Tetsuo 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> > --- > mm/kasan/generic.c | 4 ++-- > mm/kasan/tags.c | 2 +- > mm/kmsan/core.c | 6 +++--- > mm/kmsan/instrumentation.c | 2 +- > 4 files changed, 7 insertions(+), 7 deletions(-) > > diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c > index e5eef670735e..2c94f4943240 100644 > --- a/mm/kasan/generic.c > +++ b/mm/kasan/generic.c > @@ -488,7 +488,7 @@ static void __kasan_record_aux_stack(void *addr, bool can_alloc) > return; > > alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0]; > - alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT, can_alloc); > + alloc_meta->aux_stack[0] = kasan_save_stack(0, can_alloc); > } > > void kasan_record_aux_stack(void *addr) > @@ -518,7 +518,7 @@ void kasan_save_free_info(struct kmem_cache *cache, void *object) > if (!free_meta) > return; > > - kasan_set_track(&free_meta->free_track, GFP_NOWAIT); > + kasan_set_track(&free_meta->free_track, 0); > /* The object was freed and has free track set. */ > *(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREETRACK; > } > diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c > index 67a222586846..7dcfe341d48e 100644 > --- a/mm/kasan/tags.c > +++ b/mm/kasan/tags.c > @@ -140,5 +140,5 @@ void kasan_save_alloc_info(struct kmem_cache *cache, void *object, gfp_t flags) > > void kasan_save_free_info(struct kmem_cache *cache, void *object) > { > - save_stack_info(cache, object, GFP_NOWAIT, true); > + save_stack_info(cache, object, 0, true); > } > diff --git a/mm/kmsan/core.c b/mm/kmsan/core.c > index 7d1e4aa30bae..3adb4c1d3b19 100644 > --- a/mm/kmsan/core.c > +++ b/mm/kmsan/core.c > @@ -74,7 +74,7 @@ depot_stack_handle_t kmsan_save_stack_with_flags(gfp_t flags, > nr_entries = stack_trace_save(entries, KMSAN_STACK_DEPTH, 0); > > /* Don't sleep. */ > - flags &= ~__GFP_DIRECT_RECLAIM; > + flags &= ~(__GFP_DIRECT_RECLAIM | __GFP_KSWAPD_RECLAIM); > > handle = __stack_depot_save(entries, nr_entries, flags, true); > return stack_depot_set_extra_bits(handle, extra); > @@ -245,7 +245,7 @@ depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id) > extra_bits = kmsan_extra_bits(depth, uaf); > > entries[0] = KMSAN_CHAIN_MAGIC_ORIGIN; > - entries[1] = kmsan_save_stack_with_flags(GFP_ATOMIC, 0); > + entries[1] = kmsan_save_stack_with_flags(__GFP_HIGH, 0); > entries[2] = id; > /* > * @entries is a local var in non-instrumented code, so KMSAN does not > @@ -253,7 +253,7 @@ depot_stack_handle_t kmsan_internal_chain_origin(depot_stack_handle_t id) > * positives when __stack_depot_save() passes it to instrumented code. > */ > kmsan_internal_unpoison_memory(entries, sizeof(entries), false); > - handle = __stack_depot_save(entries, ARRAY_SIZE(entries), GFP_ATOMIC, > + handle = __stack_depot_save(entries, ARRAY_SIZE(entries), __GFP_HIGH, > true); > return stack_depot_set_extra_bits(handle, extra_bits); > } > diff --git a/mm/kmsan/instrumentation.c b/mm/kmsan/instrumentation.c > index cf12e9616b24..cc3907a9c33a 100644 > --- a/mm/kmsan/instrumentation.c > +++ b/mm/kmsan/instrumentation.c > @@ -282,7 +282,7 @@ void __msan_poison_alloca(void *address, uintptr_t size, char *descr) > > /* stack_depot_save() may allocate memory. */ > kmsan_enter_runtime(); > - handle = stack_depot_save(entries, ARRAY_SIZE(entries), GFP_ATOMIC); > + handle = stack_depot_save(entries, ARRAY_SIZE(entries), __GFP_HIGH); > kmsan_leave_runtime(); > > kmsan_internal_set_shadow_origin(address, size, -1, handle,
