From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH 03/33] mm: slub: add knowledge of reserve pages From: Peter Zijlstra In-Reply-To: <200710312225.07249.nickpiggin@yahoo.com.au> References: <20071030160401.296770000@chello.nl> <200710312146.03351.nickpiggin@yahoo.com.au> <1193833072.27652.167.camel@twins> <200710312225.07249.nickpiggin@yahoo.com.au> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-1JONk1CHaR7M71QTq2Rs" Date: Wed, 31 Oct 2007 13:54:18 +0100 Message-Id: <1193835258.27652.199.camel@twins> Mime-Version: 1.0 Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Linus Torvalds , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, trond.myklebust@fys.uio.no List-ID: --=-1JONk1CHaR7M71QTq2Rs Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Wed, 2007-10-31 at 22:25 +1100, Nick Piggin wrote: > On Wednesday 31 October 2007 23:17, Peter Zijlstra wrote: > > On Wed, 2007-10-31 at 21:46 +1100, Nick Piggin wrote: >=20 > > > And I'd prevent these ones from doing so. > > > > > > Without keeping track of "reserve" pages, which doesn't feel > > > too clean. > > > > The problem with that is that once a slab was allocated with the right > > allocation context, anybody can get objects from these slabs. >=20 > [snip] >=20 > I understand that. >=20 >=20 > > So we either reserve a page per object, which for 32 byte objects is a > > large waste, or we stop anybody who doesn't have the right permissions > > from obtaining objects. I took the latter approach. >=20 > What I'm saying is that the slab allocator slowpath should always > just check watermarks against the current task. Instead of this > ->reserve stuff. So what you say is to allocate a slab every time we take the slow path, even when we already have one? That sounds rather sub-optimal. --=-1JONk1CHaR7M71QTq2Rs Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBHKHr6XA2jU0ANEf4RAm9gAJ9xM3miH4H0KzYn+MEPjt6I1zY3swCdEN3/ FchO1Oe5ngFrcknUFRAg2jQ= =2VhI -----END PGP SIGNATURE----- --=-1JONk1CHaR7M71QTq2Rs-- -- 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