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

[Intel]

On 4/8/21 9:15 PM, Zack Rusin wrote:
Lets make sure we don't use pud hugepage helpers on architectures
which do not support it. This fixes the code on arm64.
nits:

Perhaps be a little more specific about what it fixes? I figure it's a 
compilation failure?
Also please use imperative form: "Fix the code arm64" rather than "This 
fixes the code on arm64"

Other than that LGTM.

Reviewed-by: Thomas Hellström (Intel) <thomas...@shipmail.org>



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

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;
        }
  
+#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
        /* Huge pud */
        walk->action = ACTION_CONTINUE;
        if (pud_trans_huge(pudval) || pud_devmap(pudval))
                WARN_ON(pud_write(pudval) || pud_dirty(pudval));
+#endif
  
  	return 0;
  }