From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Tue, 28 Feb 2006 12:32:04 +0000 (GMT) From: Hugh Dickins Subject: Re: vDSO vs. mm : problems with ppc vdso In-Reply-To: <440424CA.5070206@yahoo.com.au> Message-ID: References: <1141105154.3767.27.camel@localhost.localdomain> <20060227215416.2bfc1e18.akpm@osdl.org> <1141106896.3767.34.camel@localhost.localdomain> <20060227222055.4d877f16.akpm@osdl.org> <1141108220.3767.43.camel@localhost.localdomain> <440424CA.5070206@yahoo.com.au> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Benjamin Herrenschmidt , Andrew Morton , linux-mm@kvack.org, paulus@samba.org, davem@davemloft.net List-ID: On Tue, 28 Feb 2006, Nick Piggin wrote: > > You should be OK. VM_RESERVED itself is something of an anachronism > these days. If you're not getting your page from the page allocator > then you'll want to make sure each of their count, and mapcount is > reset before allowing them to be mapped. Yes, it's fine that VM_RESERVED isn't set on it. But I don't understand your remarks about count and mapcount at all: perhaps you meant to say something else? If I ignore what you actually said, and think of what problems there might be in that area, then yes, if the pages come from kernel memory (they do) rather than page allocator, we'd better make sure page_count starts above 0, so it doesn't go down to zero on last free from userspace: and indeed, Ben's vdso_init does a get_page on each to ensure that. Hugh -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org