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Wed, 31 Jan 2024 14:26:27 -0800 (PST) MIME-Version: 1.0 References: <20240131172027.10f64405@gandalf.local.home> In-Reply-To: <20240131172027.10f64405@gandalf.local.home> From: Yosry Ahmed Date: Wed, 31 Jan 2024 14:25:49 -0800 Message-ID: Subject: Re: Do we still need SLAB_MEM_SPREAD (and possibly others)? To: Steven Rostedt Cc: LKML , linux-mm@kvack.org, Andrew Morton , Linus Torvalds , Vlastimil Babka , Kees Cook , Christoph Lameter , David Rientjes , Hyeonggon Yoo <42.hyeyoo@gmail.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 176E880018 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: rp6wnrem55don3cmo75gejjp4fnszxo4 X-HE-Tag: 1706739988-743240 X-HE-Meta: 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 fUaTX/Og 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Jan 31, 2024 at 2:20=E2=80=AFPM Steven Rostedt wrote: > > I was looking into moving eventfs_inode into a slab, and after cutting an= d > pasting the tracefs allocator: > > tracefs_inode_cachep =3D kmem_cache_create("tracefs_inode_cache", > sizeof(struct tracefs_in= ode), > 0, (SLAB_RECLAIM_ACCOUNT= | > SLAB_MEM_SPREAD| > SLAB_ACCOUNT), > init_once); > > I figured I should know what those slab flags mean. I also looked at what > others in fs use for their slabs. The above is rather common (which I > probably just copied from another file system), but I wanted to know what > they are for. > > When I got to SLAB_MEM_SPREAD, I found that it's a common flag and there'= s > a lot of caches that just set that and nothing else. > > But I couldn't find how it was used. > > Then I found this commit: > > 16a1d968358a ("mm/slab: remove mm/slab.c and slab_def.h") > > Which I think removed the only use case of SLAB_MEM_SPREAD. > > $ git grep SLAB_MEM_SPREAD mm > mm/slab.h: SLAB_MEM_SPREAD | \ > > That's all I find in the mm directory. > > Is it obsolete now? Can we delete it? Maybe there's other SLAB_* flags th= at > are no longer used. I don't know, I haven't audited them. Perhaps cpuset_do_slab_mem_spread() as well.