linux-kernel - [PATCH -next] mm: pagewalk: Restore err initialization in walk_hugetlb

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Date:   Tue, 23 Aug 2022 08:30:56 -0700
From:   Nathan Chancellor <nathan@...nel.org>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Tom Rix <trix@...hat.com>, Rolf Eike Beer <eb@...ix.com>,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        llvm@...ts.linux.dev, patches@...ts.linux.dev,
        Nathan Chancellor <nathan@...nel.org>
Subject: [PATCH -next] mm: pagewalk: Restore err initialization in walk_hugetlb_range()

Clang warns:

  mm/pagewalk.c:318:12: error: variable 'err' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
                  else if (ops->pte_hole)
                          ^~~~~~~~~~~~~
  mm/pagewalk.c:321:7: note: uninitialized use occurs here
                  if (err)
                      ^~~
  mm/pagewalk.c:318:8: note: remove the 'if' if its condition is always true
                  else if (ops->pte_hole)
                      ^~~~~~~~~~~~~~~~~~
  mm/pagewalk.c:311:10: note: initialize the variable 'err' to silence this warning
                  int err;
                        ^
                          = 0
  1 error generated.

Restore the initialization of err to zero so that it cannot be used
uninitialized.

Fixes: 9ce1db56225a ("mm: pagewalk: make error checks more obvious")
Link: https://github.com/ClangBuiltLinux/linux/issues/1694
Signed-off-by: Nathan Chancellor <nathan@...nel.org>
---

I am sure that SHA is not stable and I expect this to be squashed into
the original change.

 mm/pagewalk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 54b2a1beeeb3..76e5ccda8c88 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -308,7 +308,7 @@ static int walk_hugetlb_range(unsigned long addr, unsigned long end,
 	const struct mm_walk_ops *ops = walk->ops;
 
 	for (; addr < end; addr = next) {
-		int err;
+		int err = 0;
 		pte_t *pte = huge_pte_offset(walk->mm, addr & hmask, sz);
 
 		next = hugetlb_entry_end(h, addr, end);

base-commit: d711de4adbec4cb0b8769bcae971b13293e6d311
-- 
2.37.2