linux-kernel - [PATCH v6 06/19] mm/ioremap: add slab availability checking in ioremap

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Message-Id: <20230609075528.9390-7-bhe@redhat.com>
Date:   Fri,  9 Jun 2023 15:55:15 +0800
From:   Baoquan He <bhe@...hat.com>
To:     linux-kernel@...r.kernel.org
Cc:     linux-arch@...r.kernel.org, linux-mm@...ck.org, arnd@...db.de,
        christophe.leroy@...roup.eu, hch@....de, rppt@...nel.org,
        willy@...radead.org, agordeev@...ux.ibm.com,
        wangkefeng.wang@...wei.com, schnelle@...ux.ibm.com,
        David.Laight@...LAB.COM, shorne@...il.com, deller@....de,
        Baoquan He <bhe@...hat.com>
Subject: [PATCH v6 06/19] mm/ioremap: add slab availability checking in ioremap_prot

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@...roup.eu>
Signed-off-by: Baoquan He <bhe@...hat.com>
Reviewed-by: Christoph Hellwig <hch@....de>
Reviewed-by: Kefeng Wang <wangkefeng.wang@...wei.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@...nel.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