[BUG] KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_next_event

From: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
To: linux-kernel@vger.kernel.org
Cc: Frederic Weisbecker <frederic@kernel.org>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>
Subject: [BUG] KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_next_event
Date: Thu, 17 Aug 2023 21:32:41 +0200	[thread overview]
Message-ID: <40ac9903-469a-b1ea-4339-8b06f855450e@alu.unizg.hr> (raw)

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Hi,

This is your friendly bug reporter. :-)

The environment is the vanilla torvalds kernel on Ubuntu 22.04 LTS and a Ryzen 7950X assembled box.

[ 7145.500079] ==================================================================
[ 7145.500109] BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_next_event

[ 7145.500139] write to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 26:
[ 7145.500155]  tick_nohz_idle_stop_tick+0x3b1/0x4a0
[ 7145.500173]  do_idle+0x1e3/0x250
[ 7145.500186]  cpu_startup_entry+0x20/0x30
[ 7145.500199]  start_secondary+0x129/0x160
[ 7145.500216]  secondary_startup_64_no_verify+0x17e/0x18b

[ 7145.500245] read to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 16:
[ 7145.500261]  tick_nohz_next_event+0xe7/0x1e0
[ 7145.500277]  tick_nohz_get_sleep_length+0xa7/0xe0
[ 7145.500293]  menu_select+0x82/0xb90
[ 7145.500309]  cpuidle_select+0x44/0x60
[ 7145.500324]  do_idle+0x1c2/0x250
[ 7145.500336]  cpu_startup_entry+0x20/0x30
[ 7145.500350]  start_secondary+0x129/0x160
[ 7145.500367]  secondary_startup_64_no_verify+0x17e/0x18b

[ 7145.500392] value changed: 0x0000001a -> 0xffffffff

[ 7145.500411] Reported by Kernel Concurrency Sanitizer on:
[ 7145.500421] CPU: 16 PID: 0 Comm: swapper/16 Tainted: G             L     6.5.0-rc6-net-cfg-kcsan-00038-g16931859a650 #35
[ 7145.500439] Hardware name: ASRock X670E PG Lightning/X670E PG Lightning, BIOS 1.21 04/26/2023
[ 7145.500449] ==================================================================

Please find dmesg log (what was available in the ring buffer) and the lshw output attached.

NOTE: There are no proprietary drivers loaded and Canonical livepatch isn't working for this kernel,
probably previous ACPI KCSAN BUGs turn this taint on.

Thank you very much for your time evaluating this report.

Best regards,
Mirsad Todorovac

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