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Fri, 06 Nov 2026 06:43:24 -0800 (PST) From: Uladzislau Rezki X-Google-Original-From: Uladzislau Rezki Date: Fri, 6 Nov 2026 15:43:21 +0100 To: Linus Torvalds Cc: Uladzislau Rezki , Herbert Xu , "Liam R. Howlett (Google)" , Davidlohr Bueso , Michal Hocko , Baoquan He , Alexander Potapenko , Andrey Ryabinin , Marco Elver , Michal Hocko , Linux Crypto Mailing List , Andrew Morton , Thomas Graf , linux-mm@kvack.org, linux-kernel@vger.kernel.org, maple-tree@lists.infradead.org, Lorenzo Stoakes , Chris Mason , Alice Ryhl , Andrew Ballance , stable@vger.kernel.org, "David Hildenbrand (Arm)" Subject: Re: [PATCH 4/4] rhashtable: fix vmalloc() deadlock in atomic rehash Message-ID: References: X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: 1jcxh3z845xfmnuni94f5gindw11d8yp X-Rspamd-Queue-Id: 0102F40003 X-Rspam-User: X-Rspamd-Server: rspam08 X-Spam-Status: No, score=-7.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793976207-134148 X-HE-Meta: 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 iBxi7pMY 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 05, 2026 at 01:02:35PM -0800, Linus Torvalds wrote: > On Thu, 5 Nov 2026 at 10:44, Uladzislau Rezki wrote: > > > > @@ -1025,7 +1025,13 @@ void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source, > > } > > } > > } else { > > - spin_lock(&br->hash_lock); > > + if (in_serving_softirq()) { > > + if (!spin_trylock(&br->hash_lock)) > > I don't think that in_serving_softirq() makes any sense. > > If I read this code correctly - and it's possible I didn't - this is > always called under local_bh_disable(). > > And local_bh_disable() will have increased the preempt-count exactly > so that it looks like it's in_serving_softirq(). > Sorry, probably i am missing something here. My understanding is that local_bh_disable() adds SOFTIRQ_DISABLE_OFFSET and in_serving_softirq() checks another SOFTIRQ_OFFSET bit. -- Uladzislau Rezki