linux-kernel - [PATCH 2/2] powerpc: Don't ignore errors from set_memory_{n}p() in __kernel_map

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Message-ID: <20ef75884aa6a636e8298736f3d1056b0793d3d9.1708078640.git.christophe.leroy@csgroup.eu>
Date: Fri, 16 Feb 2024 11:17:34 +0100
From: Christophe Leroy <christophe.leroy@...roup.eu>
To: Michael Ellerman <mpe@...erman.id.au>,
	Nicholas Piggin <npiggin@...il.com>
Cc: Christophe Leroy <christophe.leroy@...roup.eu>,
	linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: [PATCH 2/2] powerpc: Don't ignore errors from set_memory_{n}p() in __kernel_map_pages()

set_memory_p() and set_memory_np() can fail.

As mentioned in linux/mm.h:

/*
 * To support DEBUG_PAGEALLOC architecture must ensure that
 * __kernel_map_pages() never fails
 */

So panic in case set_memory_p() or set_memory_np() fail
in __kernel_map_pages().

Link: https://github.com/KSPP/linux/issues/7
Signed-off-by: Christophe Leroy <christophe.leroy@...roup.eu>
---
 arch/powerpc/include/asm/book3s/64/hash.h |  2 +-
 arch/powerpc/mm/book3s64/hash_utils.c     |  3 ++-
 arch/powerpc/mm/pageattr.c                | 10 +++++++---
 3 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/arch/powerpc/include/asm/book3s/64/hash.h b/arch/powerpc/include/asm/book3s/64/hash.h
index 6e70ae511631..8f47ae79f2a6 100644
--- a/arch/powerpc/include/asm/book3s/64/hash.h
+++ b/arch/powerpc/include/asm/book3s/64/hash.h
@@ -269,7 +269,7 @@ int hash__create_section_mapping(unsigned long start, unsigned long end,
 				 int nid, pgprot_t prot);
 int hash__remove_section_mapping(unsigned long start, unsigned long end);
 
-void hash__kernel_map_pages(struct page *page, int numpages, int enable);
+int hash__kernel_map_pages(struct page *page, int numpages, int enable);
 
 #endif /* !__ASSEMBLY__ */
 #endif /* __KERNEL__ */
diff --git a/arch/powerpc/mm/book3s64/hash_utils.c b/arch/powerpc/mm/book3s64/hash_utils.c
index 0626a25b0d72..01c3b4b65241 100644
--- a/arch/powerpc/mm/book3s64/hash_utils.c
+++ b/arch/powerpc/mm/book3s64/hash_utils.c
@@ -2172,7 +2172,7 @@ static void kernel_unmap_linear_page(unsigned long vaddr, unsigned long lmi)
 				     mmu_kernel_ssize, 0);
 }
 
-void hash__kernel_map_pages(struct page *page, int numpages, int enable)
+int hash__kernel_map_pages(struct page *page, int numpages, int enable)
 {
 	unsigned long flags, vaddr, lmi;
 	int i;
@@ -2189,6 +2189,7 @@ void hash__kernel_map_pages(struct page *page, int numpages, int enable)
 			kernel_unmap_linear_page(vaddr, lmi);
 	}
 	local_irq_restore(flags);
+	return 0;
 }
 #endif /* CONFIG_DEBUG_PAGEALLOC || CONFIG_KFENCE */
 
diff --git a/arch/powerpc/mm/pageattr.c b/arch/powerpc/mm/pageattr.c
index 16b8d20d6ca8..62b678585878 100644
--- a/arch/powerpc/mm/pageattr.c
+++ b/arch/powerpc/mm/pageattr.c
@@ -106,17 +106,21 @@ int change_memory_attr(unsigned long addr, int numpages, long action)
 #ifdef CONFIG_ARCH_SUPPORTS_DEBUG_PAGEALLOC
 void __kernel_map_pages(struct page *page, int numpages, int enable)
 {
+	int err;
 	unsigned long addr = (unsigned long)page_address(page);
 
 	if (PageHighMem(page))
 		return;
 
 	if (IS_ENABLED(CONFIG_PPC_BOOK3S_64) && !radix_enabled())
-		hash__kernel_map_pages(page, numpages, enable);
+		err = hash__kernel_map_pages(page, numpages, enable);
 	else if (enable)
-		set_memory_p(addr, numpages);
+		err = set_memory_p(addr, numpages);
 	else
-		set_memory_np(addr, numpages);
+		err = set_memory_np(addr, numpages);
+
+	if (err)
+		panic("%s: set_memory_%sp() failed\n", enable ? "" : "n");
 }
 #endif
 #endif
-- 
2.43.0