From: Matthew Wilcox <willy@infradead.org>
To: "Weiny, Ira" <ira.weiny@intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>,
zhong jiang <zhongjiang@huawei.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"mhocko@kernel.org" <mhocko@kernel.org>,
"anshuman.khandual@arm.com" <anshuman.khandual@arm.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
Subject: Re: [PATCH] mm: Unsigned 'nr_pages' always larger than zero
Date: Wed, 4 Sep 2019 11:39:58 -0700 [thread overview]
Message-ID: <20190904183958.GM29434@bombadil.infradead.org> (raw)
In-Reply-To: <2807E5FD2F6FDA4886F6618EAC48510E898E9559@CRSMSX101.amr.corp.intel.com>
On Wed, Sep 04, 2019 at 06:25:19PM +0000, Weiny, Ira wrote:
> > On 9/4/19 12:26 PM, zhong jiang wrote:
> > > With the help of unsigned_lesser_than_zero.cocci. Unsigned 'nr_pages"'
> > > compare with zero. And __get_user_pages_locked will return an long
> > value.
> > > Hence, Convert the long to compare with zero is feasible.
> >
> > It would be nicer if the parameter nr_pages was long again instead of
> > unsigned long (note there are two variants of the function, so both should be
> > changed).
>
> Why? What does it mean for nr_pages to be negative? The check below seems valid. Unsigned can be 0 so the check can fail. IOW Checking unsigned > 0 seems ok.
>
> What am I missing?
__get_user_pages can return a negative errno.
next prev parent reply other threads:[~2019-09-04 18:40 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-04 10:26 [PATCH] mm: Unsigned 'nr_pages' always larger than zero zhong jiang
2019-09-04 11:24 ` Vlastimil Babka
2019-09-04 18:25 ` Weiny, Ira
2019-09-04 18:39 ` Matthew Wilcox [this message]
2019-09-04 18:48 ` Andrew Morton
2019-09-04 20:20 ` Weiny, Ira
2019-09-04 20:40 ` Vlastimil Babka
2019-09-05 6:18 ` zhong jiang
2019-09-05 7:19 ` Vlastimil Babka
2019-09-05 6:19 ` John Hubbard
2019-10-16 9:07 ` zhong jiang
2019-10-17 0:49 ` Andrew Morton
2019-10-17 1:38 ` zhong jiang
2019-09-04 19:01 ` Andrew Morton
2019-09-04 20:44 ` Vlastimil Babka
2019-09-05 2:05 ` zhong jiang
2019-10-17 3:19 zhong jiang
2019-10-17 18:01 ` Ira Weiny
2019-10-18 2:01 ` zhong jiang
2019-10-17 20:42 ` John Hubbard
2019-10-18 2:15 ` zhong jiang
2019-10-18 14:00 ` zhong jiang
2019-10-18 16:07 ` Alexander Duyck
2019-10-21 15:11 ` zhong jiang
2019-10-21 12:57 ` Vlastimil Babka
2019-10-21 13:47 ` zhong jiang
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