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Tue, 28 Oct 2025 20:23:02 -0700 (PDT) MIME-Version: 1.0 References: <20251029014317.1533488-1-hao.ge@linux.dev> In-Reply-To: <20251029014317.1533488-1-hao.ge@linux.dev> From: Suren Baghdasaryan Date: Tue, 28 Oct 2025 20:22:51 -0700 X-Gm-Features: AWmQ_bnWQlp_hgmAQPXCvvIDSyvF6h29V3Rm7M2r8OKX5bFOVKkcR6boUbLHCuw Message-ID: Subject: Re: [PATCH v2] codetag: debug: handle existing CODETAG_EMPTY in mark_objexts_empty for slabobj_ext To: Hao Ge Cc: Vlastimil Babka , Andrew Morton , Christoph Lameter , David Rientjes , Roman Gushchin , Harry Yoo , Shakeel Butt , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Hao Ge , stable@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: x5cch8oun3xes9gi5u9ahy6j91dcp1at X-Rspam-User: X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 1457EC0006 X-HE-Tag: 1761708183-727133 X-HE-Meta: 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 fTWQM7/s hAy12G0IL1NnnvzAFdwvLtpgzBPH3JX8KUJ7CowT78t5rUCaQcu9qhX+woHejNWl1PO9DqTV/7qhxK2z/aFIuzpW5P7ibIV1llu5Tcz/DxbOw1C+hEfd24WdkTRethRPuspp+7tZyHfrSWFhxAUXHSp2bPr4NXu8sHbirgRFeIvIYqqaPEmTOUoldA8/SlZX87viJmfEKbuTTaqCBqthb+rALQBIH76X+ZcWsBhX8Uc9JG/MSUKSviu4wjXEX2RvEuJlbxH4nXB1OLniszSguTQiT+ka7Tnl5ntqb 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 Tue, Oct 28, 2025 at 6:44=E2=80=AFPM Hao Ge wrote: > > From: Hao Ge > > When alloc_slab_obj_exts() fails and then later succeeds in allocating > a slab extension vector, it calls handle_failed_objexts_alloc() to > mark all objects in the vector as empty. As a result all objects in > this slab (slabA) will have their extensions set to CODETAG_EMPTY. > Later on if this slabA is used to allocate a slabobj_ext vector for > another slab (slabB), we end up with the slabB->obj_exts pointing to a > slabobj_ext vector that itself has a non-NULL slabobj_ext equal to > CODETAG_EMPTY. When slabB gets freed, free_slab_obj_exts() is called > to free slabB->obj_exts vector. free_slab_obj_exts() calls > mark_objexts_empty(slabB->obj_exts) which will generate a warning > because it expects slabobj_ext vectors to have a NULL obj_ext, not > CODETAG_EMPTY. > > Modify mark_objexts_empty() to skip the warning and setting the > obj_ext value if it's already set to CODETAG_EMPTY. > > Fixes: 09c46563ff6d ("codetag: debug: introduce OBJEXTS_ALLOC_FAIL to mar= k failed slab_ext allocations") > Cc: > Signed-off-by: Hao Ge Reviewed-by: Suren Baghdasaryan > --- > v2: Update the commit message and code comments for greater accuracy, > incorporating Suren's suggestions. > Thanks for Suren's help. > --- > mm/slub.c | 6 +++++- > 1 file changed, 5 insertions(+), 1 deletion(-) > > diff --git a/mm/slub.c b/mm/slub.c > index d4367f25b20d..589c596163c4 100644 > --- a/mm/slub.c > +++ b/mm/slub.c > @@ -2046,7 +2046,11 @@ static inline void mark_objexts_empty(struct slabo= bj_ext *obj_exts) > if (slab_exts) { > unsigned int offs =3D obj_to_index(obj_exts_slab->slab_ca= che, > obj_exts_slab, obj_exts)= ; > - /* codetag should be NULL */ > + > + if (unlikely(is_codetag_empty(&slab_exts[offs].ref))) > + return; > + > + /* codetag should be NULL here */ > WARN_ON(slab_exts[offs].ref.ct); > set_codetag_empty(&slab_exts[offs].ref); > } > -- > 2.25.1 > >