Thread (12 messages) 12 messages, 8 authors, 2021-02-05

Re: [PATCH] mm/mremap: fix BUILD_BUG_ON() error in get_extent

From: Vlastimil Babka <hidden>
Date: 2021-01-04 11:35:29
Also in: lkml

The subject should say BUILD_BUG()

On 12/30/20 4:40 PM, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@arndb.de>

clang cannt evaluate this function argument at compile time
when the function is not inlined, which leads to a link
time failure:

ld.lld: error: undefined symbol: __compiletime_assert_414
quoted
quoted
quoted
referenced by mremap.c
              mremap.o:(get_extent) in archive mm/built-in.a
Mark the function as __always_inline to avoid it.
Not sure if it's the ideal fix, maybe just convert it to BUG() instead?
Functions shouldn't really have BUILD_BUG depending on parameters and rely on
inlining to make it work...
Fixes: 9ad9718bfa41 ("mm/mremap: calculate extent in one place")
I think it's rather this one that introduces the BUILD_BUG() ?
c49dd3401802 ("mm: speedup mremap on 1GB or larger regions")
quoted hunk ↗ jump to hunk
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 mm/mremap.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/mm/mremap.c b/mm/mremap.c
index c5590afe7165..1cb464a07184 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -336,8 +336,9 @@ enum pgt_entry {
  * valid. Else returns a smaller extent bounded by the end of the source and
  * destination pgt_entry.
  */
-static unsigned long get_extent(enum pgt_entry entry, unsigned long old_addr,
-			unsigned long old_end, unsigned long new_addr)
+static __always_inline unsigned long get_extent(enum pgt_entry entry,
+			unsigned long old_addr, unsigned long old_end,
+			unsigned long new_addr)
 {
 	unsigned long next, extent, mask, size;
 
  
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