linux-kernel - Re: [PATCH] mm: add ZONE_DEVICE statistics to smaps

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: <1c6d61ef-2331-e517-d0d8-d4eefea8b18a@intel.com>
Date:   Tue, 15 Nov 2016 16:15:05 -0800
From:   Dave Hansen <dave.hansen@...el.com>
To:     Dan Williams <dan.j.williams@...el.com>, akpm@...ux-foundation.org
Cc:     linux-nvdimm@...ts.01.org, Christoph Hellwig <hch@....de>,
        linux-kernel@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH] mm: add ZONE_DEVICE statistics to smaps

On 11/10/2016 02:11 PM, Dan Williams wrote:
> @@ -774,6 +778,8 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
>  		   "ShmemPmdMapped: %8lu kB\n"
>  		   "Shared_Hugetlb: %8lu kB\n"
>  		   "Private_Hugetlb: %7lu kB\n"
> +		   "Device:         %8lu kB\n"
> +		   "DeviceHugePages: %7lu kB\n"
>  		   "Swap:           %8lu kB\n"
>  		   "SwapPss:        %8lu kB\n"
>  		   "KernelPageSize: %8lu kB\n"

So, a couple of nits...

smaps is getting a bit big, and the fields that get added in this patch
are going to be pretty infrequently used.  Is it OK if smaps grows
forever, even if most of them items are "0 kB"?

IOW, Could we make it output Device* only for DAX VMAs?  All the parsers
have to handle that field being there or not (for old kernels).

The other thing missing for DAX is the page size.  DAX mappings support
mixed page sizes, so MMUPageSize in this context is pretty worthless.
What will we do in here for 1GB DAX pages?