On Thu, Oct 21, 2021 at 11:04 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote:
>
> Clang warns:
>
> mm/memory-failure.c:892:6: error: variable 'extra_pins' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (!mapping) {
> ^~~~~~~~
> mm/memory-failure.c:915:32: note: uninitialized use occurs here
> if (has_extra_refcount(ps, p, extra_pins))
> ^~~~~~~~~~
> mm/memory-failure.c:892:2: note: remove the 'if' if its condition is always false
> if (!mapping) {
> ^~~~~~~~~~~~~~~
> mm/memory-failure.c:879:6: error: variable 'extra_pins' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
> if (PageAnon(p)) {
> ^~~~~~~~~~~
> mm/memory-failure.c:915:32: note: uninitialized use occurs here
> if (has_extra_refcount(ps, p, extra_pins))
> ^~~~~~~~~~
> mm/memory-failure.c:879:2: note: remove the 'if' if its condition is always false
> if (PageAnon(p)) {
> ^~~~~~~~~~~~~~~~~~
> mm/memory-failure.c:871:17: note: initialize the variable 'extra_pins' to silence this warning
> bool extra_pins;
> ^
> = 0
> 2 errors generated.
>
> Initialize extra_pins to false so that it is not used uninitialized.
>
> Fixes: d882a43a0011 ("mm: shmem: don't truncate page if memory failure happens")
> Link: https://github.com/ClangBuiltLinux/linux/issues/1487
> Reported-by: "kernelci.org bot" <bot@xxxxxxxxxxxx>
> Signed-off-by: Nathan Chancellor <nathan@xxxxxxxxxx>
> ---
>
> I am aware the fixes tag is not stable. It is there to convey this
> should be squashed into mm-shmem-dont-truncate-page-if-memory-failure-happens.patch.
Thanks for catching this. Acked-by: Yang Shi <shy828301@xxxxxxxxx>
>
> mm/memory-failure.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memory-failure.c b/mm/memory-failure.c
> index 3b04f0361a58..dba5f0098165 100644
> --- a/mm/memory-failure.c
> +++ b/mm/memory-failure.c
> @@ -868,7 +868,7 @@ static int me_pagecache_clean(struct page_state *ps, struct page *p)
> {
> int ret;
> struct address_space *mapping;
> - bool extra_pins;
> + bool extra_pins = false;
>
> delete_from_lru_cache(p);
>
> --
> 2.33.1.637.gf443b226ca
>
