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AJvYcCUSZj6LiBh5l+mhelluMdAjnkqciaHAJICN41Gbn/cnngXLdVgnv5RT0YNPCCJeAsczEontpJldr7YrKbFYDmr9Y0s= X-Gm-Message-State: AOJu0Yzuu2ptg2Nhp88Zr+2sWxsUsnvxI53KcrI6cCX2gYc4KyX+yZt6 qiYdTgPhKCyCUb4QEZcfTWPArM4typmxX2w3XfhFFz5N2nQmFzsgjzZMbOA8EKwnxSVkxVsmGeK Hkq5FQ0FzNq+ZW/+SqLmKN5KczbraRP50iTpX X-Google-Smtp-Source: AGHT+IFcIoxxZ/at1Ut37e+obqddPjXFDoTfSw2W9xlVFGkbEDUuUmXcmdD9+Fz3EgwVz//7/lLpGbCXr+gCQA4ZbLI= X-Received: by 2002:a25:8241:0:b0:dcc:623d:e475 with SMTP id d1-20020a258241000000b00dcc623de475mr508725ybn.30.1707782975978; Mon, 12 Feb 2024 16:09:35 -0800 (PST) MIME-Version: 1.0 References: <20240212213922.783301-1-surenb@google.com> <20240212213922.783301-35-surenb@google.com> <202402121448.AF0AA8E@keescook> In-Reply-To: <202402121448.AF0AA8E@keescook> From: Suren Baghdasaryan Date: Mon, 12 Feb 2024 16:09:21 -0800 Message-ID: Subject: Re: [PATCH v3 34/35] codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations To: Kees Cook Cc: akpm@linux-foundation.org, kent.overstreet@linux.dev, mhocko@suse.com, vbabka@suse.cz, hannes@cmpxchg.org, roman.gushchin@linux.dev, mgorman@suse.de, dave@stgolabs.net, willy@infradead.org, liam.howlett@oracle.com, corbet@lwn.net, void@manifault.com, peterz@infradead.org, juri.lelli@redhat.com, catalin.marinas@arm.com, will@kernel.org, arnd@arndb.de, tglx@linutronix.de, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, peterx@redhat.com, david@redhat.com, axboe@kernel.dk, mcgrof@kernel.org, masahiroy@kernel.org, nathan@kernel.org, dennis@kernel.org, tj@kernel.org, muchun.song@linux.dev, rppt@kernel.org, paulmck@kernel.org, pasha.tatashin@soleen.com, yosryahmed@google.com, yuzhao@google.com, dhowells@redhat.com, hughd@google.com, andreyknvl@gmail.com, ndesaulniers@google.com, vvvvvv@google.com, gregkh@linuxfoundation.org, ebiggers@google.com, ytcoode@gmail.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, bristot@redhat.com, vschneid@redhat.com, cl@linux.com, penberg@kernel.org, iamjoonsoo.kim@lge.com, 42.hyeyoo@gmail.com, glider@google.com, elver@google.com, dvyukov@google.com, shakeelb@google.com, songmuchun@bytedance.com, jbaron@akamai.com, rientjes@google.com, minchan@google.com, kaleshsingh@google.com, kernel-team@android.com, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, iommu@lists.linux.dev, linux-arch@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-modules@vger.kernel.org, kasan-dev@googlegroups.com, cgroups@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Rspamd-Queue-Id: 393CD4000A X-Rspam-User: X-Rspamd-Server: rspam11 X-Stat-Signature: 14zwigrsyoaikd73f5tg5hms77w4gkmo X-HE-Tag: 1707782977-567240 X-HE-Meta: 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 qVF79wRE TK5mefWxeIOa29esofasvLzdqK+SmvF3RqJtL7uRg6ebHjzXEoyjxR+4yy68cUYcEBnnxNOxqAwTeiTDlWCHYyTGoHtxW0Qm3xKx4vYikHyu0QRUNf6qWgTDO3lXGAsH2IUFBxuyI5O0rsdpTIk5bsiwvaPT6OOeAPiEfWuTEcV4Xd64mFnHIT5hrTzeNI3lqBWejVw03UQrpFlL1Ays24sdieeP6QEw52nKwJ8kJQucRn2crFidesvvdDpjf2mSSkmc7u4Nt2pz4YK7vsXVLqNZPZZUSo9HN5YRko/xH7z+N67TxtRaY002nsRgxdxa+qAheeIyE3mcQvfvWDcGIAUAXhYvcArurv4OyqD5j1ZSYcw9o6Mi8ckwmEuXnfHw1/Fq7z1+794KP98SHIbivQfQbmc5HNatfQtvNuh1ZYuBnSaA= 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 Mon, Feb 12, 2024 at 2:49=E2=80=AFPM Kees Cook w= rote: > > On Mon, Feb 12, 2024 at 01:39:20PM -0800, Suren Baghdasaryan wrote: > > If slabobj_ext vector allocation for a slab object fails and later on i= t > > succeeds for another object in the same slab, the slabobj_ext for the > > original object will be NULL and will be flagged in case when > > CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled. > > Mark failed slabobj_ext vector allocations using a new objext_flags fla= g > > stored in the lower bits of slab->obj_exts. When new allocation succeed= s > > it marks all tag references in the same slabobj_ext vector as empty to > > avoid warnings implemented by CONFIG_MEM_ALLOC_PROFILING_DEBUG checks. > > > > Signed-off-by: Suren Baghdasaryan > > --- > > include/linux/memcontrol.h | 4 +++- > > mm/slab.h | 25 +++++++++++++++++++++++++ > > mm/slab_common.c | 22 +++++++++++++++------- > > 3 files changed, 43 insertions(+), 8 deletions(-) > > > > diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h > > index 2b010316016c..f95241ca9052 100644 > > --- a/include/linux/memcontrol.h > > +++ b/include/linux/memcontrol.h > > @@ -365,8 +365,10 @@ enum page_memcg_data_flags { > > #endif /* CONFIG_MEMCG */ > > > > enum objext_flags { > > + /* slabobj_ext vector failed to allocate */ > > + OBJEXTS_ALLOC_FAIL =3D __FIRST_OBJEXT_FLAG, > > /* the next bit after the last actual flag */ > > - __NR_OBJEXTS_FLAGS =3D __FIRST_OBJEXT_FLAG, > > + __NR_OBJEXTS_FLAGS =3D (__FIRST_OBJEXT_FLAG << 1), > > }; > > > > #define OBJEXTS_FLAGS_MASK (__NR_OBJEXTS_FLAGS - 1) > > diff --git a/mm/slab.h b/mm/slab.h > > index cf332a839bf4..7bb3900f83ef 100644 > > --- a/mm/slab.h > > +++ b/mm/slab.h > > @@ -586,9 +586,34 @@ static inline void mark_objexts_empty(struct slabo= bj_ext *obj_exts) > > } > > } > > > > +static inline void mark_failed_objexts_alloc(struct slab *slab) > > +{ > > + slab->obj_exts =3D OBJEXTS_ALLOC_FAIL; > > Uh, does this mean slab->obj_exts is suddenly non-NULL? Is everything > that accesses obj_exts expecting this? Hi Kees, Thank you for the reviews! Yes, I believe everything that accesses slab->obj_exts directly (currently alloc_slab_obj_exts() and free_slab_obj_exts()) handle this special non-NULL case. kfence_init_pool() initialized slab->obj_exts directly, but since it's setting it and not accessing it, it does not need to handle OBJEXTS_ALLOC_FAIL. All other slab->obj_exts users use slab_obj_exts() which applies OBJEXTS_FLAGS_MASK and masks out any special bits. Thanks, Suren. > > -Kees > > > +} > > + > > +static inline void handle_failed_objexts_alloc(unsigned long obj_exts, > > + struct slabobj_ext *vec, unsigned int objects) > > +{ > > + /* > > + * If vector previously failed to allocate then we have live > > + * objects with no tag reference. Mark all references in this > > + * vector as empty to avoid warnings later on. > > + */ > > + if (obj_exts & OBJEXTS_ALLOC_FAIL) { > > + unsigned int i; > > + > > + for (i =3D 0; i < objects; i++) > > + set_codetag_empty(&vec[i].ref); > > + } > > +} > > + > > + > > #else /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ > > > > static inline void mark_objexts_empty(struct slabobj_ext *obj_exts) {} > > +static inline void mark_failed_objexts_alloc(struct slab *slab) {} > > +static inline void handle_failed_objexts_alloc(unsigned long obj_exts, > > + struct slabobj_ext *vec, unsigned int objects) {} > > > > #endif /* CONFIG_MEM_ALLOC_PROFILING_DEBUG */ > > > > diff --git a/mm/slab_common.c b/mm/slab_common.c > > index d5f75d04ced2..489c7a8ba8f1 100644 > > --- a/mm/slab_common.c > > +++ b/mm/slab_common.c > > @@ -214,29 +214,37 @@ int alloc_slab_obj_exts(struct slab *slab, struct= kmem_cache *s, > > gfp_t gfp, bool new_slab) > > { > > unsigned int objects =3D objs_per_slab(s, slab); > > - unsigned long obj_exts; > > - void *vec; > > + unsigned long new_exts; > > + unsigned long old_exts; > > + struct slabobj_ext *vec; > > > > gfp &=3D ~OBJCGS_CLEAR_MASK; > > /* Prevent recursive extension vector allocation */ > > gfp |=3D __GFP_NO_OBJ_EXT; > > vec =3D kcalloc_node(objects, sizeof(struct slabobj_ext), gfp, > > slab_nid(slab)); > > - if (!vec) > > + if (!vec) { > > + /* Mark vectors which failed to allocate */ > > + if (new_slab) > > + mark_failed_objexts_alloc(slab); > > + > > return -ENOMEM; > > + } > > > > - obj_exts =3D (unsigned long)vec; > > + new_exts =3D (unsigned long)vec; > > #ifdef CONFIG_MEMCG > > - obj_exts |=3D MEMCG_DATA_OBJEXTS; > > + new_exts |=3D MEMCG_DATA_OBJEXTS; > > #endif > > + old_exts =3D slab->obj_exts; > > + handle_failed_objexts_alloc(old_exts, vec, objects); > > if (new_slab) { > > /* > > * If the slab is brand new and nobody can yet access its > > * obj_exts, no synchronization is required and obj_exts = can > > * be simply assigned. > > */ > > - slab->obj_exts =3D obj_exts; > > - } else if (cmpxchg(&slab->obj_exts, 0, obj_exts)) { > > + slab->obj_exts =3D new_exts; > > + } else if (cmpxchg(&slab->obj_exts, old_exts, new_exts) !=3D old_= exts) { > > /* > > * If the slab is already in use, somebody can allocate a= nd > > * assign slabobj_exts in parallel. In this case the exis= ting > > -- > > 2.43.0.687.g38aa6559b0-goog > > > > -- > Kees Cook