[patch 13/13] mm/ioremap: fix iomap_max_page_shift

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From: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Subject: mm/ioremap: fix iomap_max_page_shift

iomap_max_page_shift is expected to contain a page shift, so it can't be a
'bool', has to be an 'unsigned int'

And fix the default values: P4D_SHIFT is when huge iomap is allowed.

However, on some architectures (eg: powerpc book3s/64), P4D_SHIFT is not a
constant so it can't be used to initialise a static variable.  So,
initialise iomap_max_page_shift with a maximum shift supported by the
architecture, it is gated by P4D_SHIFT in vmap_try_huge_p4d() anyway.

Link: https://lkml.kernel.org/r/ad2d366015794a9f21320dcbdd0a8eb98979e9df.1620898113.git.christophe.leroy@xxxxxxxxxx
Fixes: bbc180a5adb0 ("mm: HUGE_VMAP arch support cleanup")
Signed-off-by: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Reviewed-by: Nicholas Piggin <npiggin@xxxxxxxxx>
Reviewed-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 mm/ioremap.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/mm/ioremap.c~mm-ioremap-fix-iomap_max_page_shift
+++ a/mm/ioremap.c
@@ -16,16 +16,16 @@
 #include "pgalloc-track.h"
 
 #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP
-static bool __ro_after_init iomap_max_page_shift = PAGE_SHIFT;
+static unsigned int __ro_after_init iomap_max_page_shift = BITS_PER_LONG - 1;
 
 static int __init set_nohugeiomap(char *str)
 {
-	iomap_max_page_shift = P4D_SHIFT;
+	iomap_max_page_shift = PAGE_SHIFT;
 	return 0;
 }
 early_param("nohugeiomap", set_nohugeiomap);
 #else /* CONFIG_HAVE_ARCH_HUGE_VMAP */
-static const bool iomap_max_page_shift = PAGE_SHIFT;
+static const unsigned int iomap_max_page_shift = PAGE_SHIFT;
 #endif	/* CONFIG_HAVE_ARCH_HUGE_VMAP */
 
 int ioremap_page_range(unsigned long addr,
_



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