linux-kernel - Re: [PATCH v2] mm, zone_device: replace {get, put}_zone_device

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]

Date:   Sat, 29 Apr 2017 16:18:38 +0200
From:   Ingo Molnar <mingo@...nel.org>
To:     Dan Williams <dan.j.williams@...el.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        Jérôme Glisse <jglisse@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Logan Gunthorpe <logang@...tatee.com>,
        Kirill Shutemov <kirill.shutemov@...ux.intel.com>
Subject: Re: [PATCH v2] mm, zone_device: replace {get,
 put}_zone_device_page() with a single reference


* Dan Williams <dan.j.williams@...el.com> wrote:

> Kirill points out that the calls to {get,put}_dev_pagemap() can be
> removed from the mm fast path if we take a single get_dev_pagemap()
> reference to signify that the page is alive and use the final put of the
> page to drop that reference.
> 
> This does require some care to make sure that any waits for the
> percpu_ref to drop to zero occur *after* devm_memremap_page_release(),
> since it now maintains its own elevated reference.
> 
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Jérôme Glisse <jglisse@...hat.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Reviewed-by: Logan Gunthorpe <logang@...tatee.com>
> Suggested-by: Kirill Shutemov <kirill.shutemov@...ux.intel.com>
> Tested-by: Kirill Shutemov <kirill.shutemov@...ux.intel.com>
> Signed-off-by: Dan Williams <dan.j.williams@...el.com>

This changelog is lacking an explanation about how this solves the crashes you 
were seeing.

Thanks,

	Ingo