From: Peter Zijlstra <peterz@infradead.org>
To: Michal Hocko <mhocko@kernel.org>
Cc: Bart Van Assche <Bart.VanAssche@wdc.com>,
"yang.s@alibaba-inc.com" <yang.s@alibaba-inc.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"joe@perches.com" <joe@perches.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"mingo@redhat.com" <mingo@redhat.com>
Subject: Re: [PATCH] mm: use in_atomic() in print_vma_addr()
Date: Mon, 6 Nov 2017 11:05:58 +0100 [thread overview]
Message-ID: <20171106100558.GD3165@worktop.lehotels.local> (raw)
In-Reply-To: <20171105081946.yr2pvalbegxygcky@dhcp22.suse.cz>
On Sun, Nov 05, 2017 at 09:19:46AM +0100, Michal Hocko wrote:
> [CC Peter]
>
> On Fri 03-11-17 20:09:49, Bart Van Assche wrote:
> > 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)
>
> I can still see preempt_disable NOOP for !CONFIG_PREEMPT_COUNT kernels
> which makes me think this is still a valid comment.
Yes the comment is very much accurate.
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next prev parent reply other threads:[~2017-11-06 10:06 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-11-01 21:38 [PATCH] mm: use in_atomic() in print_vma_addr() Yang Shi
2017-11-02 7:57 ` Michal Hocko
2017-11-02 17:44 ` Yang Shi
2017-11-03 8:29 ` Michal Hocko
2017-11-03 18:02 ` Andrew Morton
2017-11-03 18:16 ` Yang Shi
2017-11-03 20:09 ` Bart Van Assche
2017-11-05 8:19 ` Michal Hocko
2017-11-06 10:05 ` Peter Zijlstra [this message]
2017-11-06 10:43 ` Michal Hocko
2017-11-06 10:56 ` Michal Hocko
2017-11-06 12:00 ` Peter Zijlstra
2017-11-06 12:12 ` Michal Hocko
2017-11-06 13:40 ` [PATCH] mm: do not rely on preempt_count in print_vma_addr (was: Re: [PATCH] mm: use in_atomic() in print_vma_addr()) Michal Hocko
2017-11-06 14:19 ` [PATCH] mm: do not rely on preempt_count in print_vma_addr Vlastimil Babka
2017-11-06 14:28 ` Michal Hocko
2017-11-06 16:16 ` Yang Shi
2017-11-06 16:24 ` Michal Hocko
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