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> --- 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, -- 2.34.1
