linux-kernel - Re: [PATCH v3 07/35] mm/slab: introduce SLAB_NO_OBJ_EXT to avoid obj

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: <CAJuCfpGBCNsvK35Bq8666cJeZ3Hwfwj6mDJ6M5Wjg7oZi8xd0g@mail.gmail.com>
Date: Fri, 16 Feb 2024 18:41:46 +0000
From: Suren Baghdasaryan <surenb@...gle.com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: Kent Overstreet <kent.overstreet@...ux.dev>, akpm@...ux-foundation.org, mhocko@...e.com, 
	hannes@...xchg.org, roman.gushchin@...ux.dev, mgorman@...e.de, 
	dave@...olabs.net, willy@...radead.org, liam.howlett@...cle.com, 
	corbet@....net, void@...ifault.com, peterz@...radead.org, 
	juri.lelli@...hat.com, catalin.marinas@....com, will@...nel.org, 
	arnd@...db.de, tglx@...utronix.de, mingo@...hat.com, 
	dave.hansen@...ux.intel.com, x86@...nel.org, peterx@...hat.com, 
	david@...hat.com, axboe@...nel.dk, mcgrof@...nel.org, masahiroy@...nel.org, 
	nathan@...nel.org, dennis@...nel.org, tj@...nel.org, muchun.song@...ux.dev, 
	rppt@...nel.org, paulmck@...nel.org, pasha.tatashin@...een.com, 
	yosryahmed@...gle.com, yuzhao@...gle.com, dhowells@...hat.com, 
	hughd@...gle.com, andreyknvl@...il.com, keescook@...omium.org, 
	ndesaulniers@...gle.com, vvvvvv@...gle.com, gregkh@...uxfoundation.org, 
	ebiggers@...gle.com, ytcoode@...il.com, vincent.guittot@...aro.org, 
	dietmar.eggemann@....com, rostedt@...dmis.org, bsegall@...gle.com, 
	bristot@...hat.com, vschneid@...hat.com, cl@...ux.com, penberg@...nel.org, 
	iamjoonsoo.kim@....com, 42.hyeyoo@...il.com, glider@...gle.com, 
	elver@...gle.com, dvyukov@...gle.com, shakeelb@...gle.com, 
	songmuchun@...edance.com, jbaron@...mai.com, rientjes@...gle.com, 
	minchan@...gle.com, kaleshsingh@...gle.com, kernel-team@...roid.com, 
	linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org, 
	iommu@...ts.linux.dev, linux-arch@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, linux-mm@...ck.org, 
	linux-modules@...r.kernel.org, kasan-dev@...glegroups.com, 
	cgroups@...r.kernel.org
Subject: Re: [PATCH v3 07/35] mm/slab: introduce SLAB_NO_OBJ_EXT to avoid
 obj_ext creation

On Thu, Feb 15, 2024 at 10:10 PM Suren Baghdasaryan <surenb@...gle.com> wrote:
>
> On Thu, Feb 15, 2024 at 1:50 PM Vlastimil Babka <vbabka@...e.cz> wrote:
> >
> > On 2/15/24 22:37, Kent Overstreet wrote:
> > > On Thu, Feb 15, 2024 at 10:31:06PM +0100, Vlastimil Babka wrote:
> > >> On 2/12/24 22:38, Suren Baghdasaryan wrote:
> > >> > Slab extension objects can't be allocated before slab infrastructure is
> > >> > initialized. Some caches, like kmem_cache and kmem_cache_node, are created
> > >> > before slab infrastructure is initialized. Objects from these caches can't
> > >> > have extension objects. Introduce SLAB_NO_OBJ_EXT slab flag to mark these
> > >> > caches and avoid creating extensions for objects allocated from these
> > >> > slabs.
> > >> >
> > >> > Signed-off-by: Suren Baghdasaryan <surenb@...gle.com>
> > >> > ---
> > >> >  include/linux/slab.h | 7 +++++++
> > >> >  mm/slub.c            | 5 +++--
> > >> >  2 files changed, 10 insertions(+), 2 deletions(-)
> > >> >
> > >> > diff --git a/include/linux/slab.h b/include/linux/slab.h
> > >> > index b5f5ee8308d0..3ac2fc830f0f 100644
> > >> > --- a/include/linux/slab.h
> > >> > +++ b/include/linux/slab.h
> > >> > @@ -164,6 +164,13 @@
> > >> >  #endif
> > >> >  #define SLAB_TEMPORARY            SLAB_RECLAIM_ACCOUNT    /* Objects are short-lived */
> > >> >
> > >> > +#ifdef CONFIG_SLAB_OBJ_EXT
> > >> > +/* Slab created using create_boot_cache */
> > >> > +#define SLAB_NO_OBJ_EXT         ((slab_flags_t __force)0x20000000U)
> > >>
> > >> There's
> > >>    #define SLAB_SKIP_KFENCE        ((slab_flags_t __force)0x20000000U)
> > >> already, so need some other one?
>
> Indeed. I somehow missed it. Thanks for noticing, will fix this in the
> next version.

Apparently the only unused slab flag is 0x00000200U, all others seem
to be taken. I'll use it if there are no objections.

>
> > >
> > > What's up with the order of flags in that file? They don't seem to
> > > follow any particular ordering.
> >
> > Seems mostly in increasing order, except commit 4fd0b46e89879 broke it for
> > SLAB_RECLAIM_ACCOUNT?
> >
> > > Seems like some cleanup is in order, but any history/context we should
> > > know first?
> >
> > Yeah noted, but no need to sidetrack you.