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Date:   Wed, 27 Apr 2022 13:34:20 -0700
From:   Andrew Morton <akpm@linux-foundation.org>
To:     Vlastimil Babka <vbabka@suse.cz>
Cc:     Alexey Dobriyan <adobriyan@gmail.com>,
        Matthew Wilcox <willy@infradead.org>,
        "Alex Xu (Hello71)" <alex_y_xu@yahoo.ca>,
        Daniel Colascione <dancol@google.com>,
        linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] mm/smaps_rollup: return empty file for kthreads instead
 of ESRCH
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On Thu, 14 Apr 2022 09:38:14 +0200 Vlastimil Babka <vbabka@suse.cz> wrote:

> > Returning ESRCH is better so that programs don't waste time reading and
> > closing empty files and instantiating useless inodes.
> 
> Hm, unfortunately I don't remember why I put return -ESRCH for this case in
> addition to get_proc_task() failing. I doubt it was a conscious decision to
> treat kthreads differently - I think I would have preferred consistency with
> maps/smaps.
> 
> Can the awk use case be fixed with some flag to make it ignore the errors?

This is all too hard.  I think I'll drop the patch for now.