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Tue, 19 May 2026 09:20:41 -0700 (PDT) Received: from milan ([2001:9b1:d5a0:a500::24b]) by smtp.gmail.com with ESMTPSA id 38308e7fff4ca-395882c7214sm22512551fa.14.2026.05.19.09.20.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 1EB2D8000B X-Stat-Signature: 4xx6ue8za8qaxrzr7977dyuufdb5t85s X-HE-Tag: 1779207642-638238 X-HE-Meta: U2FsdGVkX1/yIswEDyVA7bdp54QO9q1QrPLcygPymPzAZM3gfzw9asYC6kRYgwxcSD13h1PttAKByKGQlZ0186htixZohJ/1RHisYM7a7hLjhp4VcuLFTBw9xmuSaMGGyfBnuPcXBnGBlV2CfZOHNXsrAYqBT24LRWMZ4cpsRLeo6cz4fAB62CTyECz2A91/wq6rH2gndZB5mCYEXzQTpb5FdxAnIIvVbxI8LLdbs0Tx2Sy0hf3+c7jXuT8xYnwPqylrYDmvE2z/Uu2jW19Tv6GfxZ8giysEo/fQCfQICaA78bBBrqMSCkeNlQJQ3Qn60CwnVpJfE+Qh/G19x1BJWSbXrpP/cbZ9M9furcOgSLS2ks1MXdDw5TrmUVQ7lIEP/vSt49iV6b/oUpUJnoXBQKsQOIUaCYlkm4aH5xFh4+lTQev8aCHeBdvN7YfPdTrcjNx95gol2UboxCm2Mp3T737m5L42G0dPgzguAT/7v21u9n5zUgCdiO7UD1tGwomkeTbokViAlH84s5tJ8U8NYv1DNXzMiNJIQYCYLtXQh6tRTODNlwvsPEtqYi1148Esqjaxx3maEHgIgmn1m4giMyPagZ5h3hGAX+s4IUU1Q7C0LDkKN3YBRBsr+65QsKSoBlqFBu//g52wrJiU7MGDUNzIQjk/E/rPjNib8PwdssEYVwwO40hGCcWtgWjCD6yEQ3R9FcXIXt3BkA8r488xpELOzOCIADXGpp8yIhXdu92yWzQcNy87OR5bh6k4Y28Oej9F0bm5eNZ4TRzO+4bo/xz43zV9R38twZagunrRd9mVZwpN3PrJajxF6yImhaknZfaOQS4f8anDZkEwMJFzZDhRDwUKDwqS6kyyH/LPnmwtuuvCAZrhH2u9X4nS+43H0WfBIo8luYMChLO1/RVEtxqbtbFA5GFVGuMuuTRLHN43A6wlVjsjtjfHN42feTaBviXIxP83gd68W0d2/O+ 5YWv68L9 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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