linux-kernel - Re: Regression - locking (all from 2.6.28)

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: <1236358369.10626.58.camel@nimitz>
Date:	Fri, 06 Mar 2009 08:52:49 -0800
From:	Dave Hansen <dave@...ux.vnet.ibm.com>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	jan sonnek <ha2nny@...il.com>, linux-kernel@...r.kernel.org,
	viro@...iv.linux.org.uk, Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Andy Whitcroft <apw@...dowen.org>
Subject: Re: Regression - locking (all from 2.6.28)

On Fri, 2009-03-06 at 16:40 +0000, Catalin Marinas wrote:
> It seems that node_start_pfn() isn't present on all the architectures. I
> ended up with something like below:
> 
> +	/* struct page scanning for each node */
> +	for_each_online_node(i) {
> +		pg_data_t *pgdat = NODE_DATA(i);
> +		unsigned long start_pfn = pgdat->node_start_pfn;
> +		unsigned long end_pfn = start_pfn +
> +			pgdat->node_spanned_pages - 1;
> +		unsigned long pfn;
> +
> +		for (pfn = start_pfn; pfn < end_pfn; pfn++) {
> +			struct page *page;
> +
> +			if (!pfn_valid(pfn))
> +				continue;
> +			page = pfn_to_page(pfn);
> +			/* only scan if page is in use */
> +			if (page_count(page) == 0)
> +				continue;
> +			scan_block(page, page + 1, NULL);
> +		}
> +	}

What does scan_block() actually scan?  Is that second argument
inclusive?

I think you will miss scanning the contents of the last 'struct page' if
you do it this way because of the -1 you do to end_pfn.

> Are the pgdat->node_start_pfn and pgdat->node_spanned_pages always
> valid? Thanks.

The variables themselves?  I'm sure there's a window in early boot where
they aren't valid, but other than that they should be OK unless you're
int the middle of a hotplug operation.

See pgdat_resize_(un)lock() in include/linux/memory_hotplug.h.

-- Dave

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/