linux-kernel - Re: [PATCH 1/1] infiniband/mm: convert put_page() to put_user

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20190523173222.GH12145@mellanox.com>
Date:   Thu, 23 May 2019 17:32:26 +0000
From:   Jason Gunthorpe <jgg@...lanox.com>
To:     Ira Weiny <ira.weiny@...el.com>
CC:     "john.hubbard@...il.com" <john.hubbard@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        LKML <linux-kernel@...r.kernel.org>,
        "linux-rdma@...r.kernel.org" <linux-rdma@...r.kernel.org>,
        "linux-fsdevel@...r.kernel.org" <linux-fsdevel@...r.kernel.org>,
        John Hubbard <jhubbard@...dia.com>,
        Doug Ledford <dledford@...hat.com>,
        Mike Marciniszyn <mike.marciniszyn@...el.com>,
        Dennis Dalessandro <dennis.dalessandro@...el.com>,
        Christian Benvenuti <benve@...co.com>, Jan Kara <jack@...e.cz>
Subject: Re: [PATCH 1/1] infiniband/mm: convert put_page() to put_user_page*()

On Thu, May 23, 2019 at 10:28:52AM -0700, Ira Weiny wrote:
> >  
> > @@ -686,8 +686,8 @@ int ib_umem_odp_map_dma_pages(struct ib_umem_odp *umem_odp, u64 user_virt,
> >  			 * ib_umem_odp_map_dma_single_page().
> >  			 */
> >  			if (npages - (j + 1) > 0)
> > -				release_pages(&local_page_list[j+1],
> > -					      npages - (j + 1));
> > +				put_user_pages(&local_page_list[j+1],
> > +					       npages - (j + 1));
> 
> I don't know if we discussed this before but it looks like the use of
> release_pages() was not entirely correct (or at least not necessary) here.  So
> I think this is ok.

Oh? John switched it from a put_pages loop to release_pages() here:

commit 75a3e6a3c129cddcc683538d8702c6ef998ec589
Author: John Hubbard <jhubbard@...dia.com>
Date:   Mon Mar 4 11:46:45 2019 -0800

    RDMA/umem: minor bug fix in error handling path
    
    1. Bug fix: fix an off by one error in the code that cleans up if it fails
       to dma-map a page, after having done a get_user_pages_remote() on a
       range of pages.
    
    2. Refinement: for that same cleanup code, release_pages() is better than
       put_page() in a loop.
    

And now we are going to back something called put_pages() that
implements the same for loop the above removed?

Seems like we are going in circles?? John?

Jason