From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Oleg Nesterov <oleg@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@kernel.org>, Phil Auld <pauld@redhat.com>,
Frederic Weisbecker <frederic@kernel.org>,
Sasha Levin <sashal@kernel.org>,
mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com,
vincent.guittot@linaro.org
Subject: [PATCH AUTOSEL 6.1 12/12] sched/isolation: Fix boot crash when maxcpus < first housekeeping CPU
Date: Tue, 7 May 2024 19:00:14 -0400 [thread overview]
Message-ID: <20240507230031.391436-12-sashal@kernel.org> (raw)
In-Reply-To: <20240507230031.391436-1-sashal@kernel.org>
From: Oleg Nesterov <oleg@redhat.com>
[ Upstream commit 257bf89d84121280904800acd25cc2c444c717ae ]
housekeeping_setup() checks cpumask_intersects(present, online) to ensure
that the kernel will have at least one housekeeping CPU after smp_init(),
but this doesn't work if the maxcpus= kernel parameter limits the number of
processors available after bootup.
For example, a kernel with "maxcpus=2 nohz_full=0-2" parameters crashes at
boot time on a virtual machine with 4 CPUs.
Change housekeeping_setup() to use cpumask_first_and() and check that the
returned CPU number is valid and less than setup_max_cpus.
Another corner case is "nohz_full=0" on a machine with a single CPU or with
the maxcpus=1 kernel argument. In this case non_housekeeping_mask is empty
and tick_nohz_full_setup() makes no sense. And indeed, the kernel hits the
WARN_ON(tick_nohz_full_running) in tick_sched_do_timer().
And how should the kernel interpret the "nohz_full=" parameter? It should
be silently ignored, but currently cpulist_parse() happily returns the
empty cpumask and this leads to the same problem.
Change housekeeping_setup() to check cpumask_empty(non_housekeeping_mask)
and do nothing in this case.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Phil Auld <pauld@redhat.com>
Acked-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/r/20240413141746.GA10008@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/sched/isolation.c | 7 ++++++-
1 file changed, 6 insertions(+), 1 deletion(-)
diff --git a/kernel/sched/isolation.c b/kernel/sched/isolation.c
index 373d42c707bc5..82e2f7fc7c267 100644
--- a/kernel/sched/isolation.c
+++ b/kernel/sched/isolation.c
@@ -109,6 +109,7 @@ static void __init housekeeping_setup_type(enum hk_type type,
static int __init housekeeping_setup(char *str, unsigned long flags)
{
cpumask_var_t non_housekeeping_mask, housekeeping_staging;
+ unsigned int first_cpu;
int err = 0;
if ((flags & HK_FLAG_TICK) && !(housekeeping.flags & HK_FLAG_TICK)) {
@@ -129,7 +130,8 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
cpumask_andnot(housekeeping_staging,
cpu_possible_mask, non_housekeeping_mask);
- if (!cpumask_intersects(cpu_present_mask, housekeeping_staging)) {
+ first_cpu = cpumask_first_and(cpu_present_mask, housekeeping_staging);
+ if (first_cpu >= nr_cpu_ids || first_cpu >= setup_max_cpus) {
__cpumask_set_cpu(smp_processor_id(), housekeeping_staging);
__cpumask_clear_cpu(smp_processor_id(), non_housekeeping_mask);
if (!housekeeping.flags) {
@@ -138,6 +140,9 @@ static int __init housekeeping_setup(char *str, unsigned long flags)
}
}
+ if (cpumask_empty(non_housekeeping_mask))
+ goto free_housekeeping_staging;
+
if (!housekeeping.flags) {
/* First setup call ("nohz_full=" or "isolcpus=") */
enum hk_type type;
--
2.43.0
prev parent reply other threads:[~2024-05-07 23:01 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-05-07 23:00 [PATCH AUTOSEL 6.1 01/12] wifi: mac80211: don't use rate mask for scanning Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 02/12] wifi: mac80211: ensure beacon is non-S1G prior to extracting the beacon timestamp field Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 03/12] wifi: cfg80211: fix the order of arguments for trace events of the tx_rx_evt class Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 04/12] dt-bindings: rockchip: grf: Add missing type to 'pcie-phy' node Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 05/12] net: usb: qmi_wwan: add Telit FN920C04 compositions Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 06/12] drm/amd/display: Set color_mgmt_changed to true on unsuspend Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 07/12] drm/amdgpu: Update BO eviction priorities Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 08/12] drm/amdgpu: Fix the ring buffer size for queue VM flush Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 09/12] drm/amdgpu/mes: fix use-after-free issue Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 10/12] LoongArch: Lately init pmu after smp is online Sasha Levin
2024-05-07 23:00 ` [PATCH AUTOSEL 6.1 11/12] selftests: sud_test: return correct emulated syscall value on RISC-V Sasha Levin
2024-05-07 23:00 ` Sasha Levin [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20240507230031.391436-12-sashal@kernel.org \
--to=sashal@kernel.org \
--cc=frederic@kernel.org \
--cc=juri.lelli@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@kernel.org \
--cc=mingo@redhat.com \
--cc=oleg@redhat.com \
--cc=pauld@redhat.com \
--cc=peterz@infradead.org \
--cc=stable@vger.kernel.org \
--cc=tglx@linutronix.de \
--cc=vincent.guittot@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).