linux-kernel - Re: [PATCH] mm: use in_atomic() in print_vma

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Date:   Fri, 3 Nov 2017 20:09:49 +0000
From:   Bart Van Assche <Bart.VanAssche@....com>
To:     "yang.s@...baba-inc.com" <yang.s@...baba-inc.com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
CC:     "joe@...ches.com" <joe@...ches.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "mhocko@...nel.org" <mhocko@...nel.org>,
        "mingo@...hat.com" <mingo@...hat.com>
Subject: Re: [PATCH] mm: use in_atomic() in print_vma_addr()

On Fri, 2017-11-03 at 11:02 -0700, Andrew Morton wrote:
> Also, checkpatch says
> 
> WARNING: use of in_atomic() is incorrect outside core kernel code
> #43: FILE: mm/memory.c:4491:
> +       if (in_atomic())
> 
> I don't recall why we did that, but perhaps this should be revisited?

Is the comment above in_atomic() still up-to-date? From <linux/preempt.h>:

/*
 * Are we running in atomic context?  WARNING: this macro cannot
 * always detect atomic context; in particular, it cannot know about
 * held spinlocks in non-preemptible kernels.  Thus it should not be
 * used in the general case to determine whether sleeping is possible.
 * Do not use in_atomic() in driver code.
 */
#define in_atomic()	(preempt_count() != 0)

Bart.