Thread (11 messages) 11 messages, 4 authors, 2013-12-15

Re: [PATCH v3] powerpc: Fix PTE page address mismatch in pgtable ctor/dtor

From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Date: 2013-12-07 20:32:35
Also in: linux-rt-users

On Sun, 2013-12-08 at 07:27 +1100, Benjamin Herrenschmidt wrote:
On Sat, 2013-12-07 at 09:06 -0500, Hong H. Pham wrote:
quoted
diff --git a/arch/powerpc/include/asm/pgalloc-32.h b/arch/powerpc/include/asm/pgalloc-32.h
index 27b2386..842846c 100644
--- a/arch/powerpc/include/asm/pgalloc-32.h
+++ b/arch/powerpc/include/asm/pgalloc-32.h
@@ -84,10 +84,8 @@ static inline void pgtable_free_tlb(struct mmu_gather *tlb,
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t table,
 				  unsigned long address)
 {
-	struct page *page = page_address(table);
-
 	tlb_flush_pgtable(tlb, address);
-	pgtable_page_dtor(page);
-	pgtable_free_tlb(tlb, page, 0);
+	pgtable_page_dtor(table);
+	pgtable_free_tlb(tlb, page_address(table), 0);
 }
Ok so your description of the problem confused me a bit, but I see that
in the !64K page, pgtable_t is already a struct page so yes, the
page_address() call here is bogus.

However, I also noticed that in the 64k page case, we don't call the dto
at all. Is that a problem ?
Actually we do, just elsewhere... ignore the above.
Also, Aneesh, shouldn't we just fix the disconnect here and have
pgtable_t always be the same type ? The way this is now is confusing
and error prone...
quoted
 #endif /* _ASM_POWERPC_PGALLOC_32_H */
diff --git a/arch/powerpc/include/asm/pgalloc-64.h b/arch/powerpc/include/asm/pgalloc-64.h
index f65e27b..256d6f8 100644
--- a/arch/powerpc/include/asm/pgalloc-64.h
+++ b/arch/powerpc/include/asm/pgalloc-64.h
@@ -144,11 +144,9 @@ static inline void pgtable_free_tlb(struct mmu_gather *tlb,
 static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t table,
 				  unsigned long address)
 {
-	struct page *page = page_address(table);
-
 	tlb_flush_pgtable(tlb, address);
-	pgtable_page_dtor(page);
-	pgtable_free_tlb(tlb, page, 0);
+	pgtable_page_dtor(table);
+	pgtable_free_tlb(tlb, page_address(table), 0);
 }
 
 #else /* if CONFIG_PPC_64K_PAGES */
Ben.


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