Messages in this thread Patch in this message | | | From | Zheng Yejian <> | Subject | [PATCH] ftrace: Fix possible warning on checking all pages used in ftrace_process_locs() | Date | Tue, 11 Jul 2023 05:29:58 +0800 |
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As comments in ftrace_process_locs(), there may be NULL pointers in mcount_loc section: > Some architecture linkers will pad between > the different mcount_loc sections of different > object files to satisfy alignments. > Skip any NULL pointers.
After 20e5227e9f55 ("ftrace: allow NULL pointers in mcount_loc"), NULL pointers will be accounted when allocating ftrace pages but skipped before adding into ftrace pages, this may result in some pages not being used. Then after 706c81f87f84 ("ftrace: Remove extra helper functions"), warning may occur at: WARN_ON(pg->next);
So we may need to skip NULL pointers before allocating ftrace pages.
Fixes: 706c81f87f84 ("ftrace: Remove extra helper functions") Signed-off-by: Zheng Yejian <zhengyejian1@huawei.com> --- kernel/trace/ftrace.c | 10 ++++++++++ 1 file changed, 10 insertions(+)
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c index 3740aca79fe7..5b474165df31 100644 --- a/kernel/trace/ftrace.c +++ b/kernel/trace/ftrace.c @@ -6485,6 +6485,16 @@ static int ftrace_process_locs(struct module *mod, if (!count) return 0; + p = start; + while (p < end) { + /* + * Refer to conments below, there may be NULL pointers, + * skip them before allocating pages + */ + addr = ftrace_call_adjust(*p++); + if (!addr) + count--; + } /* * Sorting mcount in vmlinux at build time depend on * CONFIG_BUILDTIME_MCOUNT_SORT, while mcount loc in -- 2.25.1
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