From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit 8b64d420fe2450f82848178506d3e3a0bd195539 upstream.
syzbot is reporting false a positive ODEBUG message immediately after ODEBUG was disabled due to OOM.
[ 1062.309646][T22911] ODEBUG: Out of memory. ODEBUG disabled [ 1062.886755][ T5171] ------------[ cut here ]------------ [ 1062.892770][ T5171] ODEBUG: assert_init not available (active state 0) object: ffffc900056afb20 object type: timer_list hint: process_timeout+0x0/0x40
CPU 0 [ T5171] CPU 1 [T22911] -------------- -------------- debug_object_assert_init() { if (!debug_objects_enabled) return; db = get_bucket(addr); lookup_object_or_alloc() { debug_objects_enabled = 0; return NULL; } debug_objects_oom() { pr_warn("Out of memory. ODEBUG disabled\n"); // all buckets get emptied here, and } lookup_object_or_alloc(addr, db, descr, false, true) { // this bucket is already empty. return ERR_PTR(-ENOENT); } // Emits false positive warning. debug_print_object(&o, "assert_init"); }
Recheck debug_object_enabled in debug_print_object() to avoid that.
Reported-by: syzbot syzbot+7937ba6a50bdd00fffdf@syzkaller.appspotmail.com Suggested-by: Thomas Gleixner tglx@linutronix.de Signed-off-by: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp Signed-off-by: Thomas Gleixner tglx@linutronix.de Link: https://lore.kernel.org/r/492fe2ae-5141-d548-ebd5-62f5fe2e57f7@I-love.SAKURA... Closes: https://syzkaller.appspot.com/bug?extid=7937ba6a50bdd00fffdf Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- lib/debugobjects.c | 9 +++++++++ 1 file changed, 9 insertions(+)
--- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -498,6 +498,15 @@ static void debug_print_object(struct de const struct debug_obj_descr *descr = obj->descr; static int limit;
+ /* + * Don't report if lookup_object_or_alloc() by the current thread + * failed because lookup_object_or_alloc()/debug_objects_oom() by a + * concurrent thread turned off debug_objects_enabled and cleared + * the hash buckets. + */ + if (!debug_objects_enabled) + return; + if (limit < 5 && descr != descr_test) { void *hint = descr->debug_hint ? descr->debug_hint(obj->object) : NULL;