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mm/mapping_dirty_helpers: guard hugepage pud's usage

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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 CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
is defined.  This prevents compilation errors whenever one of the
drivers is ported to new architectures.

Link: https://lkml.kernel.org/r/20210409165151.694574-1-zackr@vmware.com
Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: Thomas Hellstrm (Intel) <thomas_os@shipmail.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Zack Rusin 2021-04-16 15:46:18 -07:00 committed by Linus Torvalds
parent f4bf09dc3a
commit 94036f4c88
1 changed files with 2 additions and 0 deletions
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2
mm/mapping_dirty_helpers.c
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@ -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;
}