From: Andrew Morton <akpm@linux-foundation.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: zhong jiang <zhongjiang@huawei.com>,
mhocko@kernel.org, anshuman.khandual@arm.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Ira Weiny <ira.weiny@intel.com>,
"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 12:01:59 -0700 [thread overview]
Message-ID: <20190904120159.d4026b573f419838d77e991d@linux-foundation.org> (raw)
In-Reply-To: <5505fa16-117e-8890-0f48-38555a61a036@suse.cz>
On Wed, 4 Sep 2019 13:24:58 +0200 Vlastimil Babka <vbabka@suse.cz> 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).
>
> > Signed-off-by: zhong jiang <zhongjiang@huawei.com>
>
> Fixes: 932f4a630a69 ("mm/gup: replace get_user_pages_longterm() with FOLL_LONGTERM")
>
> (which changed long to unsigned long)
>
> AFAICS... stable shouldn't be needed as the only "risk" is that we goto
> check_again even when we fail, which should be harmless.
>
Really? If nr_pages gets a value of -EFAULT from the
__get_user_pages_locked() call, check_and_migrate_cma_pages() will go
berzerk?
And does __get_user_pages_locked() correctly handle a -ve errno
returned by __get_user_pages()? It's hard to see how...
next prev parent reply other threads:[~2019-09-04 19:02 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
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 [this message]
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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