linux-kernel - Re: [PATCH] x86/show_trace_log_lvl: ensure stack pointer is aligned, again

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Message-ID: <20230428043158.r5omehiaqawcac2y@treble>
Date:   Thu, 27 Apr 2023 21:31:58 -0700
From:   Josh Poimboeuf <jpoimboe@...nel.org>
To:     Oleg Nesterov <oleg@...hat.com>
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vernon Lovejoy <vlovejoy@...hat.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86/show_trace_log_lvl: ensure stack pointer is aligned,
 again

On Thu, Apr 27, 2023 at 04:00:54PM +0200, Oleg Nesterov wrote:
> diff --git a/arch/x86/kernel/dumpstack.c b/arch/x86/kernel/dumpstack.c
> index 0bf6779187dd..71ab445a29c3 100644
> --- a/arch/x86/kernel/dumpstack.c
> +++ b/arch/x86/kernel/dumpstack.c
> @@ -214,6 +214,7 @@ static void show_trace_log_lvl(struct task_struct *task, struct pt_regs *regs,
>  	 * - hardirq stack
>  	 * - entry stack
>  	 */
> +	stack = PTR_ALIGN(stack, sizeof(long));
>  	for ( ; stack; stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {
>  		const char *stack_name;

Seems reasonable, though 'stack' is already initialized a few lines
above this, so it would be cleaner to do the PTR_ALIGN then.  Or even
better, just move it all to the for loop:

	for (stack = PTR_ALIGN(stack ? : get_stack_pointer(task, regs));
	     stack;
	     stack = PTR_ALIGN(stack_info.next_sp, sizeof(long))) {

-- 
Josh