From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 985675C8F7; Sat, 21 Dec 2024 03:57:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734753446; cv=none; b=IaXKwHF2eLpyCB5P/GbW0grcrWsdOy0k7wXMZ9LIfKJ5RF9fvgNtOiUyXeF/mk2mTviDWURdDo0fgSILngjV+AFVYdNoFoAdv8NUZe4/j41CpWsTe1NmEDq1xZEvgGwu0IaXWiA2JqUYWzxHBIsHG2oxR9bIgpeVmsPm7Tg+UaM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734753446; c=relaxed/simple; bh=PiIPBe0UUPa7OxWNxW5c8SxznkJstqepPuAZSArOjOw=; h=Date:To:From:Subject:Message-Id; b=KDXP5/5nIU1chIW6EBY1zaQR+PLC1fMBP21rGwp1XTeEeuRVUdxNKxs5W3z8HTvHqJNnpxftCjXtRmPWQhffubZYRWR605ohTmg9kStlnmsNMz1Jkn4Io4gdk61KVr/wRT7p4QHUVhyiVPrkmHL6w65tvjXLsnOM6PYa5i6CcyA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=MvFYgfRI; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="MvFYgfRI" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38C82C4CECE; Sat, 21 Dec 2024 03:57:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1734753446; bh=PiIPBe0UUPa7OxWNxW5c8SxznkJstqepPuAZSArOjOw=; h=Date:To:From:Subject:From; b=MvFYgfRIpv4YVMe+ay6kERAagZqLgyhJnYvG5AaeeYC2c8MNEtMHMYztoAIPjf0vI RDxbCczoK9IvmtTfZA5pkZ1Qxil5offFfkgbCs9X57x83JNHd3MOg33Z5rFb3slFYn 2WYdaGqiHyN47LzoaPp40cV0gUY+OZmV+lKapSag= Date: Fri, 20 Dec 2024 19:57:25 -0800 To: mm-commits@vger.kernel.org,stable@vger.kernel.org,bigeasy@linutronix.de,koichiro.den@canonical.com,akpm@linux-foundation.org From: Andrew Morton Subject: + vmstat-disable-vmstat_work-on-vmstat_cpu_down_prep.patch added to mm-hotfixes-unstable branch Message-Id: <20241221035726.38C82C4CECE@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: vmstat: disable vmstat_work on vmstat_cpu_down_prep() has been added to the -mm mm-hotfixes-unstable branch. Its filename is vmstat-disable-vmstat_work-on-vmstat_cpu_down_prep.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/vmstat-disable-vmstat_work-on-vmstat_cpu_down_prep.patch This patch will later appear in the mm-hotfixes-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Koichiro Den Subject: vmstat: disable vmstat_work on vmstat_cpu_down_prep() Date: Sat, 21 Dec 2024 12:33:20 +0900 Even after mm/vmstat:online teardown, shepherd may still queue work for the dying cpu until the cpu is removed from online mask. While it's quite rare, this means that after unbind_workers() unbinds a per-cpu kworker, it potentially runs vmstat_update for the dying CPU on an irrelevant cpu before entering atomic AP states. When CONFIG_DEBUG_PREEMPT=y, it results in the following error with the backtrace. BUG: using smp_processor_id() in preemptible [00000000] code: \ kworker/7:3/1702 caller is refresh_cpu_vm_stats+0x235/0x5f0 CPU: 0 UID: 0 PID: 1702 Comm: kworker/7:3 Tainted: G Tainted: [N]=TEST Workqueue: mm_percpu_wq vmstat_update Call Trace: dump_stack_lvl+0x8d/0xb0 check_preemption_disabled+0xce/0xe0 refresh_cpu_vm_stats+0x235/0x5f0 vmstat_update+0x17/0xa0 process_one_work+0x869/0x1aa0 worker_thread+0x5e5/0x1100 kthread+0x29e/0x380 ret_from_fork+0x2d/0x70 ret_from_fork_asm+0x1a/0x30 So, for mm/vmstat:online, disable vmstat_work reliably on teardown and symmetrically enable it on startup. Link: https://lkml.kernel.org/r/20241221033321.4154409-1-koichiro.den@canonical.com Signed-off-by: Koichiro Den Cc: Sebastian Andrzej Siewior Cc: Signed-off-by: Andrew Morton --- mm/vmstat.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) --- a/mm/vmstat.c~vmstat-disable-vmstat_work-on-vmstat_cpu_down_prep +++ a/mm/vmstat.c @@ -2148,13 +2148,14 @@ static int vmstat_cpu_online(unsigned in if (!node_state(cpu_to_node(cpu), N_CPU)) { node_set_state(cpu_to_node(cpu), N_CPU); } + enable_delayed_work(&per_cpu(vmstat_work, cpu)); return 0; } static int vmstat_cpu_down_prep(unsigned int cpu) { - cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu)); + disable_delayed_work_sync(&per_cpu(vmstat_work, cpu)); return 0; } _ Patches currently in -mm which might be from koichiro.den@canonical.com are vmstat-disable-vmstat_work-on-vmstat_cpu_down_prep.patch hugetlb-prioritize-surplus-allocation-from-current-node.patch