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authorChristophe Leroy <christophe.leroy@csgroup.eu>2020-06-25 20:30:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2020-06-26 00:27:37 -0700
commit9449c9cb420b249eb6d7dad3953e4686443d7bd9 (patch)
tree633505118f090e396ec7c9224bef5f553b027b7a
parent7f70c2a68a51496289df163f6969d4db7c383f30 (diff)
mm/debug_vm_pgtable: fix build failure with powerpc 8xx
Since commit 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses"), READ_ONCE() cannot be used anymore to read complex page table entries. This leads to: CC mm/debug_vm_pgtable.o In file included from ./include/asm-generic/bug.h:5, from ./arch/powerpc/include/asm/bug.h:109, from ./include/linux/bug.h:5, from ./include/linux/mmdebug.h:5, from ./include/linux/gfp.h:5, from mm/debug_vm_pgtable.c:13: In function 'pte_clear_tests', inlined from 'debug_vm_pgtable' at mm/debug_vm_pgtable.c:363:2: ./include/linux/compiler.h:392:38: error: Unsupported access size for {READ,WRITE}_ONCE(). mm/debug_vm_pgtable.c:249:14: note: in expansion of macro 'READ_ONCE' 249 | pte_t pte = READ_ONCE(*ptep); | ^~~~~~~~~ make[2]: *** [mm/debug_vm_pgtable.o] Error 1 Fix it by using the recently added ptep_get() helper. Link: http://lkml.kernel.org/r/6ca8c972e6c920dc4ae0d4affbed9703afa4d010.1592490570.git.christophe.leroy@csgroup.eu Fixes: 9e343b467c70 ("READ_ONCE: Enforce atomicity for {READ,WRITE}_ONCE() memory accesses") Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Acked-by: Will Deacon <will@kernel.org> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Peter Zijlstra (Intel)" <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/debug_vm_pgtable.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/mm/debug_vm_pgtable.c b/mm/debug_vm_pgtable.c
index e45623016aea..61ab16fb2e36 100644
--- a/mm/debug_vm_pgtable.c
+++ b/mm/debug_vm_pgtable.c
@@ -246,13 +246,13 @@ static void __init pgd_populate_tests(struct mm_struct *mm, pgd_t *pgdp,
static void __init pte_clear_tests(struct mm_struct *mm, pte_t *ptep,
unsigned long vaddr)
{
- pte_t pte = READ_ONCE(*ptep);
+ pte_t pte = ptep_get(ptep);
pte = __pte(pte_val(pte) | RANDOM_ORVALUE);
set_pte_at(mm, vaddr, ptep, pte);
barrier();
pte_clear(mm, vaddr, ptep);
- pte = READ_ONCE(*ptep);
+ pte = ptep_get(ptep);
WARN_ON(!pte_none(pte));
}