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[v2] mm/mapping_dirty_helpers: Guard hugepage pud's usage

Message ID 20210409165151.694574-1-zackr@vmware.com (mailing list archive)
State New
Headers show
Series [v2] mm/mapping_dirty_helpers: Guard hugepage pud's usage | expand

Commit Message

Zack Rusin April 9, 2021, 4:51 p.m. UTC
Mapping dirty helpers have, so far, been only used on X86, but
a port of vmwgfx to ARM64 exposed a problem which results
in a compilation error on ARM64 systems:
mm/mapping_dirty_helpers.c: In function ‘wp_clean_pud_entry’:
mm/mapping_dirty_helpers.c:172:32: error: implicit declaration of function ‘pud_dirty’; did you mean ‘pmd_dirty’? [-Werror=implicit-function-declaration]

This is due to the fact that mapping_dirty_helpers code assumes
that pud_dirty is always defined, which is not the case for
architectures that don't define CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD.

ARM64 arch is a little inconsistent when it comes to PUD
hugepage helpers, e.g. it defines pud_young but not pud_dirty
but regardless of that the core kernel code shouldn't assume
that any of the PUD hugepage helpers are available unless
prevents compilation errors whenever one of the drivers
is ported to new architectures.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Hellström (Intel) <thomas_os@shipmail.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
 mm/mapping_dirty_helpers.c | 2 ++
 1 file changed, 2 insertions(+)
diff mbox series


diff --git a/mm/mapping_dirty_helpers.c b/mm/mapping_dirty_helpers.c
index b59054ef2e10..b890854ec761 100644
--- a/mm/mapping_dirty_helpers.c
+++ b/mm/mapping_dirty_helpers.c
@@ -165,10 +165,12 @@  static int wp_clean_pud_entry(pud_t *pud, unsigned long addr, unsigned long end,
 		return 0;
 	/* Huge pud */
 	walk->action = ACTION_CONTINUE;
 	if (pud_trans_huge(pudval) || pud_devmap(pudval))
 		WARN_ON(pud_write(pudval) || pud_dirty(pudval));
 	return 0;