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[v2] mm/ioremap: Fix iomap_max_page_shift

Message ID ad2d366015794a9f21320dcbdd0a8eb98979e9df.1620898113.git.christophe.leroy@csgroup.eu
State Not Applicable
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Series [v2] mm/ioremap: Fix iomap_max_page_shift | expand
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snowpatch_ozlabs/apply_patch success Successfully applied on branch powerpc/merge (1fab3666d738e4af3a7450c44441310e4d7a7e53)
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Commit Message

Christophe Leroy May 13, 2021, 9:29 a.m. UTC
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()

Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Fixes: bbc180a5adb0 ("mm: HUGE_VMAP arch support cleanup")
Reviewed-by: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
v2: Initialise with BITS_PER_LONG - 1 instead of P4D_SHIFT which is not a constant on powerpc/64.
 mm/ioremap.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
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diff --git a/mm/ioremap.c b/mm/ioremap.c
index d1dcc7e744ac..8ee0136f8cb0 100644
--- a/mm/ioremap.c
+++ b/mm/ioremap.c
@@ -16,16 +16,16 @@ 
 #include "pgalloc-track.h"
-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);
-static const bool iomap_max_page_shift = PAGE_SHIFT;
+static const unsigned int iomap_max_page_shift = PAGE_SHIFT;
 int ioremap_page_range(unsigned long addr,