linux-kernel - Re: [PATCH v2 2/7] mm/swapfile.c: Replace some #ifdef with IS

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Message-ID: <87wotr6dll.fsf@yhuang-dev.intel.com>
Date:   Thu, 19 Jul 2018 12:42:14 +0800
From:   "Huang\, Ying" <ying.huang@...el.com>
To:     Dave Hansen <dave.hansen@...ux.intel.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, <linux-mm@...ck.org>,
        <linux-kernel@...r.kernel.org>, Michal Hocko <mhocko@...e.com>,
        "Johannes Weiner" <hannes@...xchg.org>,
        Shaohua Li <shli@...nel.org>, Hugh Dickins <hughd@...gle.com>,
        Minchan Kim <minchan@...nel.org>,
        Rik van Riel <riel@...hat.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v2 2/7] mm/swapfile.c: Replace some #ifdef with IS_ENABLED()

Dave Hansen <dave.hansen@...ux.intel.com> writes:

> On 07/17/2018 08:25 PM, Huang, Ying wrote:
>>> Seriously, though, does it hurt us to add a comment or two to say
>>> something like:
>>>
>>> 	/*
>>> 	 * Should not even be attempting cluster allocations when
>>> 	 * huge page swap is disabled.  Warn and fail the allocation.
>>> 	 */
>>> 	if (!IS_ENABLED(CONFIG_THP_SWAP)) {
>>> 		VM_WARN_ON_ONCE(1);
>>> 		return 0;
>>> 	}
>> I totally agree with you that we should add more comments for THP swap
>> to improve the code readability.  As for this specific case,
>> VM_WARN_ON_ONCE() here is just to capture some programming error during
>> development.  Do we really need comments here?
>
> If it's code in mainline, we need to know what it is doing.
>
> If it's not useful to have in mainline, then let's remove it.

OK.  Will add the comments.

Best Regards,
Huang, Ying