After a recent change in clang to expose uninitialized warnings from const variables [1], there is a 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().
Cc: stable@vger.kernel.org Fixes: 66790e9a735b ("mm/ksm: add sysfs knobs for advisor") Closes: https://github.com/ClangBuiltLinux/linux/issues/2100 Link: https://github.com/llvm/llvm-project/commit/2464313eef01c5b1edf0eccf57a32cde... [1] Signed-off-by: Nathan Chancellor nathan@kernel.org --- mm/ksm.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
diff --git a/mm/ksm.c b/mm/ksm.c index 2b0210d41c55..160787bb121c 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -3682,10 +3682,10 @@ static ssize_t advisor_mode_show(struct kobject *kobj, { 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); }
--- base-commit: fed48693bdfeca666f7536ba88a05e9a4e5523b6 change-id: 20250715-ksm-fix-clang-21-uninit-warning-bea5a6b886ce
Best regards, -- Nathan Chancellor nathan@kernel.org