From:   Baoquan He <bhe@redhat.com>
To:     linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, akpm@linux-foundation.org,
        christophe.leroy@csgroup.eu, hch@infradead.org,
        agordeev@linux.ibm.com, wangkefeng.wang@huawei.com,
        schnelle@linux.ibm.com, David.Laight@ACULAB.COM, shorne@gmail.com,
        arnd@arndb.de, Baoquan He <bhe@redhat.com>
Subject: [PATCH v4 05/16] mm/ioremap: add slab availability checking in ioremap_prot
Date:   Thu, 16 Feb 2023 20:34:08 +0800
Message-Id: <20230216123419.461016-6-bhe@redhat.com>
In-Reply-To: <20230216123419.461016-1-bhe@redhat.com>
References: <20230216123419.461016-1-bhe@redhat.com>
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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>
---
 mm/ioremap.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mm/ioremap.c b/mm/ioremap.c
index 9f34a8f90b58..2fbe6b9bc50e 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 (!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