From: Tetsuo Handa penguin-kernel@I-love.SAKURA.ne.jp
commit eb799279fb1f9c63c520fe8c1c41cb9154252db6 upstream.
syzbot is reporting a lockdep warning in fill_pool() because the allocation from debugobjects is using GFP_ATOMIC, which is (__GFP_HIGH | __GFP_KSWAPD_RECLAIM) and therefore tries to wake up kswapd, which acquires kswapd_wait::lock.
Since fill_pool() might be called with arbitrary locks held, fill_pool() should not assume that acquiring kswapd_wait::lock is safe.
Use __GFP_HIGH instead and remove __GFP_NORETRY as it is pointless for !__GFP_DIRECT_RECLAIM allocation.
Fixes: 3ac7fe5a4aab ("infrastructure to debug (dynamic) objects") Reported-by: syzbot syzbot+fe0c72f0ccbb93786380@syzkaller.appspotmail.com 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/6577e1fa-b6ee-f2be-2414-a2b51b1c5e30@I-love.SAKURA... Closes: https://syzkaller.appspot.com/bug?extid=fe0c72f0ccbb93786380 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- lib/debugobjects.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/lib/debugobjects.c +++ b/lib/debugobjects.c @@ -128,7 +128,7 @@ static const char *obj_states[ODEBUG_STA
static void fill_pool(void) { - gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN; + gfp_t gfp = __GFP_HIGH | __GFP_NOWARN; struct debug_obj *obj; unsigned long flags;