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[185.121.47.193]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a72452140e0sm409649266b.217.2024.06.26.04.43.26 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Jun 2024 04:43:26 -0700 (PDT) From: "Uladzislau Rezki (Sony)" To: linux-mm@kvack.org, Andrew Morton Cc: LKML , Baoquan He , Hailong Liu , Christoph Hellwig , Nick Bowler , Uladzislau Rezki , Oleksiy Avramchenko Subject: [PATCH] mm: vmalloc: Check if a hash-index is in cpu_possible_mask Date: Wed, 26 Jun 2024 13:43:24 +0200 Message-Id: <20240626114324.87334-1-urezki@gmail.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" The problem is that there are systems where cpu_possible_mask has gaps between set CPUs, for example SPARC. In this scenario addr_to_vb_xa() hash function can return an index which accesses to not-possible and not setup CPU area using per_cpu() macro. A per-cpu vmap_block_queue is also used as hash table assuming that incorrectly assumes the cpu_possible_mask has not gaps. Fix it by adjusting an index to a next possible CPU. Fixes: 062eacf57ad9 ("mm: vmalloc: remove a global vmap_blocks xarray") Reported-by: Nick Bowler Closes: https://lore.kernel.org/linux-kernel/ZntjIE6msJbF8zTa@MiWiFi-R3L-sr= v/T/ Signed-off-by: Uladzislau Rezki (Sony) Reviewed-by: Baoquan He --- mm/vmalloc.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/mm/vmalloc.c b/mm/vmalloc.c index b4c42da9f3901..6b783baf12a14 100644 --- a/mm/vmalloc.c +++ b/mm/vmalloc.c @@ -2544,7 +2544,15 @@ static DEFINE_PER_CPU(struct vmap_block_queue, vmap_= block_queue); static struct xarray * addr_to_vb_xa(unsigned long addr) { - int index =3D (addr / VMAP_BLOCK_SIZE) % num_possible_cpus(); + int index =3D (addr / VMAP_BLOCK_SIZE) % nr_cpu_ids; + + /* + * Please note, nr_cpu_ids points on a highest set + * possible bit, i.e. we never invoke cpumask_next() + * if an index points on it which is nr_cpu_ids - 1. + */ + if (!cpu_possible(index)) + index =3D cpumask_next(index, cpu_possible_mask); =20 return &per_cpu(vmap_block_queue, index).vmap_blocks; } --=20 2.39.2