From: Matthew Wilcox <willy@infradead.org>
To: zhong jiang <zhongjiang@huawei.com>
Cc: akpm@linux-foundation.org, vbabka@suse.cz, mhocko@kernel.org,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] mm: Unsigned 'nr_pages' always larger than zero
Date: Wed, 4 Sep 2019 20:12:52 -0700 [thread overview]
Message-ID: <20190905031252.GN29434@bombadil.infradead.org> (raw)
In-Reply-To: <1567649871-60594-1-git-send-email-zhongjiang@huawei.com>
On Thu, Sep 05, 2019 at 10:17:51AM +0800, zhong jiang wrote:
> With the help of unsigned_lesser_than_zero.cocci. Unsigned 'nr_pages'
> compare with zero. And __gup_longterm_locked pass an long local variant
> 'rc' to check_and_migrate_cma_pages. Hence it is nicer to change the
> parameter to long to fix the issue.
I think this patch is right, but I have concerns about this cocci grep.
The code says:
if ((nr_pages > 0) && migrate_allow) {
There's nothing wrong with this (... other than the fact that nr_pages might
happen to be a negative errno). nr_pages might be 0, and this would be
exactly the right test for that situation. I suppose some might argue
that this should be != 0 instead of > 0, but it depends on the situation
which one would read better.
So please don't blindly make these changes; you're right this time.
next prev parent reply other threads:[~2019-09-05 3:13 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-05 2:17 [PATCH v2] mm: Unsigned 'nr_pages' always larger than zero zhong jiang
2019-09-05 3:12 ` Matthew Wilcox [this message]
2019-09-05 6:09 ` zhong jiang
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