linux-kernel - Re: [PATCH v2] mm/page_alloc: bail out on fatal signal during reclaim/compaction retry attempt

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Message-ID: <YKVn69o1UizH0kJD@casper.infradead.org>
Date:   Wed, 19 May 2021 20:32:59 +0100
From:   Matthew Wilcox <willy@...radead.org>
To:     Aaron Tomlin <atomlin@...hat.com>
Cc:     linux-mm@...ck.org, akpm@...ux-foundation.org, vbabka@...e.cz,
        mhocko@...e.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] mm/page_alloc: bail out on fatal signal during
 reclaim/compaction retry attempt

On Wed, May 19, 2021 at 08:23:21PM +0100, Aaron Tomlin wrote:
> +++ b/mm/page_alloc.c
> @@ -4252,6 +4252,9 @@ should_compact_retry(struct alloc_context *ac, int order, int alloc_flags,
>  	if (!order)
>  		return false;
>  
> +	if (fatal_signal_pending(current))
> +		goto out;

I think 'goto out' will be confusing.  It'll output a tracepoint, which
isn't going to record that a fatal signal is pending, so it'll cause
some head scratching for someone looking through the traces.  I
think we should just return false here and skip the tracepoint.

But I'd defer to someone like Vlastimil or Michal who know this code far
better than I do.