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 X-Spam-Level: X-Spam-Status: No, score=-17.4 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT, USER_IN_DEF_DKIM_WL autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 01774C43331 for ; Thu, 26 Mar 2020 16:33:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CBC6A21D81 for ; Thu, 26 Mar 2020 16:33:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="QlyYPdUE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728600AbgCZQdO (ORCPT ); Thu, 26 Mar 2020 12:33:14 -0400 Received: from mail-wm1-f74.google.com ([209.85.128.74]:54292 "EHLO mail-wm1-f74.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727752AbgCZQdO (ORCPT ); Thu, 26 Mar 2020 12:33:14 -0400 Received: by mail-wm1-f74.google.com with SMTP id t22so2408778wmt.4 for ; Thu, 26 Mar 2020 09:33:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=cj1yXAqU8AkYqnSowOMnKDwXe28Nmz4NKXcTv1E5rr8=; b=QlyYPdUEjthYFChxgCVdTAxTBsSjtTEujh8fKUyVe2X1M4qIaDAIIGpHdB3HEuhn8O QEHyMF0kfFNraTl/rH78GO9+Ome/PyBhr0br3HrVEZ1FPPb8WWaI50wDtJOyiz3DL/eY 5f5b7/Fm9M/hKVDEMkK2nYbOYR2Tp5CpPa9azj8zpoXjyXMOTGjAf/ata6fYlw+vdMXg lTUrS96iVX9uKMVnqLc6Fn3RtkI0rAVGhJWje4JdlfDWrgXURBOnllcC/ZyjlGS3aFlD Cm/8BXBTIPSl22F9vQxx0Dxngmircdao+AmRW3bnMOsux8FVfdbIWZ18ERPGH609bz/o 1lVQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=cj1yXAqU8AkYqnSowOMnKDwXe28Nmz4NKXcTv1E5rr8=; b=NdjHYWD7OPa2iVWzQsaZSczQpYIqsWHFNpXkjiA0VXEq9FExO1Fzu8Y1tUC64cFfni KrdFBnJDZv4Av7rLdLiV2H3fcI0cmrloDLtwx4Uqjve8cP66MEPzcE8xjWDDWRH5YDY6 MAdHPj0bDSqt4nmpmaay1xUHJfGXV4WhbxlzcktI3+/KNObGxiVmykZZNri5RHClh02u RSG/yQHstUu5irempsYnPp/XxdbMaKosYmPk6POW/L/Mz8bh8a86OwizgaAIFI7/f26A 3/lmn/H3Fdl/jnAU5NxtxbJ437gfsPZmb3XioRj1oX0R/2jxQXKoP5mw6p1YzlKBnqbs c86w== X-Gm-Message-State: ANhLgQ3EGP+aoSvRak4GN/iIA5ikC0+VcON4MxMndz2wAR5iOyvXWVxT UpxAu3+uqgdeEOA8mFfVer9E7weTAg== X-Google-Smtp-Source: ADFU+vt4y7onh9o9+kAT94HkWd8Pf04QxJp3qnGSHOe6xI1l+AZna1QGr4UpTELU485gJTHK1dqLBpbWxA== X-Received: by 2002:adf:ea03:: with SMTP id q3mr9842558wrm.267.1585240391265; Thu, 26 Mar 2020 09:33:11 -0700 (PDT) Date: Thu, 26 Mar 2020 17:32:44 +0100 In-Reply-To: <20200326163245.119670-1-jannh@google.com> Message-Id: <20200326163245.119670-2-jannh@google.com> Mime-Version: 1.0 References: <20200326163245.119670-1-jannh@google.com> X-Mailer: git-send-email 2.25.1.696.g5e7596f4ac-goog Subject: [PATCH 1/2] irq_work: Reinitialize list heads for secondary CPUs From: Jann Horn To: Peter Zijlstra , Petr Mladek , Sergey Senozhatsky Cc: linux-kernel@vger.kernel.org, Dennis Zhou , Tejun Heo , Christoph Lameter , Steven Rostedt , Thomas Gleixner , Frederic Weisbecker Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When printk_deferred() is used before percpu initialization, it will queue up lazy IRQ work on the boot CPU; percpu initialization then copies the work list head to all secondary CPUs. To ensure that the secondary CPUs don't re-execute the boot CPU's work and whatever its ->next pointer leads to, zero out the secondary CPUs' work list heads before bringing up SMP. Signed-off-by: Jann Horn --- kernel/irq_work.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) diff --git a/kernel/irq_work.c b/kernel/irq_work.c index 828cc30774bc..903e5be9aebf 100644 --- a/kernel/irq_work.c +++ b/kernel/irq_work.c @@ -152,6 +152,7 @@ static void irq_work_run_list(struct llist_head *list) * while we are in the middle of the func. */ flags = atomic_fetch_andnot(IRQ_WORK_PENDING, &work->flags); + WARN_ON_ONCE((flags & IRQ_WORK_PENDING) == 0); work->func(work); /* @@ -195,3 +196,24 @@ void irq_work_sync(struct irq_work *work) cpu_relax(); } EXPORT_SYMBOL_GPL(irq_work_sync); + +/* + * If we queued up IRQ work before fully initializing the percpu subsystem, e.g. + * via printk_deferred(), the head pointer of the boot CPU will have been copied + * over to all the other CPUs. + * To fix that, manually initialize the list heads of all secondary processors + * before bringing up SMP. + */ +static int __init irq_work_percpu_fixup(void) +{ + int cpu; + + for_each_possible_cpu(cpu) { + if (cpu == smp_processor_id()) + continue; + per_cpu(raised_list.first, cpu) = NULL; + per_cpu(lazy_list.first, cpu) = NULL; + } + return 0; +} +early_initcall(irq_work_percpu_fixup) -- 2.25.1.696.g5e7596f4ac-goog