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Tue, 19 May 2026 09:20:40 -0700 (PDT) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Tue, 19 May 2026 18:20:39 +0200 To: Baoquan He Cc: "Uladzislau Rezki (Sony)" , 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> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, May 19, 2026 at 09:40:19AM +0800, Baoquan He wrote: > 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 > Thank you! -- Uladzislau Rezki