[PATCH v6 06/19] mm/ioremap: add slab availability checking in ioremap_prot

Baoquan He
2023-06-09T07:56:29Z

Several architectures has done checking if slab if available in
ioremap_prot(). In fact it should be done in generic ioremap_prot()
since on any architecutre, slab allocator must be available before
get_vm_area_caller() and vunmap() are used.

Add the checking into generic_ioremap_prot().

Suggested-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Baoquan He <bhe@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
---
v5-v6:
Add WARN_ON_ONCE to aid debugging - Christoph.

mm/ioremap.c | 4 ++++
1 file changed, 4 insertions(+)

diff --git a/mm/ioremap.c b/mm/ioremap.c
index 9f34a8f90b58..86b82ec27d2b 100644
--- a/mm/ioremap.c
+++ b/mm/ioremap.c
@@ -18,6 +18,10 @@ void __iomem *generic_ioremap_prot(phys_addr_t phys_addr, size_t size,
phys_addr_t last_addr;
struct vm_struct *area;

+ /* An early platform driver might end up here */
+ if (WARN_ON_ONCE(!slab_is_available()))
+ return NULL;
+
/* Disallow wrap-around or zero size */
last_addr = phys_addr + size - 1;
if (!size || last_addr < phys_addr)
--
2.34.1