From: zhong jiang <zhongjiang@huawei.com>
To: Matthew Wilcox <willy@infradead.org>
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: Thu, 5 Sep 2019 14:09:25 +0800 [thread overview]
Message-ID: <5D70A695.60706@huawei.com> (raw)
In-Reply-To: <20190905031252.GN29434@bombadil.infradead.org>
On 2019/9/5 11:12, Matthew Wilcox wrote:
> 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.
Thanks for your affirmation. but Andrew come up with anther fix, using an local long variant
to store the nr_pages. which one do you prefer ?
Thanks,
zhong jiang
prev parent reply other threads:[~2019-09-05 6:09 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
2019-09-05 6:09 ` zhong jiang [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5D70A695.60706@huawei.com \
--to=zhongjiang@huawei.com \
--cc=akpm@linux-foundation.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mm@kvack.org \
--cc=mhocko@kernel.org \
--cc=vbabka@suse.cz \
--cc=willy@infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).