From: Thomas Richter tmricht@linux.ibm.com
[ Upstream commit 8a07aa4e9b7b0222129c07afff81634a884b2866 ]
Debugging a OOM error using the TUI interface revealed this issue on s390:
[tmricht@m83lp54 perf]$ cat /proc/kallsyms |sort .... 00000001119b7158 B radix_tree_node_cachep 00000001119b8000 B __bss_stop 00000001119b8000 B _end 000003ff80002850 t autofs_mount [autofs4] 000003ff80002868 t autofs_show_options [autofs4] 000003ff80002a98 t autofs_evict_inode [autofs4] ....
There is a huge gap between the last kernel symbol __bss_stop/_end and the first kernel module symbol autofs_mount (from autofs4 module).
After reading the kernel symbol table via functions:
dso__load() +--> dso__load_kernel_sym() +--> dso__load_kallsyms() +--> __dso_load_kallsyms() +--> symbols__fixup_end()
the symbol __bss_stop has a start address of 1119b8000 and an end address of 3ff80002850, as can be seen by this debug statement:
symbols__fixup_end __bss_stop start:0x1119b8000 end:0x3ff80002850
The size of symbol __bss_stop is 0x3fe6e64a850 bytes! It is the last kernel symbol and fills up the space until the first kernel module symbol.
This size kills the TUI interface when executing the following code:
process_sample_event() hist_entry_iter__add() hist_iter__report_callback() hist_entry__inc_addr_samples() symbol__inc_addr_samples(symbol = __bss_stop) symbol__cycles_hist() annotated_source__alloc_histograms(..., symbol__size(sym), ...)
This function allocates memory to save sample histograms. The symbol_size() marco is defined as sym->end - sym->start, which results in above value of 0x3fe6e64a850 bytes and the call to calloc() in annotated_source__alloc_histograms() fails.
The histgram memory allocation might fail, make this failure no-fatal and continue processing.
Output before: [tmricht@m83lp54 perf]$ ./perf --debug stderr=1 report -vvvvv \ -i ~/slow.data 2>/tmp/2 [tmricht@m83lp54 perf]$ tail -5 /tmp/2 __symbol__inc_addr_samples(875): ENOMEM! sym->name=__bss_stop, start=0x1119b8000, addr=0x2aa0005eb08, end=0x3ff80002850, func: 0 problem adding hist entry, skipping event 0x938b8 [0x8]: failed to process type: 68 [Cannot allocate memory] [tmricht@m83lp54 perf]$
Output after: [tmricht@m83lp54 perf]$ ./perf --debug stderr=1 report -vvvvv \ -i ~/slow.data 2>/tmp/2 [tmricht@m83lp54 perf]$ tail -5 /tmp/2 symbol__inc_addr_samples map:0x1597830 start:0x110730000 end:0x3ff80002850 symbol__hists notes->src:0x2aa2a70 nr_hists:1 symbol__inc_addr_samples sym:unlink_anon_vmas src:0x2aa2a70 __symbol__inc_addr_samples: addr=0x11094c69e 0x11094c670 unlink_anon_vmas: period++ [addr: 0x11094c69e, 0x2e, evidx=0] => nr_samples: 1, period: 526008 [tmricht@m83lp54 perf]$
There is no error about failed memory allocation and the TUI interface shows all entries.
Signed-off-by: Thomas Richter tmricht@linux.ibm.com Reviewed-by: Hendrik Brueckner brueckner@linux.ibm.com Cc: Heiko Carstens heiko.carstens@de.ibm.com Cc: Hendrik Brueckner brueckner@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/90cb5607-3e12-5167-682d-978eba7dafa8@linux.ibm.com Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/annotate.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-)
diff --git a/tools/perf/util/annotate.c b/tools/perf/util/annotate.c index dfee110b3a58..c357051dd2b6 100644 --- a/tools/perf/util/annotate.c +++ b/tools/perf/util/annotate.c @@ -911,9 +911,8 @@ static int symbol__inc_addr_samples(struct symbol *sym, struct map *map, if (sym == NULL) return 0; src = symbol__hists(sym, evsel->evlist->nr_entries); - if (src == NULL) - return -ENOMEM; - return __symbol__inc_addr_samples(sym, map, src, evsel->idx, addr, sample); + return (src) ? __symbol__inc_addr_samples(sym, map, src, evsel->idx, + addr, sample) : 0; }
static int symbol__account_cycles(u64 addr, u64 start,