On Thu, 11 May 2023 22:47:32 +0900 Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> wrote: > syzbot is reporting lockdep warning in fill_pool(), for GFP_ATOMIC is > (__GFP_HIGH | __GFP_KSWAPD_RECLAIM) which wakes up kswapd. > Since fill_pool() might be called with arbitrary locks held, > fill_pool() should not assume that holding pgdat->kswapd_wait is safe. hm. But many GFP_ATOMIC allocation attempts are made with locks held. Why aren't all such callers buggy, by trying to wake kswapd with locks held? What's special about this one? > Also, __GFP_NORETRY is pointless for !__GFP_DIRECT_RECLAIM allocation > > Reported-by: syzbot <syzbot+fe0c72f0ccbb93786380@xxxxxxxxxxxxxxxxxxxxxxxxx> > Closes: https://syzkaller.appspot.com/bug?extid=fe0c72f0ccbb93786380 > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > Fixes: 3ac7fe5a4aab ("infrastructure to debug (dynamic) objects") > --- > lib/debugobjects.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/lib/debugobjects.c b/lib/debugobjects.c > index 003edc5ebd67..986adca357b4 100644 > --- a/lib/debugobjects.c > +++ b/lib/debugobjects.c > @@ -126,7 +126,7 @@ static const char *obj_states[ODEBUG_STATE_MAX] = { > > static void fill_pool(void) > { > - gfp_t gfp = GFP_ATOMIC | __GFP_NORETRY | __GFP_NOWARN; > + gfp_t gfp = __GFP_HIGH | __GFP_NOWARN; Does this weaken fill_pool()'s allocation attempt more than necessary? We can still pass __GFP_HIGH?
