From: guoren@kernel.org
To: arnd@arndb.de, guoren@kernel.org, palmer@rivosinc.com,
tglx@linutronix.de, peterz@infradead.org, luto@kernel.org,
conor.dooley@microchip.com, heiko@sntech.de, jszhang@kernel.org,
lazyparser@gmail.com, falcon@tinylab.org, chenhuacai@kernel.org,
apatel@ventanamicro.com, atishp@atishpatra.org,
palmer@dabbelt.com, paul.walmsley@sifive.com,
mark.rutland@arm.com, zouyipeng@huawei.com,
bigeasy@linutronix.de, David.Laight@aculab.com
Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-riscv@lists.infradead.org,
Guo Ren <guoren@linux.alibaba.com>
Subject: [PATCH V5 06/11] entry: Prevent DEBUG_PREEMPT warning
Date: Sun, 18 Sep 2022 11:52:41 -0400 [thread overview]
Message-ID: <20220918155246.1203293-7-guoren@kernel.org> (raw)
In-Reply-To: <20220918155246.1203293-1-guoren@kernel.org>
From: Guo Ren <guoren@linux.alibaba.com>
When DEBUG_PREEMPT=y,
exit_to_user_mode_prepare
->tick_nohz_user_enter_prepare
->tick_nohz_full_cpu(smp_processor_id())
->smp_processor_id()
->debug_smp_processor_id()
->check preempt_count() then:
[ 5.717610] BUG: using smp_processor_id() in preemptible [00000000]
code: S20urandom/94
[ 5.718111] caller is debug_smp_processor_id+0x24/0x38
[ 5.718417] CPU: 1 PID: 94 Comm: S20urandom Not tainted
6.0.0-rc3-00010-gfd0a0d619c63-dirty #238
[ 5.718886] Hardware name: riscv-virtio,qemu (DT)
[ 5.719136] Call Trace:
[ 5.719281] [<ffffffff800055fc>] dump_backtrace+0x2c/0x3c
[ 5.719566] [<ffffffff80ae6cb0>] show_stack+0x44/0x5c
[ 5.720023] [<ffffffff80aee870>] dump_stack_lvl+0x74/0xa4
[ 5.720557] [<ffffffff80aee8bc>] dump_stack+0x1c/0x2c
[ 5.721033] [<ffffffff80af65c0>]
check_preemption_disabled+0x104/0x108
[ 5.721538] [<ffffffff80af65e8>] debug_smp_processor_id+0x24/0x38
[ 5.722001] [<ffffffff800aee30>] exit_to_user_mode_prepare+0x48/0x178
[ 5.722355] [<ffffffff80af5bf4>] irqentry_exit_to_user_mode+0x18/0x30
[ 5.722685] [<ffffffff80af5c70>] irqentry_exit+0x64/0xa4
[ 5.722953] [<ffffffff80af52f4>] do_page_fault+0x1d8/0x544
[ 5.723291] [<ffffffff80003310>] ret_from_exception+0x0/0xb8
(Above is found in riscv platform with generic_entry)
The smp_processor_id() needs irqs disable or preempt_disable, so use
preempt dis/in protecting the tick_nohz_user_enter_prepare().
Signed-off-by: Guo Ren <guoren@linux.alibaba.com>
Signed-off-by: Guo Ren <guoren@kernel.org>
---
kernel/entry/common.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/kernel/entry/common.c b/kernel/entry/common.c
index 063068a9ea9b..36e4cd50531c 100644
--- a/kernel/entry/common.c
+++ b/kernel/entry/common.c
@@ -194,8 +194,10 @@ static void exit_to_user_mode_prepare(struct pt_regs *regs)
lockdep_assert_irqs_disabled();
+ preempt_disable();
/* Flush pending rcuog wakeup before the last need_resched() check */
tick_nohz_user_enter_prepare();
+ preempt_enable();
if (unlikely(ti_work & EXIT_TO_USER_MODE_WORK))
ti_work = exit_to_user_mode_loop(regs, ti_work);
--
2.36.1
next prev parent reply other threads:[~2022-09-18 15:54 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-18 15:52 [PATCH V5 00/11] riscv: Add GENERIC_ENTRY support and related features guoren
2022-09-18 15:52 ` [PATCH V5 01/11] riscv: elf_kexec: Fixup compile warning guoren
2022-09-18 15:52 ` [PATCH V5 02/11] riscv: compat_syscall_table: " guoren
2022-09-18 15:52 ` [PATCH V5 03/11] riscv: ptrace: Remove duplicate operation guoren
2022-09-18 15:52 ` [PATCH V5 04/11] compiler_types.h: Add __noinstr_section() for noinstr guoren
2022-09-18 15:52 ` [PATCH V5 05/11] riscv: traps: Add noinstr to prevent instrumentation inserted guoren
2022-09-18 15:52 ` guoren [this message]
2022-09-19 11:58 ` [PATCH V5 06/11] entry: Prevent DEBUG_PREEMPT warning Peter Zijlstra
2022-09-20 1:45 ` Guo Ren
2022-09-30 12:27 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 07/11] riscv: convert to generic entry guoren
2022-09-19 13:34 ` Peter Zijlstra
2022-09-20 6:36 ` Guo Ren
2022-09-20 7:22 ` Peter Zijlstra
2022-09-30 11:28 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 08/11] riscv: Support HAVE_IRQ_EXIT_ON_IRQ_STACK guoren
2022-09-19 13:45 ` Peter Zijlstra
2022-09-20 6:08 ` Guo Ren
2022-09-20 7:27 ` Peter Zijlstra
2022-09-20 7:34 ` Peter Zijlstra
2022-09-21 6:16 ` Guo Ren
2022-09-21 8:34 ` Chen Zhongjin
2022-09-21 9:53 ` Guo Ren
2022-09-21 11:56 ` Chen Zhongjin
2022-09-22 1:26 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 09/11] riscv: Support HAVE_SOFTIRQ_ON_OWN_STACK guoren
2022-09-20 0:11 ` Guo Ren
2022-09-18 15:52 ` [PATCH V5 10/11] riscv: Add config of thread stack size guoren
2022-09-18 15:52 ` [PATCH V5 11/11] riscv: Add support for STACKLEAK gcc plugin guoren
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