releases/4.19.34/mm-sparse-fix-a-bad-comparison.patch

   1 From f288a532a6e95aa11f17245ffad35e2e0e23238d Mon Sep 17 00:00:00 2001
   2 From: Qian Cai <cai@lca.pw>
   3 Date: Tue, 5 Mar 2019 15:50:11 -0800
   4 Subject: mm/sparse: fix a bad comparison
   5
   6 [ Upstream commit d778015ac95bc036af73342c878ab19250e01fe1 ]
   7
   8 next_present_section_nr() could only return an unsigned number -1, so
   9 just check it specifically where compilers will convert -1 to unsigned
  10 if needed.
  11
  12   mm/sparse.c: In function 'sparse_init_nid':
  13   mm/sparse.c:200:20: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
  14          ((section_nr >= 0) &&    \
  15                       ^~
  16   mm/sparse.c:478:2: note: in expansion of macro
  17   'for_each_present_section_nr'
  18     for_each_present_section_nr(pnum_begin, pnum) {
  19     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
  20   mm/sparse.c:200:20: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
  21          ((section_nr >= 0) &&    \
  22                       ^~
  23   mm/sparse.c:497:2: note: in expansion of macro
  24   'for_each_present_section_nr'
  25     for_each_present_section_nr(pnum_begin, pnum) {
  26     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
  27   mm/sparse.c: In function 'sparse_init':
  28   mm/sparse.c:200:20: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
  29          ((section_nr >= 0) &&    \
  30                       ^~
  31   mm/sparse.c:520:2: note: in expansion of macro
  32   'for_each_present_section_nr'
  33     for_each_present_section_nr(pnum_begin + 1, pnum_end) {
  34     ^~~~~~~~~~~~~~~~~~~~~~~~~~~
  35
  36 Link: http://lkml.kernel.org/r/20190228181839.86504-1-cai@lca.pw
  37 Fixes: c4e1be9ec113 ("mm, sparsemem: break out of loops early")
  38 Signed-off-by: Qian Cai <cai@lca.pw>
  39 Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
  40 Cc: Dave Hansen <dave.hansen@linux.intel.com>
  41 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  42 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  43 Signed-off-by: Sasha Levin <sashal@kernel.org>
  44 ---
  45  mm/sparse.c | 2 +-
  46  1 file changed, 1 insertion(+), 1 deletion(-)
  47
  48 diff --git a/mm/sparse.c b/mm/sparse.c
  49 index 10b07eea9a6e..45950a074bdb 100644
  50 --- a/mm/sparse.c
  51 +++ b/mm/sparse.c
  52 @@ -196,7 +196,7 @@ static inline int next_present_section_nr(int section_nr)
  53  }
  54  #define for_each_present_section_nr(start, section_nr)         \
  55         for (section_nr = next_present_section_nr(start-1);     \
  56 -            ((section_nr >= 0) &&                              \
  57 +            ((section_nr != -1) &&                             \
  58               (section_nr <= __highest_present_section_nr));    \
  59              section_nr = next_present_section_nr(section_nr))
  60
  61 --
  62 2.19.1
  63