mm/slab: reject unsupported kmalloc() sizes

kmalloc() is used to allocate physically contiguous memory for kernel
allocations. For requests larger than KMALLOC_MAX_CACHE_SIZE, kmalloc()
uses the page allocator and can only support up to KMALLOC_MAX_SIZE. For
request sizes bigger than KMALLOC_MAX_SIZE, the page allocator can emit a
WARN because kmalloc() allocates an order greater than MAX_PAGE_ORDER. To
make the KMALLOC_MAX_SIZE limit more explicit instead of relying on the
page allocator check, add a KMALLOC_MAX_SIZE check inside kmalloc() to emit
a WARN and return NULL for requested sizes bigger than KMALLOC_MAX_SIZE.
Like the WARN in the page allocator and kvmalloc(), allow __GFP_NOWARN to
suppress the WARN.

Suggested-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Zi Yan <ziy@nvidia.com>
Link: https://patch.msgid.link/20260830-limit_kmalloc_size-v2-1-bf4ca9c63c88@nvidia.com
Reviewed-by: Harry Yoo (Meta) <harry@kernel.org>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>

0 files changed, 0 insertions, 0 deletions