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From: Baoquan He To: "Uladzislau Rezki (Sony)" Cc: linux-mm@kvack.org, Andrew Morton , Baoquan He , LKML , Ido Schimmel , syzbot+8b12fc6e0fb139765b58@syzkaller.appspotmail.com Subject: Re: [PATCH] mm/vmalloc: Do not trigger BUG() on BH disabled context Message-ID: References: <20260515153009.2296191-1-urezki@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260515153009.2296191-1-urezki@gmail.com> X-Migadu-Flow: FLOW_OUT X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 6B953120009 X-Stat-Signature: nhxsh75zn4qn1tnot9p941e5cp3o59uu X-HE-Tag: 1779154829-356645 X-HE-Meta: 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 9gMuZAZL NtEb/3ABhVlDRO6a5jJFg0Gsx8u9B2aUVXUbUeLjdoh8f31SlEYo9YQFcjvMRxySNPIMpwtqQGFRbRkXAuLNBIci1E019DeJTm/mvQsutR2QfEwRvAr7fdP8Jo31zjfmARYfnz73stsY4FWvOD/bN+3yqt5gpsKwhL3K+Nz81HT/tSSa6696xz3rs34RoIaWY5qun/xOWImvIgt+aAPmWBXghSbDf1ju4ez+8WlKzFqvQu/7y3t8QESQhd0fwkwWSG1xQi9mUDQ+dwsElxZoKYjXLWSdQKXO5UQX8EVmYkvX2SzPEGPsuYcnbqUjpIzEoSqdiALejZwx5ZHTU20o6qmOyxH0ZR1CqwlZQxWMNEPSZs45B9HC0WbZeKCknq/Wm/v8RT0ayiWfZ42Oalrx84SFMtWJv4CyKYeTyO6GRm4hfAoQeW6T+CEpVIUeA80ieNjdn4iGm7+iyTM29p5AR2+hB2E2InpX4tcEPe5c7/tRJ07A= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/15/26 at 05:30pm, Uladzislau Rezki (Sony) wrote: > __get_vm_area_node() currently triggers a BUG() if in_interrupt() > returns true. However, in_interrupt() also reports true when BH > are disabled. > > The bridge code can call rhashtable_lookup_insert_fast() with > bottom halves disabled: > > __vlan_add() > -> br_fdb_add_local() > spin_lock_bh(&br->hash_lock); <-- Disable BH > -> fdb_add_local() > -> fdb_create() > -> rhashtable_lookup_insert_fast() > -> kvmalloc() > -> vmalloc() > -> __get_vm_area_node() > -> BUG_ON(in_interrupt()) > spin_unlock_bh(&br->hash_lock) > > this triggers the BUG() despite the caller not being in NMI or > hard IRQ context. Because the current vmalloc supports non-blocking allocation, so we need to skip disabled BH or in_serving_softirq() cases to avoid unwanted BUG(). This change looks great to me, not sure if I undersand it correctly. Reviewed-by: Baoquan He Thanks Baoquan > > Replace the in_interrupt() check with in_nmi() || in_hardirq(). > > Cc: Ido Schimmel > Fixes: c6307674ed82 ("mm: kvmalloc: add non-blocking support for vmalloc") > Reported-by: syzbot+8b12fc6e0fb139765b58@syzkaller.appspotmail.com > Closes: https://lore.kernel.org/all/69ff8c7c.050a0220.1036b8.000b.GAE@google.com/ > Signed-off-by: Uladzislau Rezki (Sony) > --- > mm/vmalloc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index 676851d5cfe7..273bbe49eaef 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -3209,7 +3209,7 @@ struct vm_struct *__get_vm_area_node(unsigned long size, > struct vm_struct *area; > unsigned long requested_size = size; > > - BUG_ON(in_interrupt()); > + BUG_ON(in_nmi() || in_hardirq()); > size = ALIGN(size, 1ul << shift); > if (unlikely(!size)) > return NULL; > -- > 2.47.3 >