diff options
author | Ritesh Harjani (IBM) <ritesh.list@gmail.com> | 2024-11-13 19:49:54 +0530 |
---|---|---|
committer | Andrew Morton <akpm@linux-foundation.org> | 2024-11-14 22:49:19 -0800 |
commit | 2532e6c74a67e65b95f310946e0c0e0a41b3a34b (patch) | |
tree | 5e884677ee6df8ea21f441803a7452c4f3fbeae9 /mm | |
parent | 811808d365398680b628d2b88aafeba77c88691a (diff) |
cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
cma_init_reserved_mem() checks base and size alignment with
CMA_MIN_ALIGNMENT_BYTES. However, some users might call this during early
boot when pageblock_order is 0. That means if base and size does not have
pageblock_order alignment, it can cause functional failures during cma
activate area.
So let's enforce pageblock_order to be non-zero during
cma_init_reserved_mem() to catch such wrong usages.
1. This was seen with fadump on PowerPC which was calling
cma_init_reserved_mem() before the pageblock_order was initialized.
This is now fixed in the fadump on PowerPC itself. The details of that
can be found in the patch including the userspace-visible effect of the
issue [1].
2. However it was also decided that we should add a stronger
enforcement check within cma_init_reserved_mem() to catch such wrong
usages [2]. Hence this patch. This is ok to be in -next and there is
no "Fixes" tag required for this patch.
[1]: https://lore.kernel.org/all/3ae208e48c0d9cefe53d2dc4f593388067405b7d.1729146153.git.ritesh.list@gmail.com/
[2]: https://lore.kernel.org/all/83eb128e-4f06-4725-a843-a4563f246a44@redhat.com/
Link: https://lkml.kernel.org/r/e274344b44d5f80fa54c52f530387257fe99ec65.1731505681.git.ritesh.list@gmail.com
Signed-off-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r-- | mm/cma.c | 9 |
1 files changed, 9 insertions, 0 deletions
@@ -181,6 +181,15 @@ int __init cma_init_reserved_mem(phys_addr_t base, phys_addr_t size, if (!size || !memblock_is_region_reserved(base, size)) return -EINVAL; + /* + * CMA uses CMA_MIN_ALIGNMENT_BYTES as alignment requirement which + * needs pageblock_order to be initialized. Let's enforce it. + */ + if (!pageblock_order) { + pr_err("pageblock_order not yet initialized. Called during early boot?\n"); + return -EINVAL; + } + /* ensure minimal alignment required by mm core */ if (!IS_ALIGNED(base | size, CMA_MIN_ALIGNMENT_BYTES)) return -EINVAL; |