On Wed, 31 May 2023 15:31:53 +0200 Alexander Potapenko <glider@xxxxxxxxxx> wrote: > On Mon, May 29, 2023 at 3:08 AM Huang, Ying <ying.huang@xxxxxxxxx> wrote: > > > > ? Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> writes: > > > > > syzbot is reporting lockdep warning in __stack_depot_save(), for > > > the caller of __stack_depot_save() (i.e. __kasan_record_aux_stack() in > > > this report) is responsible for masking __GFP_KSWAPD_RECLAIM flag in > > > order not to wake kswapd which in turn wakes kcompactd. > > > > > > Since kasan/kmsan functions might be called with arbitrary locks held, > > > mask __GFP_KSWAPD_RECLAIM flag from all GFP_NOWAIT/GFP_ATOMIC allocations > > > in kasan/kmsan. > > > > > > Note that kmsan_save_stack_with_flags() is changed to mask both > > > __GFP_DIRECT_RECLAIM flag and __GFP_KSWAPD_RECLAIM flag, for > > > wakeup_kswapd() from wake_all_kswapds() from __alloc_pages_slowpath() > > > calls wakeup_kcompactd() if __GFP_KSWAPD_RECLAIM flag is set and > > > __GFP_DIRECT_RECLAIM flag is not set. > > > > > > Reported-by: syzbot <syzbot+ece2915262061d6e0ac1@xxxxxxxxxxxxxxxxxxxxxxxxx> > > > Closes: https://syzkaller.appspot.com/bug?extid=ece2915262061d6e0ac1 > > > Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> > > > > This looks good to me. Thanks! > > > > Reviewed-by: "Huang, Ying" <ying.huang@xxxxxxxxx> > > Sorry for the late reply, but maybe it would be better to mask this > flag in __stack_depot_save() (lib/stackdepot.c) instead? > We are already masking out a number of flags there, and the problem > seems quite generic. Tetsuo?
