Hi Masami, kernel test robot noticed the following build errors:
[auto build test ERROR on trace/for-next] [also build test ERROR on geert-m68k/for-next geert-m68k/for-linus openrisc/for-next deller-parisc/for-next powerpc/next powerpc/fixes s390/features uml/next tip/x86/core linus/master uml/fixes v7.0-rc4 next-20260320] [If your patch is applied to the wrong git tree, kindly drop us a note. And when submitting patch, we suggest to use '--base' as documented in https://git-scm.com/docs/git-format-patch#_base_tree_information] url: https://github.com/intel-lab-lkp/linux/commits/Masami-Hiramatsu-Google/ring-buffer-Fix-to-update-per-subbuf-entries-of-persistent-ring-buffer/20260322-122412 base: https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace for-next patch link: https://lore.kernel.org/r/177391156211.193994.7531495945584650297.stgit%40mhiramat.tok.corp.google.com patch subject: [PATCH v11 4/5] ring-buffer: Skip invalid sub-buffers when rewinding persistent ring buffer config: arc-defconfig (https://download.01.org/0day-ci/archive/20260322/[email protected]/config) compiler: arc-linux-gcc (GCC) 15.2.0 reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260322/[email protected]/reproduce) If you fix the issue in a separate patch/commit (i.e. not just a new version of the same patch/commit), kindly add following tags | Reported-by: kernel test robot <[email protected]> | Closes: https://lore.kernel.org/oe-kbuild-all/[email protected]/ All errors (new ones prefixed by >>): In file included from ./arch/arc/include/generated/asm/local.h:1, from include/linux/ring_buffer_types.h:5, from kernel/trace/ring_buffer.c:7: kernel/trace/ring_buffer.c: In function 'rb_meta_validate_events': >> kernel/trace/ring_buffer.c:1965:36: error: 'bpage' undeclared (first use in >> this function); did you mean 'page'? 1965 | local_set(&bpage->entries, 0); | ^~~~~ include/asm-generic/local.h:30:44: note: in definition of macro 'local_set' 30 | #define local_set(l,i) atomic_long_set((&(l)->a),(i)) | ^ kernel/trace/ring_buffer.c:1965:36: note: each undeclared identifier is reported only once for each function it appears in 1965 | local_set(&bpage->entries, 0); | ^~~~~ include/asm-generic/local.h:30:44: note: in definition of macro 'local_set' 30 | #define local_set(l,i) atomic_long_set((&(l)->a),(i)) | ^ vim +1965 kernel/trace/ring_buffer.c 1910 1911 /* If the meta data has been validated, now validate the events */ 1912 static void rb_meta_validate_events(struct ring_buffer_per_cpu *cpu_buffer) 1913 { 1914 struct ring_buffer_cpu_meta *meta = cpu_buffer->ring_meta; 1915 struct buffer_page *head_page, *orig_head; 1916 unsigned long entry_bytes = 0; 1917 unsigned long entries = 0; 1918 int discarded = 0; 1919 int ret; 1920 u64 ts; 1921 int i; 1922 1923 if (!meta || !meta->head_buffer) 1924 return; 1925 1926 orig_head = head_page = cpu_buffer->head_page; 1927 1928 /* Do the reader page first */ 1929 ret = rb_validate_buffer(cpu_buffer->reader_page, cpu_buffer->cpu, meta); 1930 if (ret < 0) { 1931 pr_info("Ring buffer meta [%d] invalid reader page detected\n", 1932 cpu_buffer->cpu); 1933 discarded++; 1934 } else { 1935 entries += ret; 1936 entry_bytes += rb_page_size(cpu_buffer->reader_page); 1937 } 1938 1939 ts = head_page->page->time_stamp; 1940 1941 /* 1942 * Try to rewind the head so that we can read the pages which already 1943 * read in the previous boot. 1944 */ 1945 if (head_page == cpu_buffer->tail_page) 1946 goto skip_rewind; 1947 1948 rb_dec_page(&head_page); 1949 for (i = 0; i < meta->nr_subbufs + 1; i++, rb_dec_page(&head_page)) { 1950 1951 /* Rewind until tail (writer) page. */ 1952 if (head_page == cpu_buffer->tail_page) 1953 break; 1954 1955 /* Rewind until unused page (no timestamp, no commit). */ 1956 if (!head_page->page->time_stamp && rb_page_commit(head_page) == 0) 1957 break; 1958 1959 /* 1960 * Skip if the page is invalid, or its timestamp is newer than the 1961 * previous valid page. 1962 */ 1963 ret = rb_validate_buffer(head_page, cpu_buffer->cpu, meta); 1964 if (ret >= 0 && ts < head_page->page->time_stamp) { > 1965 local_set(&bpage->entries, 0); 1966 local_set(&bpage->page->commit, 0); 1967 head_page->page->time_stamp = ts; 1968 ret = -1; 1969 } 1970 if (ret < 0) { 1971 if (!discarded) 1972 pr_info("Ring buffer meta [%d] invalid buffer page detected\n", 1973 cpu_buffer->cpu); 1974 discarded++; 1975 } else { 1976 entries += ret; 1977 entry_bytes += rb_page_size(head_page); 1978 if (ret > 0) 1979 local_inc(&cpu_buffer->pages_touched); 1980 ts = head_page->page->time_stamp; 1981 } 1982 } 1983 if (i) 1984 pr_info("Ring buffer [%d] rewound %d pages\n", cpu_buffer->cpu, i); 1985 1986 /* The last rewound page must be skipped. */ 1987 if (head_page != orig_head) 1988 rb_inc_page(&head_page); 1989 1990 /* 1991 * If the ring buffer was rewound, then inject the reader page 1992 * into the location just before the original head page. 1993 */ 1994 if (head_page != orig_head) { 1995 struct buffer_page *bpage = orig_head; 1996 1997 rb_dec_page(&bpage); 1998 /* 1999 * Insert the reader_page before the original head page. 2000 * Since the list encode RB_PAGE flags, general list 2001 * operations should be avoided. 2002 */ 2003 cpu_buffer->reader_page->list.next = &orig_head->list; 2004 cpu_buffer->reader_page->list.prev = orig_head->list.prev; 2005 orig_head->list.prev = &cpu_buffer->reader_page->list; 2006 bpage->list.next = &cpu_buffer->reader_page->list; 2007 2008 /* Make the head_page the reader page */ 2009 cpu_buffer->reader_page = head_page; 2010 bpage = head_page; 2011 rb_inc_page(&head_page); 2012 head_page->list.prev = bpage->list.prev; 2013 rb_dec_page(&bpage); 2014 bpage->list.next = &head_page->list; 2015 rb_set_list_to_head(&bpage->list); 2016 cpu_buffer->pages = &head_page->list; 2017 2018 cpu_buffer->head_page = head_page; 2019 meta->head_buffer = (unsigned long)head_page->page; 2020 2021 /* Reset all the indexes */ 2022 bpage = cpu_buffer->reader_page; 2023 meta->buffers[0] = rb_meta_subbuf_idx(meta, bpage->page); 2024 bpage->id = 0; 2025 2026 for (i = 1, bpage = head_page; i < meta->nr_subbufs; 2027 i++, rb_inc_page(&bpage)) { 2028 meta->buffers[i] = rb_meta_subbuf_idx(meta, bpage->page); 2029 bpage->id = i; 2030 } 2031 2032 /* We'll restart verifying from orig_head */ 2033 head_page = orig_head; 2034 } 2035 2036 skip_rewind: 2037 /* If the commit_buffer is the reader page, update the commit page */ 2038 if (meta->commit_buffer == (unsigned long)cpu_buffer->reader_page->page) { 2039 cpu_buffer->commit_page = cpu_buffer->reader_page; 2040 /* Nothing more to do, the only page is the reader page */ 2041 goto done; 2042 } 2043 2044 /* Iterate until finding the commit page */ 2045 for (i = 0; i < meta->nr_subbufs + 1; i++, rb_inc_page(&head_page)) { 2046 2047 /* Reader page has already been done */ 2048 if (head_page == cpu_buffer->reader_page) 2049 continue; 2050 2051 ret = rb_validate_buffer(head_page, cpu_buffer->cpu, meta); 2052 if (ret < 0) { 2053 if (!discarded) 2054 pr_info("Ring buffer meta [%d] invalid buffer page detected\n", 2055 cpu_buffer->cpu); 2056 discarded++; 2057 } else { 2058 /* If the buffer has content, update pages_touched */ 2059 if (ret) 2060 local_inc(&cpu_buffer->pages_touched); 2061 2062 entries += ret; 2063 entry_bytes += rb_page_size(head_page); 2064 } 2065 if (head_page == cpu_buffer->commit_page) 2066 break; 2067 } 2068 2069 if (head_page != cpu_buffer->commit_page) { 2070 pr_info("Ring buffer meta [%d] commit page not found\n", 2071 cpu_buffer->cpu); 2072 goto invalid; 2073 } 2074 done: 2075 local_set(&cpu_buffer->entries, entries); 2076 local_set(&cpu_buffer->entries_bytes, entry_bytes); 2077 2078 pr_info("Ring buffer meta [%d] is from previous boot! (%d pages discarded)\n", 2079 cpu_buffer->cpu, discarded); 2080 return; 2081 2082 invalid: 2083 /* The content of the buffers are invalid, reset the meta data */ 2084 meta->head_buffer = 0; 2085 meta->commit_buffer = 0; 2086 2087 /* Reset the reader page */ 2088 local_set(&cpu_buffer->reader_page->entries, 0); 2089 local_set(&cpu_buffer->reader_page->page->commit, 0); 2090 2091 /* Reset all the subbuffers */ 2092 for (i = 0; i < meta->nr_subbufs - 1; i++, rb_inc_page(&head_page)) { 2093 local_set(&head_page->entries, 0); 2094 rb_init_page(head_page->page); 2095 } 2096 } 2097 -- 0-DAY CI Kernel Test Service https://github.com/intel/lkp-tests/wiki
