linux-kernel - Re: [PATCH v17 17/21] mm/lru: replace pgdat lru

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Message-ID: <cb49a573-8d24-d289-199d-8058cd79b89b@linux.alibaba.com>
Date:   Wed, 29 Jul 2020 08:48:00 +0800
From:   Alex Shi <alex.shi@...ux.alibaba.com>
To:     Alexander Duyck <alexander.duyck@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Tejun Heo <tj@...nel.org>, Hugh Dickins <hughd@...gle.com>,
        Konstantin Khlebnikov <khlebnikov@...dex-team.ru>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        Matthew Wilcox <willy@...radead.org>,
        Johannes Weiner <hannes@...xchg.org>,
        kbuild test robot <lkp@...el.com>,
        linux-mm <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>, cgroups@...r.kernel.org,
        Shakeel Butt <shakeelb@...gle.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Wei Yang <richard.weiyang@...il.com>,
        "Kirill A. Shutemov" <kirill@...temov.name>,
        Rong Chen <rong.a.chen@...el.com>,
        Michal Hocko <mhocko@...nel.org>,
        Vladimir Davydov <vdavydov.dev@...il.com>
Subject: Re: [PATCH v17 17/21] mm/lru: replace pgdat lru_lock with lruvec lock



在 2020/7/28 下午11:55, Alexander Duyck 写道:
>>  /*
>> @@ -511,11 +511,11 @@ static bool compact_lock_irqsave(spinlock_t *lock, unsigned long *flags,
>>   *             scheduled)
>>   */
>>  static bool compact_unlock_should_abort(spinlock_t *lock,
>> -               unsigned long flags, bool *locked, struct compact_control *cc)
>> +               unsigned long flags, void **locked, struct compact_control *cc)
> Instead of passing both a void pointer and the lock why not just pass
> the pointer to the lock pointer? You could combine lock and locked
> into a single argument and save yourself some extra effort.
> 

the passed locked pointer could be rewrite in the func, that is unacceptable if it is a lock which could
be used other place.

And it is alreay dangerous to NULL a local pointer. In fact, I perfer the orignal verion, not so smart
but rebust enough for future changes, right?

Thanks
Alex


>>  {
>>         if (*locked) {
>>                 spin_unlock_irqrestore(lock, flags);
>> -               *locked = false;
>> +               *locked = NULL;
>>         }
>>
>>         if (fatal_signal_pending(current)) {