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Mon, 12 Feb 2024 14:49:34 -0800 (PST) Date: Mon, 12 Feb 2024 14:49:34 -0800 From: Kees Cook To: Suren Baghdasaryan 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 Subject: Re: [PATCH v3 34/35] codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mark failed slab_ext allocations Message-ID: <202402121448.AF0AA8E@keescook> References: <20240212213922.783301-1-surenb@google.com> <20240212213922.783301-35-surenb@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240212213922.783301-35-surenb@google.com> X-Rspam-User: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: AACAA100013 X-Stat-Signature: tafkx9ycjyaff4pu1tptjb7sbjz851n3 X-HE-Tag: 1707778176-101081 X-HE-Meta: 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 dT/MQGIL nKfTbCGIZB3GmVTC/ShcfFijpgFKAM88oL+Wa9r9WbIF3DAFKQ6xHmR1Q2dBEE9AD+rXhoCVnfjNzD2WWCPWSEVxi0WZmwidBhBC7GuxOz1WXVmkFQIvi2wxhaz9/TpRd2z+sWaQR6dPOoZEQns+AW0CajP5J6uZb9r96sAgLTCSPxm5mKpgNNPumScif7NxQax28TAxm+5+qA+FsHZkmR2e+2h/KKBVP8Q+i5cZE/abfnmrJRFFveo5wBZfMe/rOcyUmDguS5SFkgy6I95grHnqgHxoGE+87zsa0FGE7XO3mSqiwkxsx5hOFIruBhXqJ4sS6NxMboXwXMtlO0zZkGVDsjSTOOHRA4blzQgtvLIRqVjq5qPvclx56zrpYQ1Qz5NkXJlva9Uh2eftwyViKojQCwXlkl84PIpQFKwY2ibvqoGIKuJnE+5J8zJU2AH5nuaDgt5otA1u0xHhUeyvlkppeBIgBrs9Gjf2+dckQY8hMwOPj60TG3q5YkQ== 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 01:39:20PM -0800, Suren Baghdasaryan wrote: > If slabobj_ext vector allocation for a slab object fails and later on it > 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 flag > stored in the lower bits of slab->obj_exts. When new allocation succeeds > 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 = __FIRST_OBJEXT_FLAG, > /* the next bit after the last actual flag */ > - __NR_OBJEXTS_FLAGS = __FIRST_OBJEXT_FLAG, > + __NR_OBJEXTS_FLAGS = (__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 slabobj_ext *obj_exts) > } > } > > +static inline void mark_failed_objexts_alloc(struct slab *slab) > +{ > + slab->obj_exts = OBJEXTS_ALLOC_FAIL; Uh, does this mean slab->obj_exts is suddenly non-NULL? Is everything that accesses obj_exts expecting this? -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 = 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 = objs_per_slab(s, slab); > - unsigned long obj_exts; > - void *vec; > + unsigned long new_exts; > + unsigned long old_exts; > + struct slabobj_ext *vec; > > gfp &= ~OBJCGS_CLEAR_MASK; > /* Prevent recursive extension vector allocation */ > gfp |= __GFP_NO_OBJ_EXT; > vec = 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 = (unsigned long)vec; > + new_exts = (unsigned long)vec; > #ifdef CONFIG_MEMCG > - obj_exts |= MEMCG_DATA_OBJEXTS; > + new_exts |= MEMCG_DATA_OBJEXTS; > #endif > + old_exts = 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 = obj_exts; > - } else if (cmpxchg(&slab->obj_exts, 0, obj_exts)) { > + slab->obj_exts = new_exts; > + } else if (cmpxchg(&slab->obj_exts, old_exts, new_exts) != old_exts) { > /* > * If the slab is already in use, somebody can allocate and > * assign slabobj_exts in parallel. In this case the existing > -- > 2.43.0.687.g38aa6559b0-goog > -- Kees Cook