The patch titled
Subject: debugobjects: turn off debug_objects_enabled from debug_objects_oom()
has been added to the -mm mm-nonmm-unstable branch. Its filename is
debugobjects-turn-off-debug_objects_enabled-from-debug_objects_oom.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/debugobjects-turn-off-debug_objects_enabled-from-debug_objects_oom.patch
This patch will later appear in the mm-nonmm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/process/submit-checklist.rst when testing your code ***
The -mm tree is included into linux-next via the mm-everything
branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
and is updated there every 2-3 working days
------------------------------------------------------
From: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Subject: debugobjects: turn off debug_objects_enabled from debug_objects_oom()
Date: Mon, 29 May 2023 23:39:12 +0900
syzbot is reporting false 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
This race happened because debug_objects_oom() emitted OOM message but did
not turn off debug_objects_enabled, and debug_print_object() did not check
debug_objects_enabled when calling WARN().
CPU 0 [ T5171] CPU 1 [T22911]
-------------- --------------
debug_object_assert_init() {
if (!debug_objects_enabled)
return;
db = get_bucket((unsigned long) addr); // Finds a bucket, but...
debug_objects_oom() {
pr_warn("Out of memory. ODEBUG disabled
");
// all buckets get emptied here, and...
hlist_move_list(&db->list, &freelist);
}
lookup_object_or_alloc(addr, db, descr, false, true) {
lookup_object(addr, b) {
return NULL; // this bucket is already empty.
}
if (!descr->is_static_object || !descr->is_static_object(addr))
return ERR_PTR(-ENOENT);
}
if (!obj) { // obj == ERR_PTR(-ENOENT) because non-static object.
debug_objects_oom();
return;
}
debug_print_object(&o, "assert_init") {
// False positive due to not checking debug_objects_enabled.
WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
"object: %p object type: %s hint: %pS
", ...);
}
}
Link: https://lkml.kernel.org/r/1af29817-4698-c5ac-cf63-0dad289e740f@xxxxxxxxxxxxxxxxxxx
Reported-by: syzbot <syzbot+7937ba6a50bdd00fffdf@xxxxxxxxxxxxxxxxxxxxxxxxx>
Closes: https://syzkaller.appspot.com/bug?extid=7937ba6a50bdd00fffdf
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Stephen Boyd <swboyd@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: wuchi <wuchi.zero@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
lib/debugobjects.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/lib/debugobjects.c~debugobjects-turn-off-debug_objects_enabled-from-debug_objects_oom
+++ a/lib/debugobjects.c
@@ -466,6 +466,7 @@ static void debug_objects_oom(void)
unsigned long flags;
int i;
+ debug_objects_enabled = 0;
pr_warn("Out of memory. ODEBUG disabled\n");
for (i = 0; i < ODEBUG_HASH_SIZE; i++, db++) {
@@ -502,10 +503,10 @@ static void debug_print_object(struct de
void *hint = descr->debug_hint ?
descr->debug_hint(obj->object) : NULL;
limit++;
- WARN(1, KERN_ERR "ODEBUG: %s %s (active state %u) "
- "object: %p object type: %s hint: %pS\n",
- msg, obj_states[obj->state], obj->astate,
- obj->object, descr->name, hint);
+ WARN(debug_objects_enabled, KERN_ERR
+ "ODEBUG: %s %s (active state %u) object: %p object type: %s hint: %pS\n",
+ msg, obj_states[obj->state], obj->astate,
+ obj->object, descr->name, hint);
}
debug_objects_warnings++;
}
_
Patches currently in -mm which might be from penguin-kernel@xxxxxxxxxxxxxxxxxxx are
workingset-refactor-lru-refault-to-expose-refault-recency-check-fix.patch
mm-page_alloc-dont-wake-up-kswapd-from-rmqueue-unless-__gfp_kswapd_reclaim-is-specified.patch
debugobjects-turn-off-debug_objects_enabled-from-debug_objects_oom.patch
