The patch titled
Subject: mm: vmalloc: check if a hash-index is in cpu_possible_mask
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
mm-vmalloc-check-if-a-hash-index-is-in-cpu_possible_mask.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-vmalloc-check-if-a-hash-index-is-in-cpu_possible_mask.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Uladzislau Rezki (Sony)" <urezki@xxxxxxxxx>
Subject: mm: vmalloc: check if a hash-index is in cpu_possible_mask
Date: Wed, 26 Jun 2024 16:03:30 +0200
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. This results in an oops on SPARC.
A per-cpu vmap_block_queue is also used as hash table, incorrectly
assuming the cpu_possible_mask has no gaps. Fix it by adjusting an index
to a next possible CPU.
Link: https://lkml.kernel.org/r/20240626140330.89836-1-urezki@xxxxxxxxx
Fixes: 062eacf57ad9 ("mm: vmalloc: remove a global vmap_blocks xarray")
Reported-by: Nick Bowler <nbowler@xxxxxxxxxx>
Closes: https://lore.kernel.org/linux-kernel/ZntjIE6msJbF8zTa@MiWiFi-R3L-srv/T/
Signed-off-by: Uladzislau Rezki (Sony) <urezki@xxxxxxxxx>
Cc: Baoquan He <bhe@xxxxxxxxxx>
Cc: Christoph Hellwig <hch@xxxxxxxxxxxxx>
Cc: Hailong.Liu <hailong.liu@xxxxxxxx>
Cc: Oleksiy Avramchenko <oleksiy.avramchenko@xxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/vmalloc.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
--- a/mm/vmalloc.c~mm-vmalloc-check-if-a-hash-index-is-in-cpu_possible_mask
+++ a/mm/vmalloc.c
@@ -2543,7 +2543,15 @@ static DEFINE_PER_CPU(struct vmap_block_
static struct xarray *
addr_to_vb_xa(unsigned long addr)
{
- int index = (addr / VMAP_BLOCK_SIZE) % num_possible_cpus();
+ int index = (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 = cpumask_next(index, cpu_possible_mask);
return &per_cpu(vmap_block_queue, index).vmap_blocks;
}
_
Patches currently in -mm which might be from urezki@xxxxxxxxx are
mm-vmalloc-check-if-a-hash-index-is-in-cpu_possible_mask.patch
