6.12-stable review patch. If anyone has any objections, please let me know.
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From: Nathan Chancellor nathan@kernel.org
commit 153ad566724fe6f57b14f66e9726d295d22e576d upstream.
After a recent change in clang to expose uninitialized warnings from const variables [1], there is a false positive warning from the if statement in advisor_mode_show().
mm/ksm.c:3687:11: error: variable 'output' is used uninitialized whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized] 3687 | else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME) | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ mm/ksm.c:3690:33: note: uninitialized use occurs here 3690 | return sysfs_emit(buf, "%s\n", output); | ^~~~~~
Rewrite the if statement to implicitly make KSM_ADVISOR_NONE the else branch so that it is obvious to the compiler that ksm_advisor can only be KSM_ADVISOR_NONE or KSM_ADVISOR_SCAN_TIME due to the assignments in advisor_mode_store().
Link: https://lkml.kernel.org/r/20250715-ksm-fix-clang-21-uninit-warning-v1-1-f443... Fixes: 66790e9a735b ("mm/ksm: add sysfs knobs for advisor") Signed-off-by: Nathan Chancellor nathan@kernel.org Closes: https://github.com/ClangBuiltLinux/linux/issues/2100 Link: https://github.com/llvm/llvm-project/commit/2464313eef01c5b1edf0eccf57a32cde... [1] Acked-by: David Hildenbrand david@redhat.com Cc: Chengming Zhou chengming.zhou@linux.dev Cc: Stefan Roesch shr@devkernel.io Cc: xu xin xu.xin16@zte.com.cn Cc: stable@vger.kernel.org Signed-off-by: Andrew Morton akpm@linux-foundation.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- mm/ksm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/mm/ksm.c +++ b/mm/ksm.c @@ -3643,10 +3643,10 @@ static ssize_t advisor_mode_show(struct { const char *output;
- if (ksm_advisor == KSM_ADVISOR_NONE) - output = "[none] scan-time"; - else if (ksm_advisor == KSM_ADVISOR_SCAN_TIME) + if (ksm_advisor == KSM_ADVISOR_SCAN_TIME) output = "none [scan-time]"; + else + output = "[none] scan-time";
return sysfs_emit(buf, "%s\n", output); }