From: Artemy Kovalyov <artemyko@mellanox.com>
To: Ira Weiny <ira.weiny@intel.com>,
"john.hubbard@gmail.com" <john.hubbard@gmail.com>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
LKML <linux-kernel@vger.kernel.org>,
"John Hubbard" <jhubbard@nvidia.com>,
Jason Gunthorpe <jgg@ziepe.ca>,
Doug Ledford <dledford@redhat.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
Subject: Re: [PATCH v2] RDMA/umem: minor bug fix and cleanup in error handling paths
Date: Sun, 3 Mar 2019 11:52:41 +0200 [thread overview]
Message-ID: <2404c962-8f6d-1f6d-0055-eb82864ca7fc@mellanox.com> (raw)
In-Reply-To: <20190302194402.GA24732@iweiny-DESK2.sc.intel.com>
On 02/03/2019 21:44, Ira Weiny wrote:
>
> On Sat, Mar 02, 2019 at 12:24:35PM -0800, john.hubbard@gmail.com wrote:
>> From: John Hubbard <jhubbard@nvidia.com>
>>
>> ...
>> 3. Dead code removal: the check for (user_virt & ~page_mask)
>> is checking for a condition that can never happen,
>> because earlier:
>>
>> user_virt = user_virt & page_mask;
>>
>> ...so, remove that entire phrase.
>>
>>
>> bcnt -= min_t(size_t, npages << PAGE_SHIFT, bcnt);
>> mutex_lock(&umem_odp->umem_mutex);
>> for (j = 0; j < npages; j++, user_virt += PAGE_SIZE) {
>> - if (user_virt & ~page_mask) {
>> - p += PAGE_SIZE;
>> - if (page_to_phys(local_page_list[j]) != p) {
>> - ret = -EFAULT;
>> - break;
>> - }
>> - put_page(local_page_list[j]);
>> - continue;
>> - }
>> -
>
> I think this is trying to account for compound pages. (ie page_mask could
> represent more than PAGE_SIZE which is what user_virt is being incrimented by.)
> But putting the page in that case seems to be the wrong thing to do?
>
> Yes this was added by Artemy[1] now cc'ed.
Right, this is for huge pages, please keep it.
put_page() needed to decrement refcount of the head page.
next prev parent reply other threads:[~2019-03-03 9:53 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-03-02 3:27 [PATCH 0/1] " john.hubbard
2019-03-02 3:27 ` [PATCH] " john.hubbard
2019-03-02 16:03 ` kbuild test robot
2019-03-02 16:14 ` kbuild test robot
2019-03-02 20:24 ` [PATCH v2] " john.hubbard
2019-03-02 19:44 ` Ira Weiny
2019-03-03 9:52 ` Artemy Kovalyov [this message]
2019-03-03 16:55 ` Ira Weiny
2019-03-04 23:11 ` John Hubbard
2019-03-04 20:13 ` Ira Weiny
2019-03-05 20:10 ` John Hubbard
2019-03-04 23:36 ` John Hubbard
2019-03-05 0:53 ` Jason Gunthorpe
2019-03-03 22:37 ` John Hubbard
2019-03-04 6:44 ` Leon Romanovsky
2019-03-06 1:02 ` Artemy Kovalyov
2019-03-06 1:32 ` Jason Gunthorpe
2019-03-06 1:34 ` John Hubbard
2019-03-06 1:37 ` John Hubbard
2019-03-06 1:51 ` Jason Gunthorpe
2019-03-06 2:04 ` John Hubbard
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