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Date:   Mon, 15 Aug 2022 15:12:19 -0700
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Subject: Re: [PATCH v2] sched/all: Change all BUG_ON() instances in the
 scheduler to WARN_ON_ONCE()
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To:     Mel Gorman <mgorman@suse.de>, Ingo Molnar <mingo@kernel.org>
Cc:     Linus Torvalds <torvalds@linux-foundation.org>,
        David Hildenbrand <david@redhat.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        stable@vger.kernel.org, Andrew Morton <akpm@linux-foundation.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Axel Rasmussen <axelrasmussen@google.com>,
        Peter Xu <peterx@redhat.com>, Hugh Dickins <hughd@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Jason Gunthorpe <jgg@nvidia.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Juri Lelli <juri.lelli@redhat.com>,
        Vincent Guittot <vincent.guittot@linaro.org>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>
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From:   John Hubbard <jhubbard@nvidia.com>
In-Reply-To: <20220815144143.zjsiamw5y22bvgki@suse.de>
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On 8/15/22 07:41, Mel Gorman wrote:
> For the rest, I didn't see obvious recovery paths that would allow the
> system to run predictably. Any of them firing will have unpredictable
> consequences (e.g. move_queued_task firing would be fun if it was a per-cpu
> kthread). Depending on which warning triggers, the remaining life of the
> system may be very short but maybe long enough to be logged even if system
> locks up shortly afterwards.

Hi Mel,

Are you basically saying, "WARN_ON*() seems acceptable in mm/, because
we can at least get the problem logged before it locks up, probably"?

Or are you implying that we should instead introduce and use some new
PANIC_ON() or VM_PANIC_ON() set of macros that would allow proper "log
then reboot" behavior?


thanks,
-- 
John Hubbard
NVIDIA