutronix.de Date: Mon, 31 Aug 2026 12:28:55 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1788172137; 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=oXHuqEMVd5r9Kb5uP27u7BqXJjMjwilyDDUTebyzQX4=; b=JYkRuxX83aiixALIH7LLrCuWfxOud3Br3FSshGL4xI3IdQvN9XSlMmu9UxGk6/A+5+c3DY Jfjy372gb3H7iLhwTdYDIiMBaXVgA6tz3qpal8gd1kBPJv60QkaQAB63M7EFco488RsIOJ MqFH//swaz9C0f5YOfAD+ftkHb5S2K6VvnOMLNn8u73TWwCYKqODgm/J/eGAWBg96bbOvx lX3QdIYs+VDnTM5Nc4ZTahOywMtiGqmYNIGFMQH6WKeFCHNX7EOUlC3KU2HhXJlcFxbnrP e+WMcoP0ACKGDnt0Y0WjylGZK4jJ2tSIoxyrhassfnyNylw59XtGAAh612xgBQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1788172137; 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=oXHuqEMVd5r9Kb5uP27u7BqXJjMjwilyDDUTebyzQX4=; b=Et4TbARVJGmOcZqp3pkQLXcVtfr7mVUu6imjMFJX/FcsrC3o9JIydz2OmEjj6aIWUr1Lev ICbpUTmyuxiUdpCQ== From: Sebastian Andrzej Siewior To: Hugh Dickins Cc: Shakeel Butt , syzbot , linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [mm?] WARNING in __mod_zone_page_state Message-ID: <20260831102855.TOx0U8Vi@linutronix.de> References: <6a931c5a.08e933ee.dbf97.0093.GAE@google.com> <4793259a-00da-ea31-8cbd-a6cb5bf48692@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <4793259a-00da-ea31-8cbd-a6cb5bf48692@google.com> X-Stat-Signature: 74y8oeqh4jc4hz8bw3pdzdm6b53kz3qj X-Rspamd-Queue-Id: 2CCB214000C X-Rspamd-Server: rspam02 X-Rspam-User: X-HE-Tag: 1788172139-204642 X-HE-Meta: U2FsdGVkX1+xZfSg8v6ewPhFOgJKQkzoM1LQbFLZzlvciIw2CZ5bDfUFWxZLPMeEWwaLhfl6gdfaX/tNWppHSph5leN5ff6I6+ZvSam63sD2DJH2ofne4ghibwORNK8ky0CBR5urRI+QuTD/JphJBp6oj6QjDxsIF+vk7N+tEQMYOS+wkMLDzdTQQkLtusiin61sQagW6xqpSx4menlRj9TJOSY+QsTa34Cf6IbHpwCjg5TWvJvpJIGnFO4FvwLdTsYOxHpQzRgksaZe5dFz1L5NTjxE7tbBd3ejgrzlU3My2sD2P86T3/y6bHKScq+zHWLpqRQUAYRU2g5s3zXm0lHvECal1wGt4hTFzE7VDnQIvS3gklI+gKLpUJw57dE5UItZDZkqrFP6i42sDivtXbJiVocTS8UzV7TDXzovjxKzDZ2Mfufuk1uJt7E4091zhDiHMkCCVpk2pq0rc9QDZBd0SUK5jDx6p2YtNtTyVKg1Gx16lB3tQX87lp/raOUgpkFE9p4Q3RGlLZVcVdI0zFsXUArYcyZSAblmlj7LuP8FU0s5dq8etylq3gfCLvALNy0dpTze0faPVp/AhmgYKVWBw+35X/FosX1CY8+HknHQ9ybwsIhamKfwzmG5Me4SEAK3C62UyUBcgBESsd17sXXESwooKlQDnmsFcGELI7zDx8d7dpdn+qhleYTCyJSo77cOLPfKdigEpSHgWLeSIS+JXRaNtDrzxaIZ5rI4nyO5rdXk+pllPbLXvicxpeyjZQuFbU22lIeET2QJgxdnHNvEE/GrdsmF7d58lkhcHfO3/ypDcCVhxw341SXfCfbCVQFrC6c6PjiGAhAhy56gCbVfdZha1bWaaFC/ECuOqjkzrOT3rJ6iIbbis0Ywgp8QKsHiY6qUDhfITbTJQRJtsVKZI/7/Gtm0I0xmQs9jU0jsdYMSPfNP6eLs1WWa+wz5hrUE9msbl+lxp+8dgmN Aub75gjn zrdrfR9wHISPrAyDCddvVSmMjY/gCdDXf1ofn4ljF+NGu9SdoEou32sE9AD6FQHn/7AT4Rl4j1P1IVYAxQ8vcNAVwBkvybJANi3dpPHeh0INLEJ0nJ+Pe6MWjkLx7syUozInix05XUkKXj6/LN/6MXDHx0dwz82pQXBOSQdF9EDc6TyRHjiWJ6N52bYhVTBDFdUOwxg4BWM7ignHJmG3Vn2+zs+bx+2kDu7pQ/5d/5yZMYO035/W/KiFtkRhJdnZEv6w0fuoLBWamRr445NSN0QXNrI7B0SmjC4veqZcQT1riolWdWfvclv8ayFViKRZnUNkxMyGtYNiQ9TGlZNCw4f43cO/BKY+NfptrlAOzattEPcKtUtW1LClb8T+OyNY5hQcIEAeWVZcHzIEyCyyMU2zWj6JqmtYrk/1E Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2026-08-30 10:29:46 [-0700], Hugh Dickins wrote: > Oh for the good old days when we were allowed to say preempt_disable()! I'm sorry for taking this away from you. > > --- a/mm/mlock.c > > +++ b/mm/mlock.c > > @@ -141,11 +141,16 @@ static struct lruvec *__munlock_folio(struct folio *folio, struct lruvec *lruvec > > > > munlock: > > if (folio_test_clear_mlocked(folio)) { > > - __zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages); > > + /* > > + * This runs both with and without the lruvec lock held, and > > + * mlock_drain_remote() reaches it fully preemptible, so use > > + * the accessors that serialize themselves. > > I'm very far from being a good advisor on PREEMPT_RT, > but I think that comment about lruvec lock would be wrong there. This change would eliminate the warning on !PREEMPT_RT and not cause any further trouble for PREEMPT_RT. Given that this it might mandate for WARN_ON_ONCE(IS_ENABLED(CONFIG_DEBUG_VM) && !IS_ENABLED(CONFIG_PREEMPT_RT) && !!irqs_disabled()); in __mod_zone_page_state() and other places where preempt_disable_nested() was added. The counters do rely on disabled interrupts not preemption. > Hugh Sebastian